SR Safety Training Engineer at AVO Training Institute

Most of us have grown up with an understanding that high short circuits currents are detrimental. We have gone to a lot of efforts to reduce the level of short circuit currents wherever possible. We have invented current limiting fuses and other current limiting devices. We have intentionally placed impedance in the circuit to limit the amount of current available. The focus has been primarily on equipment preservation and continuous operation. For most of our lifetimes when you asked a utility to give you the short circuit availability they would give you the value considering only the impedance of the transformer. After all, it is worst case (highest current). It will be higher than including the impedance of the entire system (infinite bus).

That philosophy has served us well for the stated objectives. Personnel safety, however, requires a fresh look at this philosophy. When an arc flash event occurs workers are subjected to multiple hazards, one of which is burns. The calculated energy that produces the burn is known as incident energy and is expressed in calories/cm2 or joules/cm 2. The severity of burning as with all burns is a product of the heat generated and the exposure time to the heat. The duration of the heat energy in an electrical system is determined by the speed of the protective device that clears the short circuit or by other factors in the event of a device failure. Electrical protective devices operate on an inverse time-current relationship. See figure 1. Simply stated the device operates faster at higher current and slower at lower current.

Figure 1 is representative of a relay operating curve. The red lines indicate an operating time of 0.1 seconds at a current of 30,000 amperes and the green lines indicate an operating time of 1 second at 9,000 amperes. This inverse relationship is the same whether it is a fuse, a breaker, or a relay.

The time to clear the fault is further complicated because the current is passing through the air which has a higher resistance than the conductors and results in a lower current magnitude and a corresponding increase in clearing time of the protective device. Whether the longer exposure period has a higher impact than a higher current depends on the characteristics of the system. In my experience, most of the time, the longer clearing time is more critical than the higher short circuit current.

Consider the following case study:

A manufacturing facility was served by a transformer with an impedance of 1.5% which had standard over-current protection. The owner and the consulting engineer determined to replace the transformer with a 5.75% impedance transformer, with under-oil current limiting fuses in the primary of the transformer and cable limiters on the secondary cables. The resultant arcing current was below the current-limiting range of the limiting devices when buses were faulted downstream. The downstream incident energy rose from 5.9 cal/cm2 to 43.33 cal/cm2 (IEEE 1584 calculation). The situation changed from being very manageable with PPE protection to one which requires some further mitigation to reduce arc flash energy.

In conclusion, as we analyze and design electrical distribution systems it is necessary to study the harmful effects of both maximum short circuit currents (bolted faults) and lower impedance arcing short circuit currents.

Thermography and Infrared Light

Infrared light or thermography is the use of an infrared imaging and measurement camera to “see” and “measure” thermal energy emitted from an object. Thermal, or infrared energy, is light that is not visible because its wavelength is too long to be detected by the human eye; it’s the part of the electromagnetic spectrum that we perceive as heat. Unlike visible light, in the infrared world, everything with a temperature above absolute zero emits heat. Even very cold objects, like ice cubes, emit infrared.

Infrared Imaging

The higher the object’s temperature, the greater the IR radiation emitted. Infrared allows use to see what our eyes cannot. Infrared thermography cameras produce images of invisible infrared or “heat” radiation and provide precise non-contact temperature measurement capabilities. Nearly everything gets hot before it fails, making infrared cameras extremely cost-effective, valuable diagnostic tools in many diverse applications. And as industry strives to improve manufacturing efficiencies, manage energy, improve product quality, and enhance worker safety, new applications for infrared cameras continually emerge.

HOW DOES AN IR CAMERA WORK?

Infrared Energy Detection

An infrared camera is a non-contact device that detects infrared energy (heat) and converts it into an electronic signal, which is then processed to produce a thermal image on a video monitor and perform temperature calculations. Heat sensed by an infrared camera can be very precisely quantified, or measured, allowing you to not only monitor thermal performance, but also identify and evaluate the relative severity of heat-related problems.

Recent Infrared Innovations

Recent innovations, particularly detector technology, the incorporation of built-in visual imaging, automatic functionality, and infrared software development, deliver more cost-effective thermal analysis solutions than ever before.

WHY MEASURE TEMPERATURE?

Infrared and Temperature Measurement

Finding a problem with an infrared camera is sometimes not enough. In fact, an infrared camera image alone without accurate temperature measurements says very little about the condition of an electrical connection or worn mechanical part. Many electrical targets are operating properly at temperatures that are significantly above ambient. An infrared image without measurement can be misleading because it may visually suggest a problem that does not exist.

Predictive Maintenance

Infrared cameras that incorporate temperature measurement allow predictive maintenance professionals to make well informed judgements about the operating condition of electrical and mechanical targets. Temperature measurements can be compared with historical operating temperatures, or with infrared readings of similar equipment at the same time, to determine if a significant temperature rise will comprise component reliability or plant safety.

Digital Image Storage

Digital image storage, available on most FLIR infrared cameras, produces calibrated thermal images that contain over 78,000 independent temperature measurements that can be measured at any time.

WHY USE INFRARED?

A picture says a thousand words; infrared technology is the only diagnostic technology that lets you instantly visualize and verify thermal performance. FLIR’s infrared cameras show you thermal problems, quantify them with precise non-contact temperature measurement, and document them automatically in seconds with professional easy-to-create IR reports.

Infrared for Predictive Maintenance

Nearly everything that uses or transmits power gets hot before it fails. Cost effective power management is critical to maintaining the reliability of your electrical and mechanical systems. And today, no one would argue that infrared thermography is one of the most effective proven predictive maintenance (PM) technology available to quickly, accurately and safely locate problems prior to failure. Finding and fixing a poor electrical connection before a component fails can save you the much greater costs associated with manufacturing downtime, production losses, power outages, fires and catastrophic failures.

Infrared Cameras and Software that Work Together

But using infrared images to find a problem is sometimes not enough. In fact, an infrared camera image without an accurate measurement says very little  about the condition of an electrical connection or worn mechanical part. And, an IR survey without a simple, fast way to report and analyze inspection results provides no ability to make timely repair decision or locate and separate those ‘hot spots’ that can cause problems from those associated with equipment operating normally.

FLIR’s infrared cameras and software not only quickly locate problems, their non-contact precision temperature measurement and analysis capabilities instantly deliver the answers you need to understand what repair action to take, and when.

An Infrared Camera Just for You

Whether you’re looking at buildings or hybrid circuits, there’s a FLIR infrared camera right for your application. With a complete line of infrared cameras, software, accessories, world-class thermographic training and application support, FLIR stands ready to meet your specific infrared needs. FLIR is the one IR company you can specify and justify with confidence. Make sure that all the reliability you planned for gets delivered to your customer.

Global Test Supply is a distributor of FLIR Thermal Imaging Cameras. We have cameras for sell or rent. Give us a call today to talk to a sales technician about your thermal imaging needs.

The issues that determine what method is best for a given coating measurement include the type of coating, the substrate material, the thickness range of the coating, the size and shape of the part, and the cost of the equipment. Commonly used measuring techniques for cured organic films include nondestructive dry film methods such as magnetic, eddy current, ultrasonic, or micrometer measurement and also destructive dry film methods such as cross-sectioning or gravimetric (mass) measurement. Methods are also available for powder and liquid coatings to measure the film before it is cured.

Magnetic Film Thickness Gauges

Magnetic film gauges are used to non destructively measure the thickness of a nonmagnetic coating on ferrous substrates. Most coatings on steel and iron are measured this way. Magnetic gauges use one of two principles of operation: magnetic pull-off or magnetic/electromagnetic induction.

Magnetic Pull-off

Magnetic pull-off gauges use a permanent magnet, a calibrated spring, and a graduated scale. The attraction between the magnet and magnetic steel pulls the two together. As the coating thickness separating the two increases, it becomes easier to pull the magnet away. Coating thickness is determined by measuring this pull-off force. Thinner coatings  will have stronger magnetic attraction while thicker films will have comparatively less magnetic attraction. Testing with magnetic gauges is sensitive to surface roughness, curvature, substrate thickness, and the make up of the metal alloy.

Magnetic pull-off gages are rugged, simple, inexpensive, portable, and usually do not require any calibration adjustment. They are a good, low-cost alternative in situations where quality goals require only a few readings during production.

Pull-off gauges are typically pencil-type or rollback dial models. Pencil-type models (PosiPen shown in Fig 1) use a magnet that is mounted to a helical spring that works perpendicularly to the coated surface. Most pencil-type pull-off gauges have large magnets and are designed to work in only one or two positions, which partially compensate for gravity. A more accurate version is available, which has a tiny, precise magnet to measure on small, hot, or hard-to-reach surfaces. A triple indicator ensures accurate measurements when the gauge is pointed down, up, or horizontally with a tolerance of ±10%.

Fig 1 – Pencil-type magnetic pull-off thickness gauge

Rollback dial models (PosiTest shown in Fig 2) are the most common form of magnetic pull-off gauge. A magnet is attached to one end of a pivoting balanced arm and connected to a calibrated hairspring. By rotating the dial with a finger, the spring increases the force on the magnet an pulls it from the surface. These gauges are easy to use and have  balanced arm that allows them to work in any position, independent of gravity. They are safe in explosive environments and are commonly used by painting contractors and small powder coating operations. Typical tolerance is ±5%.

Fig 2 – Roll-back dial magnetic pull-off thickness gauge

Magnetic and Electromagnetic Induction

Magnetic induction instruments use a permanent magnet as the source of the magnetic field. A Hall-effect generator or magneto-resistor is used to sense the magnetic flux density at a pole of the magnet. Electromagnetic induction instruments use an alternating magnetic field. A soft, ferromagnetic rod wound with a coil of fine wire is used to produce a magnetic field. A second coil of wire is used to detect changes in magnetic flux.

These electronic instruments measure the change in magnetic flux density at the surface of a magnetic probe as it nears a steel surface. The magnitude of the flux density at the probe surface is directly related to the distance from the steel substrate. By measuring flux density the coating thickness can be determined.

Fig 3 – Electronic magnetic induction thickness gauges

Electronic magnetic gauges (e.g. PosiTector 6000 F Series, PosiTest DFT Ferrous) come in many shapes and sizes. They commonly use a constant pressure probe to provide consistent readings that are not influenced by different operators. Readings are shown on a liquid crystal display (LCD). They can have options to store measurement results, perform instant analysis of readings, and output results to a printer or computer for further examination. Typical tolerance is ±1%.

The manufacturer’s instructions should be carefully followed for most accurate results. Standard test methods are available in ASTM D 1186, D 7091-05, ISO 2178 and ISO 2808.

Eddy Current

Eddy current techniques are used to non destructively measure the thickness of non conductive coatings on nonferrous metal substrates. A coil of fine wire conducting a high-frequency alternating current (above 1 MHz) is used to set up an alternating magnetic field at the surface of the instrument’s probe. When the probe is brought near a conductive surface, the alternating magnetic field will set up eddy currents on the surface. The substrate characteristics and the distance of the probe from the substrate (the coating thickness) affect the magnitude of the eddy currents. The eddy currents create their own opposing electromagnetic field that can be sensed by the exciting coil or by a second, adjacent coil.

Eddy current coating thickness gauges (e.g. PosiTector 6000 N Series) look and operate like electronic magnetic gauges. They are used to measure coating thickness over all nonferrous metals. Like magnetic electronic gauges, they commonly use a constant pressure probe and display results on an LCD. They can also have options to store measurement results or perform instant analysis of readings and output to a printer or computer for further examination. The typical tolerance is ±1%. Testing is sensitive to surface roughness, curvature, substrate thickness, type of metal substrate and distance from an edge.

Standard methods for the application and performance of this test are available in ASTM B 244, ASTM D 1400, D 7091-05 and ISO 2360.

It is now common for gauges to incorporate both magnetic and eddy current principles into one unit (e.g. PosiTector 6000 FN, PosiTest DFT Combo). Some simplify the task of measuring most coatings over any metal by switching automatically from one principle of operation to the other, depending upon the substrate. These combination units are popular with painters and powder coaters.

Ultrasonic

The ultrasonic pulse-echo technique of ultrasonic gauges (e.g. PosiTector 200) is used to measure the thickness of coatings on nonmetal substrates (plastic, wood, etc.) without damaging the coating.

Fig 4 – Ultrasonic gauge can measure the thickness of coatings on nonmetallic substrates

The probe of the instrument contains an ultrasonic transducer that sends a pulse through the coating. The pulse reflects back from the substrate to the transducer and is converted into a high frequency electrical signal. The echo waveform is digitized and analyzed to determine coating thickness. In some circumstances, individual layers in a multi-layer system can be measured.

Typical tolerance for this device is ±3%. Standard methods for the application and performance of this test are available in ASTM D 6132.

Micrometer

Micrometers are sometimes used to check coating thickness. They have the advantage of measuring any coating/substrate combination but the disadvantage of requiring access to the bare substrate. The requirement to touch both the surface of the coating and the underside of the substrate can be limiting and they are often not sensitive enough to measure thin coatings.

Two measurements must be taken: one with the coating in place and the other without. The difference between the two readings, the height variation, is taken to be the coating thickness. On rough surfaces, micrometers measure coating thickness above the highest peak.

Destructive Tests

One destructive technique is to cut the coated part in a cross section and measure the film thickness by viewing the cut microscopically. Another cross sectioning technique uses a scaled microscope to view a geometric incision through the dry-film coating. A special cutting tool is used to make a small, precise V-groove through the coating and into the substrate. Gauges are available that come complete with cutting tips and illuminated scaled magnifier.

While the principles of this destructive method are easy to understand, there are opportunities for measuring error. It takes skill to prepare the sample and interpret the results. Adjusting the measurement reticule to a jagged or indistinct interface may create inaccuracy, particularly between different operators. This method is used when inexpensive, nondestructive methods are not possible, or as a way of confirming nondestructive results. ASTM D 4138 outlines a standard method for this measurement system.

Gravimetric

By measuring the mass and area of the coating, thickness can be determined. The simplest method is to weigh the part before and after coating. Once the mass and area have been determined, the thickness is calculated using the following equation:

T = m x 10
A x d

where T is the thickness in micrometers, m is the mass of the coating in milligrams, A is the area tested in square centimeters, and d is the density in grams per cubic centimeter.

It is difficult to relate the mass of the coating to thickness when the substrate is rough or the coating uneven. Laboratories are best equipped to handle this time-consuming and often destructive method.

Measurement Before Cure

Wet-film thickness gauges help determine how much material to apply wet to achieve a specified dry-film thickness provided that the percent of solids by volume is known. They measure all types of wet organic coatings, such as paint, varnish, and lacquer on flat or curved smooth surfaces.

Measuring wet film thickness during application identifies the need for immediate correction and adjustment by the applicator. Correction of the film after it has dried or chemically cured requires costly extra labor time, may lead to contamination of the film, and may introduce problems of adhesion and integrity of the coating system.

The equations for determining the correct wet-film thickness (WFT), both with and without thinner, are as follows:

Without thinner:

WFT = desired dry film thickness
% of solids by volume

With thinner:

WFT = desired dry film thickness  /  % of solids by volume
100%   +   % of thinner added

Wet-film is most often measured with a wet film comb or wheel. The wet-film comb is a flat aluminum, plastic, or stainless steel plate with calibrated notches on the edge of each face. The gauge is placed squarely and firmly onto the surface to be measured immediately after coating application and then removed. The wet-film thickness lies between the highest coated notch and the next uncoated notch. Notched gauge measurements are neither accurate nor sensitive, but they are useful in determining approximate wet-film thickness of coatings on articles where size and shape prohibit the use of more precise methods. (ASTM D1212).

The gauge should be used on smooth surfaces, free from irregularities and should be used along the length, not the width, of curved surfaces. Using a wet-film gauge on quick-drying coatings will yield inaccurate measurements. ASTM D4414 outlines a standard method for measurement of wet-film thickness by notch gauges.

A wet film wheel (eccentric roller) uses three disks. The gauge is rolled in the wet film until the center disk touches the wet film. The point where it makes contact provides the wet film thickness.

Powder coatings can be measured prior to curing with a simple hand-held comb or an ultrasonic gauge. The uncured powder film comb works much the same way as wet film gauge. The comb is dragged through the powder film and the thickness lies between the highest numbered tooth which made a mark and has powder clinging to it, and the next highest tooth which left no mark and has no powder clinging to it. These gauges are relatively inexpensive with accuracy of ±5mm. They are only suitable as a guide since the cured film may be different after flow. Marks left by the gauge may affect the characteristics of the cured film.

An ultrasonic device can be used non-destructively on uncured powder on smooth metallic surfaces to predict the thickness of the cured film. The probe is positioned a short distance from the surface to be measured and a reading is displayed on the LCD of the device. Measurement uncertainty is ±5mm.

About the Author

David Beamish is the general manager of Defelsko Corporation, a New-York based manufacturer of hand-held coating test instruments sold worldwide. He has a degree in Civil Engineering and has more than 17 years experience in the design, manufacture, and marketing of these testing instruments in a variety of international industries including industrial painting, quality inspection, and manufacturing. He conducts training seminars and is an active member of various organizations including NACE, SSPC, ASTM and ISO.

You can find a full product range of Defelsko Thickness Gauges on GlobalTestSupply.com.

Ampere – a unit of measure for the rate of current flow.

Apparent power – applied voltage multiplied by current in an AC circuit. This value would not take the power factor into account. Unit is voltamperes (VA).

Balanced load – AC power system using more than two wires, where the current and voltage are of equal value in each energized conductor.

Bandwidth – the range of frequencies over which an instrument provides accurate measurement.

Billing consumption – total amount of energy consumed during a predetermined period (usually 28 to 33 days)

Consumption (active energy) – actual electrical energy used measured in kilowatthours (kWh) by the watthour meter, regardless of the power factor.

Crest factor – the ratio of the peak value of a waveform (voltage or current) to the RMS value.

Current transformer – an instrument accessory which detect current flow without breaking the circuit under test. An AC transformer, usually step-down; typical ratio would be 1000:1. This would indicate 1000A on the primary and 1A on the secondary.

Current transformer ratio – the ratio of primary amperes divided by secondary amperes.

Delta Connection – a circuit formed by connecting three electrical devices in series to form a closed loop; most often used in three-phase connections.

Demand (active, real, or true power) – the power which is actually consumed by the load. This measurement takes the power factor into account.

Demand interval (integration period) – the period of time over which the energy is averaged. Typical demand intervals are 15, 30, or 60 minutes.

Derating Factor – a number defined as 1.414 x  average RMS phase current/peak phase current. This factor, when applied to the rated load of a transformer, gives an indication as to the percent loading that is reasonable when that transformer must service nonlinear loads.

Displacement Power Factor – the difference between apparent power and true power when only the phase relationship of voltage and current at the fundamental are taken into account.

Distortion Factor (%DF) – Total harmonic distortion referenced to the total RMS signal (THD-R).

Distortion Power Factor – the difference between apparent power and true power at all harmonic frequencies.

Frequency – the number of complete cycles of AC voltage which occurs during one second (Hz).

Harmonics – current or voltages which have frequencies that are integer multiples of the fundamental power frequency; common and some times dangerous in nonlinear loads.

Heating effect – temperature increase in electrical distribution equipment caused by an increase in RMS current.

Impedance – the total opposition to alternating current flow in an electrical circuit (Z).

Inductive Reactance – the force which acts as a resistance in an inductor to limit the flow of current. This force creates a leading power factor in AC circuits.

Initiator pulses – electrical impulses generated from utitliy revenue meters. Each pulse indicates a specific number of watts consumed. These pluses are used within energy analyzers to measure energy consumption and demand.

K factor – a number based on the harmonic content of load current that determines the maximum safe loading on a power source.

K-rated transformers – a transformer that is rated or designed to serve as the source for a predefined capacity of harmonic current.

Peak demand (maximum RMS power) – the highest average load during a specified time interval (kW).

Phase – time relationship between current and voltage in AC circuits.

Potential transformer – an instrument transformer used to step down high voltage potentials to lower levels acceptable for the input of electrical test instruments.

Power factor – the ratio of true power (watts) to apparent power (voltamperes). Expressed in decimal form.

Ratchet demand – determining the billing demand based upon a pre-established peak average demand (usually at 75%, 80%, or 100% of the pre-established peak).

Reactance – the opposition to current flow in an AC circuit introduced through inductance or capacitance.

Reactive compensation power – the reactive power to be applied to an AC network for power factor correction; adding capacitance in order to bring the voltage and current waveform in phase.

Reactive power (kvar) – power which is actually “borrowed” from the load and returned to the power source each cycle; unused power.

Resolution – the smallest unit value that an instrument can measure

Resonance – when the inductance in the system and the natural capacitance of the system, or added capacitors, form a tuned circuit resonant at one or more of the harmonic frequencies produced by nonlinear loads.

RS-232 – a computer interface connector used to connect serial devices such as instruments for information transfer.

Sensitivity – the smallest input that will provide a specified output.

Skin effect – phenomenon in which high harmonic frequencies cause electrons to flow to the outer sides of a conductor, reducing its cross-sectional diameter, ad hence its ampacity rating.

Sliding demand – calculating average demand by averaging the average demand over several successive time intervals, advancing one interval at a time.

THD (%THD, Total Harmonic Distortion) – the contribution of all harmonic frequency currents or voltages to the fundamental current or voltage, expressed as a percentage of the fundamental.

THDF (Transformer Harmonic Derating Factor) – method of calculating transformer derating established by CBEMA for phase-to-neutral loads.

True RMS – capability to accurately measure the value of AC voltage and current having a nonsinusoidal waveform as well as sinusoidal waveforms.

Unbalanced load – an AC power system using more than two wires, where the current is not equal in the current-carrying wires due to an uneven loading of the phases.

Watt – the measure of real power. It is the power expended when one ampere of direct current flows through a resistance of one ohm.

Wye connection – a connection of three components made in such as manner that one end of each component is connected; generally used to connect devices to  a three-phase power system.

As with many serial data systems, both ARINC 429 and MIL-STD-1553 are differential busses. ARINC 429 is the simpler and less costly of the two. The physical connection is via twisted pair wires with balanced differential signals. It uses a self clocking, self synchronizing data bus. MIL-STD-1553 uses dual redundant balanced differential pairs. The peak to peak voltage allowed in the differential pair of an ARINC 429 system is 10 volts whereas the peak to peak output voltage of a transmitter on the MIL-STD-1553 bus is allowed to be as high as 18-27 volts. Both systems are designed for noise immunity and signal integrity. Among the plethora
of modern serial data standards, both avionics busses are fairly low speed compared to PCI-Express, SAS or other standards which transport large amounts of data over short distances inside personal computers.

Capturing and Viewing Signals

Since the edge rates of signals and the command/data transmission rate of the busses is moderate, an engineer working on a system using ARINC 429 or MIL-STD-1553 does not need the type of very expensive oscilloscope used to capture signals sent on multi gigabit per second busses. The WaveSurfer and WaveRunner classes of oscilloscopes from LeCroy are well matched to this application. The images used in this paper to illustrate capturing, viewing, decoding and troubleshooting signals were gathered using those types of oscilloscopes. Figure 1 shows a typical example of serial data decoding. Though this particular image shows MIL-STD-1553, the decoding of many types of serial data looks very similar. Rather than the engineer spending a large amount of time peering at the shape of a serial data signal on his oscilloscope screen, counting highs/lows and decoding the data in his head the oscilloscope can highlight different portions of the signal content with different background colors, digitally decode the data and display the resulting digital interpretation along with the analog shape of the electrical waveform from the bus. This not only saves the engineer considerable time in developing a new product (or trouble shooting a problem), it also greatly reduces the chance of human error in “eyeball interpretation” of the signal shape. Note that in Figure 1 the upper trace is at longer time/division. It shows more signal length, but with less detail than the lower trace, which is a zoom of the upper trace.

Figure 1: A MIL-STD-1553 signal is viewed and decoded on the upper trace. The lower trace shows a zoomed portion of the upper signal. Note the zoom has a more detailed level of decoding.

In addition to seeing the voltage vs time trace in more detail in the zoom view, the oscilloscope also shows more details of the decoding of the signal. This type of zooming to get more detail is particularly useful in modern digital oscilloscopes which have long data acquisition memory lengths and hence have the ability to capture more signal details than will conveniently fit onto the pixels of a typical flat panel display.

Using the Decoded Signal

Sometimes the engineer can get all the information he needs to confirm proper operation of a circuit or device by viewing the decoded signal. But more often the engineer needs to examine a long signal acquisition or even many acquisitions in order to spot problems or to characterize correct device operation. Figure 2 is an example of the view and decode of an ARINC 429 signal. It is somewhat similar to Figure 1; the upper trace shows one second of signal shape ( 10 divisions of the oscilloscope screen at 100 msec/div) and the lower trace is a zoom detail of that data. As with Figure 1 the zoom trace shows more detail of the voltage vs time trace and also more detail of the decoding of the data. There is a further feature at the bottom of Figure 2 – a table which lists important attributes of the serial data stream. The table can inform the oscilloscope user of important characteristics of the whole signal without him needing to zoom in and look at each piece of the signal in detail. By examining the table the user can find the pieces of the signal that are of the most interest, click on the entry in the table and the scope will automatically zoom to that portion of the signal.

Figure 2: The capture of an ARINC 429 signal on the upper trace, a zoomed portion on the same signal on the lower trace and a table showing key signal characteristics.

Identifying and Trouble Shooting Problems

At the R&D stage every project suffers from some sorts of problems. In an avionics system it is particularly important to identify any potential pitfalls either in the data/command transmission system or in the devices which communicate via that system. The ARINC 429 option from LeCroy allows an oscilloscope user to search a captured signal record using a choice of 14 selectable criteria. These include the time of occurrence of a portion of the captured signal, data value, parity, message, status and other signal attributes. The MIL-STD-1553 option goes one step further and allows the scope user to set up a trigger to capture and decode exactly the portion of the signal in which the user is interested. Figure 3 shows the trigger setup menu where the user can choose the type (transfer, word, error and timing), subtype (command, data, status, any), format (binary, hex) and command. The oscilloscope will then monitor the live signal coming into the specified channel of the scope and trigger on the desired type of signal. As examples, being able to trigger on a specific command or being able to monitor the signal and trigger on any error are very powerful ways of testing and debugging problems.

Figure 3: Setting up a trigger for MIL-STD-1553. The user can select the type, subtype, format and command.

Summary

Modern digital oscilloscopes can greatly speed product development time and minimize the possibility of glitches in aerospace systems. In addition to capturing and decoding avionics specific signals such as ARINC 429 and MIL-STD-1553 it is also possible to do the same sort signal acquisition, decode and trouble shooting on ubiquitous signals such as USB, RS232, UARTs, and a wide variety of other types of serial data.

For more information on Lecroy Oscillocopes – click here: Lecroy

Written by: Dr. Michael Lauterbach
January 11, 2012

In some ways, induction lamps are a subset of fluorescent lamps. The light emitted from the lamp comes by transferring the energy from ultraviolet waves (UV) to a fluorescent coating on the inside of the bulb. The fluorescent coating converts the UV into visible light and the glass wall of the bulb absorbs any remaining UV. So only the visible light is emitted. The coloration of the light depends on the types of fluorescent used to coat the inside of the bulb.

But the method of producing the UV in typical fluorescent lamps is much different than the process used by induction lamps. UV is produced by establishing an arc discharge. In the case of the conventional fluorescent lamps the arc termination is at tungsten filaments (electrodes) at each end of the tube. An electrical current sustains the arc. The electrons in the arc through the lamp stimulate mercury vapor in the lamp thereby producing the UV waves that in turn excite the phosphor. Once the lamp starts up, it becomes a device with negative resistance – the more current that flows in the lamp, the lower its resistance becomes. So a ballast is required to moderate the flow of energy.

By contrast, induction lamps do not have filaments. This is also a huge difference from conventional fluorescent bulbs where the arc goes from one electrode to the other. The induction lamp has one continuous arc, eliminating the need for the wear out electrodes. Induction lamps work on the same principle as transformers, commonly encountered by electronic design engineers in power supplies. An alternating current passing through a conductor (the “primary:) will generate a magnetic field whose strength varies with the amount of current. The time varying magnetic field will induce a current in a nearby conductor (the “secondary”).

In the case of induction lamps, the 50-60 cycle AC line current is stepped up to RF frequencies. The wire carrying the RF signal is wrapped around a ferrite core that is exterior to a bulb containing mercury gas. The wire wound core acts as the primary of a transformer and the gas is the secondary. The energy transferred by this process excites the gas and it starts to emit UV. An electronic ballast is used to control the start-up and steady state operation of the bulb. These types of lighting devices can be highly efficient and long lasting. Efficiency is rated in lumens of light output per watt of power consumed.

An Example of Testing an Induction Lamp

Both the efficiency and the longevity of an induction lamp depend crucially on the ballast used to control it. In many cases this is a microprocessor controlled circuit – and considerable design and test expertise is needed to create a reliable, low cost yet effective ballast. Typically, a lighting device needs to operate in AC circuits with voltages ranging from 108 to 270 volts and frequencies of 50-60Hz. Figure 1 shows an example of testing on an induction lamp. In this case, the lamp ignition is having a hard time starting. The input voltage is 277 volts. This should be stepped up to about 450 volts and 200 kHz to operate the lamp. The upper half of the oscilloscope screen shows the capture of four signals over the course of one second during start up. Note the time/div in the lower right corner is 100 ms/div and there are ten horizontal divisions on the screen. The lower portion of the screen shows a zoomed detail at 20 ms/div of the four upper traces – basically, the zoom shows the portion of the signal captured in the 2nd and 3rd horizontal divisions of the upper grid. In the upper grid you can see highlighting on the early portion of the signal which indicates which piece of the signal is being shown in the zoom.

Figure 1: Failed ignition of an induction lamp operating at 277 volts. The upper grid shows one second of capture time for four signals. The  highlighted portions of those signals are shown as zoom details in the lower grid. Channel 1 (orange) is the rail voltage, Channel 2 (red) is the boost diode current, channel 3 (blue) is the bias supply voltage and channel 4 (green) is the output voltage of the lamp.

Channel 1 (orange) is the rail voltage which should be boosted to 450 volts. Note in the lower left corner of the screen the sensitivity of channel 1 is 100 Volts/div. In the highlighted portion of the lamp start up channel 1 only reaches (just barely) the fourth division, 400 volts. If you examine the upper trace you can see it reaches 450 volts about half a division later. Channel 2 (red) is the boost diode current (5 amps/div). For proper operation of the lamp, it should be running at a frequency of 100 kHz. In the zoomed detail you can see channel 2 is starting to switch current, but at a much slower rate than 100 kHz. Channel 3 (blue) is showing the charging of the internal bias supply to run the electronics (5 volts/div). It needs to be above 10 volts and though it eventually does get there (as shown in the upper trace), during the start-up portion of the signal shown in the zoom it never reaches 10 volts. Consequently, channel 4 (green) of the oscilloscope (1 kV/div) which shows the output voltage of the lamp reveals the lamp tries to start up and then fails.

Perhaps the first lesson concerning testing of induction lamps is that you need several types of probes to acquire the signals. Channel 3 i “easy”, just 5 volts/division so the typical probe supplied with the scope can handle it. For channels 1 and 4 the signals have much higher voltages so specialized voltage probes may be required. Channel 2 is a current ignal, so you either need a hunt to convert the current signal to a voltage or you need to use a current probe capable of capturing AC currents at frequencies up to at least 200 kHz.

When you want to use an oscilloscope to examine multiple signals and multiple zooms or multiple math traces it is good practice to use multiple grids. The ADC (analog to digital converter) on the front end of a typical 8 bit oscilloscope has 1 part in 256 resolution to measure the amplitude of the signal. If a ope is set up to display many signals on a single grid the user “squashes” each signal to fit a small vertical portion of the grid. Since the ADC is spreading its dynamic range across the full vertical height of the grid, if a ope user place a signal to fit into one vertical division (in order to see 8 signal shapes on a single grid) the scope winds up using only one eighth of its codes, 32 counts, to digitize the signal. Essentially, the user has paid for eight bit ADCs but is only using hem as 5 bit ADCs. Note in the upper grid on Figure 1 that each of the four signals is occupying about half of the vertical range of that grid – which means the four signals are each being digitized using half of the vertical range of the ADC. In an optimal case, the user would want the signals to cover near the full range of the grid, but in actual engineering practice, some headroom often needs to be left in case the signal goes higher or lower than expected. Also, in this case, no precision measurement is needed. The scope is operating more as a simple viewing tool. The shapes of the signals are enough to confirm the lamp is not operating properly.

Second Example of Induction Lamp Testing

A second example of testing the same induction lamp is shown in Figure 2. This time the basic operating conditions are 208 volts and 60Hz. The ignition sequence is better than in Figure 1 but still not sufficient to get the lamp started during the one second of time captured by the oscilloscope. The four traces (and the four zooms) are all still the same signals as in Figure 1, the horizontal time base of the acquisition and the zoom are the same and the vertical sensitivities (volts/div and current/div) are also the same as in Figure 1. The highlighted
area of the upper traces is now the 4th and 5th horizontal divisions of the upper grid. You can see the orange trace on channel 1, the rail voltage, reaches 300 volts near the end of the first horizontal division on the upper grid and eventually gets to the targeted 450 volts near the end of the zoom portion. But during the crucial time where the
lamp is starting up (as shown in the green trace on channel 4) the rail voltage oscillates at around 300 volts. Channel 2, in red, shows the boost diode current attains a much higher frequency than in Figure 1. In the zoom you can see a comb shape of quickly changing diode current. Channel 3 (blue), attains the 10 volts desired for the bias supply charging voltage shortly after the third division on the upper grid. But as the light starts to turn on (channel 4, the green trace) the bias voltage is disrupted. You can see bursts of noise on channel 3 which line up with the bursts of current on channel 2. The lamp fails to stay on and all four signal collapse back to steady states.

Figure 2: The same test setup as Figure 1 but this time the input voltage is 208 volts rather than 277 volts.

In addition to the oscilloscope usage lessons discussed above in the first example there are a few new points that arise. In Figure 1 the activity of the boost diode current could be clearly seen as nine fairly slow peaks of roughly triangular shape. But in Figure 2 the same signal has much faster activity. This could be viewed more clearly if channel 2 was zoomed to a faster time base. Some oscilloscopes only allow one common timebase for all zoom traces, as is shown in both figures. But in many real world test situations there are both slow signals and faster ones. So it can be desirable to have multiple zoom timebases. Many LeCroy oscilloscopes have this capability. You can even have a zoom of a zoom – perhaps turning on a 3rd and 4th grid that showed just the green and red traces on faster timebases than the existing zoom. That is a useful tool for viewing details of multiple signals. And there is a useful technique for measurements in this situation. Is the boost diode current running at its desired 200 kHz ? You can’t tell from Figure 2. But if the scope was set up to show the boost diode current on a third grid, at a faster zoom display timebase you could visually ascertain the frequency , you could do an FFT of the faster zoom trace or apply a parameter measurement to that trace. Using a zoom to select of portion of a waveform for measurement is a good technique. If you want to ignore a portion of a signal and just do math or
parameter measurements on a piece of the signal, you can activate a zoom to select the interesting portion of the signal, then apply math or parameters to the zoom trace (only).

A similar sort of capability with respect to measuring parameter values on just a portion of the signal can be accomplished using a feature called a “measure gate.” Oscilloscopes with this feature (including many LeCroy oscilloscopes) allow the user to turn on two vertical cursors and use them to define the piece of the signal to use in making parameter measurements. The measure gate can be placed on the original acquisition channels or it can be placed on a zoom. In both Figure 1 and Figure 2 the user has placed a measure gate on the lower grid.

In Figure 1 the vertical dashed, black lines can be seen to line up with the start and end of the burst of activity on the green trace (the lamp output voltage). In Figure 2 the measure gate is noticeably inside the envelope of lamp activity. The oscilloscope user can even move the measure gate to see if parameter values are different on various portions of the signal. Is the diode switching frequency (red trace) the same in the first burst of activity as 2nd, 3rd, etc?

There is one final point. Suppose you have the lamp shown in Figures 1 and 2 – and when you flip a switch it turns on? Certainly the view shown of the signals during one second of acquisition time does not look good. But maybe after the circuit has a few aborted tries it starts to work and the ballast regulates the light. What you might need is an oscilloscope with a longer acquisition memory in order to record the complete action of the lamp. If you look at rectangle near the lower right corner of both Figure 1 and 2 you can see the oscilloscope is capturing “10.0 MS” which means ten million samples of data on each of the four input channels. You can also see the sampling rate is “10 MS/s” – 10 million samples per second. This sample rate is clearly a good one for capturing the sort of details in this application. Let’s suppose you could keep the sampling rate the same, but instead of capturing one second of data you would like to capture for three seconds. You would need 30 million sample points. There are a couple of ways to do this. Some oscilloscopes have very long memory and you can simply go into the horizontal setup menu and tell the oscilloscope to use more. In other cases, you can sacrifice the number of input channels acquiring data in order to have longer memory available for the channels that are in use. An example is the WaveSurfer MXs-B from LeCroy (though there are also many other types of scopes with this capability). If you use all four channels of this type of scope, there are 16 Mpts of memory per channel. But the scope can also be told to operate in 2 channel mode and apply 32 Mpts of memory to each channel. So you could capture 3.2 seconds of data on 2 channels at 10 MS/s sampling rate. In order to test the operation of your lamp, maybe you only really need to see channel one and channel two of the two previous examples. Or, if desired, you could capture two signals, save them to internal memory in the scope, then capture two more signals. So you could even have all four signals – but use two acquisitions to acquire them.

Summary

There are many different types of interesting and useful lighting devices. To obtain longer lasting and more efficient lighting, good R&D engineering and careful testing are needed. This necessitates a wide variety of probes and can be enhanced by a knowledge of how to use the measurement capabilities of oscilloscopes.

See Lecroys full product line of oscilloscopes here: Lecroy Store

Written by: Dr. Michael Lauterbach
January 18, 2012

To accomplish this task you need a ground resistance test instrument capable of testing using four electrodes commonly referred to as a four point or four pole tester. You also need four auxiliary electrodes and four spools of wire.

Next you need to decide on which test method to employ. There are two methods that are commonly used, the Wenner and the Schlumberger. Of these two, the Wenner method is the most popular and easier to use for testing soil resistivity for a grounding electrode system. The Schlumberger method is more practical to use when the task is to pot soil resistivity at several different depths, a requirement popular with geological surveying. In either method the results are represented by the Greek letter Rho (ρ) and are expressed in Ohm-Meters or Ohm-Centimeters representing the resistance of a cubic meter of soil. For this application note we will concentrate on the Wenner method. If we observe one simple condition we can apply a very simple formula to obtain soil resistivity. This condition will be explained later.

The simplified formula is ρ=2πAR.

Where:

ρ=ohm-cm

π is a constant = to 3.1414

A=the spacing of the electrodes (in centimeters will save time in obtaining the results without having to do a conversion)

R=the resistance value of the test in ohms

Before we get to the actual test, first let’s look at soil composition. Soils made up of ashes, shale or loam tend to have the lowest soil resistivity. Soils made up of gravel, sand or stone have the highest soil resistivity.

Moisture content, temperature and salts also affect soil resistivity. Soil that contains 10% moisture by weight will as much as five times lower soil resistivity than that which contains 2.5%. Soil at room temperature will be as much as four times lower in resistivity than that at 32 degrees. So the time of year that you conduct the test can play a major role in the results. Finally salt content factors in the results in a big way. Just changing the composition by 1% can reduce soil resistivity by as much as a factor of 20. Therefore a quick visual analysis of the job site can give you a good idea as to whether you can expect low resistance from the installed gorunding electrode system made up of a single ground rode or if you will need to install several rods to achieve the needed results. These conditions should be written down and kept with the test results. Temperature, moisture and soil type are easily identified. Salt content may be more difficult to determine.

Now we are ready to take some measurements. As most commercially available ground rods are 8 to 10 feet long, it makes sense to check the expected soil resistivity at a depth of 10 feet. Checking it 20 feet is a also a good idea for comparison.

Using the Wenner method you need to space the four electrodes out an equal distance from each other in a straight line and spacing equal to the depth to be tested. If we are testing at a 10 foot depth then the four electrodes need to be spaced in a straight line 10 feet apart. If we are testing at a 20 foot depth then the electrodes need to be spaced 20 feet apart and so on.

To get a good indication of soil resistivity of the grounding electrode site we should take five measurements and average them for the final answer. We should take them in a square pattern and then one on an inside diagonal of the square.

Now to use the simplified formula described earlier we need to observe one rule. That is the depth of the test electrodes should be no more than 1/20th the spacing of the rods. For testing at a ten foot depth the electrodes should be placed no more than 6 inches in the ground. No need to drive deeper for longer spacing.

Our rods are spaced 10 feet apart and only six inches in the ground. The instrument is ready to be connected to the rod. We must connect the terminals of the instrument in sequence to the rod using the spools of wire provided. Once the connections are made we can run the test. Turn the instrument on, place the selector switch in the soil resistivity test position and press the test button. Observe and write down the resistance reading measured. Do the same for each of the 5 measurements. For our test example let’s assume that our average for the 5 measurements was 3.4 ohms.

Now apply the formula:

ρ=2πAR=2(3.1414), (305cm)(3.4)=6515 ohm-cm

Notice we converted 10 feet to 305 centimeters to simplify our math. (10×30.5)=305

Lets look at the process of calculating the depth needed for a new ground rod installation. For this we will  use a calculating tool called a nomograph.

To begin with we need to make a few decisions. First what is the desired grounding electrode resistance needed? Second what is the diameter of the ground rods we will be using? With these two answers plus the measured soil resistivity we can use the nomograph to calculate the depth required to achieve our objective. Let’s say we need a resistance from this grounding system to be no more than 10 ohms and that we chose ground rods that have a 5/8 inch diameter.

Looking at our noograph, we have five scales to work with: the R scale represents the desired resistance needed, for our work (10 ohms). The P scale represents soil resistivity. Our average value is 6515 ohm-centimeters obtained using a 4 pole ground resistance tester employing the Wenner test method. The D scale represents depth and is what we will use to find our answer. The K scale contains constants that will assist us in finding the depth. Lastly the DIA represents the diameter of the rods used. We will complete several simple steps to get our depth answer.

Using the nomograph we first put a dot at 10 ohms on the R scale as it is our desired resistance.

Next we put a dot at 6515 on the P scale representing our soil resistivity measurement. We will have to do our best to approximate the location of this point between the 5000 and 10000 hash marks.

Next we take a straightedge and draw a line between the dots we placed on the R and P scales and let the line intersect with the K scale and place a dot on the intersecting point.

Now we again take a straightededge and draw a line between the dots we placed on the R and P scales and let the line intersect with the K scale and place a dot on the intersecting point.

Now we again take a straightedge and draw a line from the 5/8 hash mark on the DIA scale representing our rod diameter through the dot on the K scale and continue through to intersect with the D scale and place a dot on the D scale at this intersecting point.

A nomograph is a mathematical tool consisting of several nonlinear scales on which known values can be plotted and the desired unknown value can be derived by simply connecting the points with a straightedge and finding the resultant by reading the intersecting point on the desired scale. In the case of grounding resistance, we will be dealing with known values for soil resistivity, rod diameter and desired system ground resistance. The unknown to solve for is the depth needed to achieve the desired resistance. The grounding nomograph was developed in 1936 by H.B. Dwight.

In six simple steps, depth can be calculated when the soil resistivity, rod diameter and desired resistance is known.

1. select the required resistance on the R scale
2. select the measured soil resistivity on the P scale
3. take a straightedge and draw a line between the values placed on the R and P scales and elt the line intersect with the K scale
4. place a dot at the intersecting point on the K scale
5. place a dot on the desired rod diameter

A daunting range of products are available to reduce ESD in your environment. For the first-time purchaser especially, it is easy to become unsure of which solutions are best for your specific situation. The answer to this is to follow a problem-solving process, rather than concentrate on each possible product. What does such a process look like?

To successfully reduce ESD in your environment, you must apply some Operations Management skills. First, you will investigate your environment. Second, you’ll review your processes. Only then will the most appropriate solutions to ESD reduction be clear. At that point, you will be able to intelligently apply products to your environment with the following variables in mind:

• the level of risk you’re willing to accept
• your budget for ESD countermeasures
• your countermeasure knowledge.

Investigate Your Environment

Potential ESD risks always exist. Look carefully at your work environment. Are people permitted to casually walk in and out of the area which needs to be protected? Are they leaving food, papers or plastic items on work benches? Do you see creams or solvent cleaners around? These are all high ESD hazards and must be removed.

Relative humidity within the workplace can also be a static charge buildup risk. If this is not above 40% relative humidity, the static buildup can be high and stored charges will exist on nonconductors. Once the physical sources of ESD risk have been taken out of the work environment, you may want to proactively (rather than reactively) continue by using an ionized air blower. These blowers neutralize conductive surfaces by blowing positive and negative ions over them at the same time.

ESD caution signage is available. Make sure these are put up in your workplace, and that everyone understands their meaning.

Review & Improve Your Processes

Flowchart and review your work processes. Are there any steps which could be shortened or eliminated? Material handling in particular creates significantly increased risk of ESD events. Soldering guns are another risk because of emitted heat and split solder. You can improve your processes so that soldering guns are removed from the work surface at appropriate times. Any time someone is going to handle an integrated circuit, they must be grounded. Wrist straps, floor mats and footwear sole grounders are available to accomplish this. You can use them individually or layer them to increase protection levels.

Material handling is obviously impossible to completely eliminate from the manufacturing process. However, various means of protecting items during transit are available. Items can be plaed under covers or within liners. They may be put in bags or containers. Special kinds of tapes, labels and even lotions are also available that reduce ESD risk.  Depending on your budget, a variety of these may be best suited to mitigate ESD in  your environment.

The most active feedback of ESD risk comes in the form of two devices: workstation ESD monitor or grounding tester.

Workstation ESD monitors are very helpful when diagnosing and troubleshooting static control problems. They will measure variables such as:

• ESD events and, depending on the model, what parts have been damaged
• Static voltage
• Ionization balance
• Ionization decay.

Grounding testers monitor key indicators including:

• if wrist straps have been properly plugged in
• the body voltage of the operator
• whether work surfaces and tools are correctly grounded.

Ensure that work surfaces and grounded connections are inspected for compliance with your new ESD risk minimization standards at least once per day. All of these actions are products used intelligently in combination will significantly reduce ESD hazards in your environment.

For a FREE ESD Evaluation of your work area, call Global Test Supply at 888-610-7664 to setup an appointment.

You are welcome to publish this article for free of charge on your website, newsletter or e-zine provided:

• You do not alter the article in any way,
• You include the entire article, including the About the author section,
• All hyperlinks remain intact,
• You agree to indemnify the author,
• You provide a courtesy copy of your publication to the author.

Jason Kanigan is a technical writer for Global Test Supply, a distributor of test and measurement equipment.

Clearly illustrated here are two fundamentals concerning calibration:

1. Without a calibration system, both output and measurement tools will drift off target over time
2. The results of failing to calibrate correctly and consistently are large losses of money, time and effectiveness.

Assuming you’re not in the Navy, what consequences of ignoring calibration of your equipment can you expect? Products being tested could be accepted when they are bad, and rejected when they are good. Inaccurate readings can lead you in a false direction in research, product development or troubleshooting. A contractual agreement may state that your output has to be within specific tolerances, and ignoring calibration may result in the customer breaking the contract, issuing fines, revoking your operating license or other punishment. Consumer and employee safety may be threatened. The environment could be damaged by emissions. Nielsen research and ATS (in 2006 and 2008) averaged the cost of manufacturers’ calibration errors to be over $1.7 billion each year.

Calibration requires a known standard of accuracy. The performance of an instrument is compared to this known standard, and adjusted back to conformance. You do this after the power goes out at your home. When electric service returns, you find a clock that you know is displaying the correct time, and then go around resetting all the flashing clocks in the house. The reading provided by all of the clocks is then known to be accurate – or, accurate enough for your tolerances.

However, testing one instrument against another is not calibration. This is called field testing. Both instruments could be out of calibration by the same amount and direction, and you would learn nothing. Also, you would not know which instrument read correctly. You must have a standard which you know is accurate, and the most proper calibration procedure has a chain of information that links it back to a maser standard at the National Institute of Standards and Technology (NIST). A minimum accuracy of ten times the accuracy of the equipment being tested is required for a calibration standard. This way, calibration within overlapping tolerances is not possible and the equipment will assuredly be calibrated correctly.

What causes things to shift out of calibration tolerances? Most components degrade over time – some very quickly, some over long periods. A calibration schedule is usually what discovers and corrects this drifting. Many items can go out of calibration because of shock: from being dropped, for example. Some can be overloaded by electricity which knocks out protective devices, causing damage to reading meters.

Calibration testing must therefore be completed:

• When the manufacturer recommends
• When the work to be done specifies
• Before and after an important testing or measuring task
• After a physical shock or electrical event
• At regularly scheduled intervals (annually, quarterly, monthly)

Calibration often requires sending the equipment to a service depot or back to the manufacturer. They will calibrate it using NIST-certified standards. Keeping employees and consumers safe, controlling emissions, considerably reducing production and rework costs, saving time, ensuring quality measurements and output, and improving the effectiveness of results are all important reasons to calibrate your equipment and instruments.

You are welcome to publish this article for free of charge on your website, newsletter or e-zine provided:

• You do not alter this article in any way,
• You include the entire article, including the About the author section,
• All hyperlinks remain intact,
• You agree to indemnify the author,
• You provide a courtesy copy of your publication to the author.

Jason Kanigan is a technical writer for Global Test Supply, a distributor of test and measurement equipment.

As one of the world’s largest oilfield service companies, Weatherford is only too aware that oilfield operations present unique channgles as the hazardous and remote conditions make it difficult to carry out daily operational tasks.

Weatherford operates in more than 100 locations worldwide, with a product and service portfolio that spans the life cycle of a well – from drilling, evaluation, completions to well intervention. Photography and documenting images for surveys and reports is part and parcel of every day activities offshore.

The ToughPix 2303XP was well received by Weatherford staff who adopted the new digital camera in February 2011. The next-generation device is ATEX and American CSA certified to take images within Zone 1 IIC T4 and Class 1 Division I B, C, D hazardous areas.

This latest version of the ToughPIX 2303XP camera is more streamlined than its predecessor and includes still and moving images in AVI format of up to 10 megapixels. Encased in aluminum with an ultra-bright display protected by armoured glass, the revolutionary camera is custom designed for the harshest environments.

Mechanised Systems Engineer Michael Wilson, who is based in Aberdeen and the NOrth Sea regularly uses the ToughPIX 2303XP to capture images to help him carry out his job of ensuring oilfield equipment and work systems are running efficiently and safely.

Michael’s work entails carrying out pre-installation surveys which require high quality photographic coverage to show in-situ working environments and how operations are functioning. He deals with pressure vessels, pumps, control systems, boilers, heat exchangers, piping and all the things mechanical required to get his job done to ensure the integrity of company assets.

Michael said: “The ToughPIX has been invaluable over the last few months. It has cut out the requirement for hot permits and reduced time-consuming paper work. Offshore you will simply not be given a permit to use a camera outside of the accommodation module unless it is for a specific work related activity. When using a camera you have to do a risk assessment to identify the hazards and severity by using it. With traditional digital cameras the battery is a source of ignition in a zone 1 or 2 area and the flash can set off the UV flame detectors which could lead to fire & gas system activation so a gas monitor must be carried at all times and the flash taped over. The ToughPIX 2303XP is ATEX certified which cuts out all of this makes my job so much easier.”

Michael’s job is like putting together a puzzle, making sure that all offshore and onshore operational systems are working together to perform a desired function. As a systems engineer he is concerned with the ‘big picture’ of a project, and in addition to technical aspects he must consider details like manufacturing, scheduling, testing, installation associated with engineering and scheduled maintenance projects.

Michael uses the ToughPIX 2303XP to provide visual documentation to support his work. He explained: “It is necessary to back up surveys and reports with photographic evidence to show machinery working in complex systems and running smoothly. The camera has proved very reliable and has helped in allowing critical decisions to be made, when systems are not working or problems occur. With its onboard 8GB memory, it has allowed me to store hundreds of images which can be easily downloaded to any PC.”

“The LCD screen lets you view pictures in the field and the inbuilt safety flash is ideal when photographing in low lighted areas. It is simple to use with large easy to press buttons and robust and sturdy enough to survive a few bumps and knocks.”

Teesside headquartered CorDEX Instruments has launched a series of ATEX and Intrinsically Safe certified products to the energy sector.

Company Director Marcus Halliday said: “We have refined our digital cameras range following feedback from the industry and the feedback has been excellent. Saving time in the field when you go offshore is all important and ToughPIX 2303XP does exactly that. They are as easy to use as an every day camera with all the functions you would expect from a high-end model.”

CorDEX Instruments has also developed CAMS – CorDEX Assest Management Software – a desktop package that boosts the capabilities of ToughPIX 2300XP Series cameras and included as a complimentary ‘add-on’ package for customers.

CAMS allows users to exclusively organize and manage information and images taken in the field with the ToughPIX 2300XP Series. It can generate reports and quickly manipulate images downloaded onto the system. Users can simply download images, edit then instantly annotate to produce reports.

With offices in the UK and US, CorDEX Instruments has an expanding global distribution network.