An Essential Tool for Measuring Optical Power

The fiber optic power-meter is a test instrument for optical fiber power measurements as well as fiber optic loss related testing, an essential tool for measuring optical power within a fiber optic link. The current selection of hand held type fiber optic testers offer a wide range of power measurements with highly accurate precision, some with an automatic self-calibration function. The fiber optic power meter is a tool used for many optical fiber applications taking measurements across a broad range wavelengths from various power and energy sources. Power Meters are widely used by the Telecom and CATV sectors to support FTTx deployments, fiber network testing, certification reporting and of course the basic power measurements. Test Equipment Connection offers the widest selection of new and used power meters starting at $695 (Kingfisher KI3600-GE-MP).

The Kingfisher KI9600-InGaAs Optical Power Meter is optimized for single mode and CWDM applications offering 9 calibration wavelengths with 2% accuracy.

The JDSU OLP-6 optical power meter which has a very easy to use three-button operation and a bright, clear display. The reference level for the attenuation measurement is made to IEC-874-1 and can be saved with a single keystroke.

Wilcom’s T-339E is a ruggedized optical power meter that utilizes advanced microprocessor technology to provide for easy, accurate and stable calibration as well as error free, non volatile digital storage of reference measurements.

LeCroy Demo at the 2010 Embedded Systems Conference

LeCroy LogicStudio Logic Analyzers – Logic analyzers are known to be slow, complicated and expensive but Logic Studio changes all this by delivering a powerful feature set, high performance hardware and an intuitive point and click user-interface. With timing cursors, history mode, I2C, SPI and UART decoding, powerful triggering and simple navigation the PC is transformed in to an all-in-one debug machine. Pair the LogicStudio 16 with a WaveJet 300A oscilloscope and debug systems with analog, digital and serial data signals.

Unique Feature Set

From basic tools like timing cursors that snap to the edge of a waveform to protocol decoding of I2C, SPI and UART busses LogicStudio provides a rich feature set for faster, smarter debug. History mode will display previously captured data and the powerful, flexible triggering will help solve the most complicated problems.

Easy to Use

The intuitive user-interface works with basic mouse operations. To pan the waveforms simply click and drag, Use the mouse wheel to zoom in or scan the waveforms with the magnification toll to get a great view of the details. With all the debug tools accessible from the main screen, debugging is simple, efficient and just 1 mouse click away.

Digital, Serial, Analog

Turn the PC into a mixed signal oscilloscope by connecting both a LogicStudio 16 and a WaveJet 300A oscilloscope. View digital, serial and analog waveforms simultaneously, directly on the PC display. This combination of waveforms provides insight that a traditional logic analyzer cannot. 

Request Your Quote HERE

Get the Whole Picture Instead of No Picture

A temperature gun is a lightweight, easy-to-use tool for getting non-contact temperature readings, but what are you missing? With a thermal camera you don’t just get the temperature of one spot, you get an infrared image made of thousands of measurements that shows you exactly where the problem is. Infrared inspections save you time and money.

Why upgrade to an infrared camera?

• Save time and money: Find problems fast in one shot instead of painstakingly checking every inspection point one at a time.
• Increased safety: Get more information while standing at a safer distance from dangerous equipment and malfunctioning systems.
• Better inspections: A temperature gun just gives you an average temperature across a wide area, while a FLIR thermal camera gives you an accurate picture of possible problems so you can correct them right away.

Still using a temperature gun?

Upgrade to an affordable FLIR thermal camera for accurate, picture-perfect results at every inspection.

FLIR i5 Compact IR Camera

Features:

• Easy-to-use troubleshooting tool, pocket sized and fully automatic
• 80 x 80 pixels image resolution
• High accuracy of 2% helps you find problems faster and easier
• Large 2.8″ color LCD
• Double molded rugged design with easy grip handle construction meets IP43 dust/splashproof standards
• MiniSD card stores up to 5000 Radiometric JPEG format images
• Complete with 512MB miniSD Card, rechargeable battery, 110V AC adaptor/charger, USB cable, hand strap and protective hard carrying case
• Includes QuickReport software for analysis of radiometric images
• FLIR i5 Product Page

FLIR i40 Infrared Camera

Features:

• Advanced 120 x 120 detector – delivers 14,400 pixels resolution & thermal sensitivity that s higher than the competition.
• Free QuickReport software w/report templates to simplify your work.
• Easy camera controls, including emissivity & reflective temperature settings to help you troubleshoot with accuracy & confidence.
• High-powered illuminator that lights your way for safety and generates sharp visible-light images.
• 0.6 Megapixel visible camera.
• 2 year manufacturer’s warranty
• FLIR i40 Product Page

Thermal Cameras for Electrical & Mechanical Applications

The use of thermography has revolutionized predictive maintenance inspection programs for virtually all types of industries.

A thermal imaging camera is a reliable non contact instrument which is able to scan and visualize the temperature distribution of entire surfaces of machinery and electrical equipment quickly and accurately. Thermography programs have contributed to substantial cost savings for our customers around the world.

Free Function Generator & Arbitrary Waveform Generator Guidebook by BK Precision

Function and arbitrary waveform generators are among the most important and versatile pieces of electronic test equipment. In electronic design and troubleshooting, the circuit under scrutiny often requires a controllable signal to simulate its normal operation. The testing of physical systems and transducers often needs stable and reliable signals. The signal levels needed range from microvolts to tens of volts or more.

Download this Free Guidebook HERE (provided in the Adobe Acrobat PDF format)

BK Precision 4079 High Performance Function/Arbitrary Waveform Generator

The 4079 is a versatile high performance dual channel function / arbitrary waveform generator with the largest arbitrary memory depth in its class. The generator combines the ability to produce nearly any conceivable arbitrary waveform with accuracy and precision and a DDS architecture offering easy to use conventional function generator capabilities. Arbitrary waveforms have 14 bit amplitude resolution, 125 MSa/s sample rate and up to 4 million points of length. Waveforms can be output in continuous, triggered, gated or burst modes. The instrument can be remotely controlled via GPIB or RS232 using SCPI-compliant commands. Extensive features such as waveform summing, internal or external AM, FM and FSK modulation along with versatile sweep capabilities and variable edge pulse generation make this generator suitable for a wide range of applications including electronic design, sensor simulation and functional test.

BK Precision 4086AWG  Laboratory Grade Synthesized Function Generator

BK Precision 4086AWG is a laboratory grade synthesized function generator with arbitrary capability. Direct digital synthesis (DDS) techniques are used to create stable, accurate output signals for all 27 built-in standard and complex (arbitrary) waveforms as well as custom arbitrary waveforms. The 4086AWG produces high purity, low distortion sine waves up to 80 MHz, square waves up to 40 MHz and provides extensive analog modulation capabilities including AM, FM, FSK, PSK, pulse modulation, burst mode and linear/logarithmic sweep combined with multiple trigger modes. The included intuitive Windows Software lets users create and edit custom arbitrary waveforms and download them with a single click to the instrument’s non volatile memory. Unmatched affordability and high performance make the 4086AWG a perfect fit for many applications in Electronic Test and Design, Sensor Simulation and Education and Training.

with the Megger Structured Cable Testers and Fiber Optic Adapters

SCT Series
Structured Cable Tester
Certifies Category 7, 6a, 6 and 5e cabling
Exceeds Level IV Accuracy
1 to 1000 MHz frequency range

Most intuitive and easy to operate LAN certification tester on the market

Powerful diagnostics pinpoint the distance to link disturbances on each measured pair

Best return on your investment given low operating costs and superior reliability

The SCT Series is a high-performance tester for certifying and evaluating copper and fiber cabling installations.

The SCT Series are unmatched for flexibility with improved device features including 1/4 VGA color display, USB & serial ports; compact flash, secure digital, multimedia card storage, unit-to-unit audio and 64 Mb of internal memory.

Designed for cable installers and network owners who need to certify the performance of high-speed cabling to today’s industry standards and tomorrow’s emerging standards, the SCT Series delivers unmatched performance and accuracy.

Whether certifying cabling installations, troubleshooting problems, migrating to a high-speed network, or re-certifying after add-ins, moves or expansions, the SCT Series exceeds expectations.

Certify singlemode and multimode fiber optic links at 850, 1300, 1310 and 1550 nm wavelengths

Provide fully compliant Tier 1 Certification

Capabilities include length, loss and power measurements, power meter and light source

Perform bi-directional testing without swapping primary and secondary units

Integrated VFL for diagnosing link problems

Most intuitive and easy to operate fiber optic certification tester on the market

SCT-MMA  Fiber Optic Adapters
As the number of fiber optic links in the network increases it’s essential that your certification tester seamlessly certifies both copper and fiber, efficiently combining all media results together for analysis and reporting. The SCT-MMA and SCT-SMA fiber optic adapters fulfill this need by converting the SCT into a fully compliant Tier 1 multimode and singlemode fiber optic certification tester. Now you can confidently certify all of your copper and fiber optic links with the snap of an adapter.

The SCT fiber optic solution offers powerful capability and features including length measurement, two-fiber, dual-wavelength loss measurements, single and bi-directional fiber measurements, power meter mode, light source mode, Fiber-Map and visual fault locator (VFL) capability. The SCT Autotest differs from other units by returning a length measurement and four loss measurements when testing dual fibers.

Fully Compliant Tier 1 Certification
The SCT fiber optic adapters create a fully Tier 1 compliant testing solution measuring length, loss, and polarity.

The SCT also differs from some units by performing bi-directional testing on two fibers at two wavelengths without exchanging the Primary and Secondary units.

Testing Fiber and Copper is a Snap
Fiber optic and copper certification is a snap with the SCT. Switching between copper and fiber certification is faster and more reliable than any other solution, simply snap in an adapter. Only the SCT allows the user to create dual media projects that store all necessary copper and fiber optic certification parameters in one project. With dual media projects and the ability to automatically recognize copper and fiber optic adapters the SCT can seamlessly switch between copper and fiber optic testing and project parameters with the snap of an adapter.

Visual Fault Locator
The SCT fiber optic adapters include a visual fault locator (VFL) as an easy to use troubleshooting tool. The VFL can locate and visibly identify faults on fiber optic cables. The VFL features a 635-nm visible red laser source. The presence of the VFL’s red light indicates a trouble spot in the fiber such as a break or sharp bend. The VFL can be used with either multimode or singlemode fiber. The VFL creates a continuous or modulated light source powerful enough to escape from sharp bends and breaks in jacketed or bare fiber as well as poorly mated connectors, making it ideal for locating trouble spots in jumper cables, distribution frames, splice strays, patch panels, cable splice points and for tracing fiber

Research indicates that internal battery cell impedance increases with the age and discharge history of a cell. Since interruption in electrical service can spell disaster, a reliable backup power system is critical so that when conventional power fails, costly service outages can be avoided.

The BITE family of products provides meaningful data on battery health without significant expense or reduction in remaining battery capacity. The BITE products are designed for on-line ac impedance and dc terminal voltage measurement of secondary batteries.

The BITE 2 Battery Impedance Test Equipment determine the condition of lead-acid and nickel-cadmium cells up to 7000 Ah. An advanced feature set has been developed that includes Pass/Warning/Fail calculations based on a user-entered baseline value, advanced printing functions and more. The case of the BITE 2P consists of both the transmitter and a carrying case for all of the standard accessories and some of the optional accessories, in an all-in-one unit. The BITE 2 and its accessories fit into a sturdy canvas case with a shoulder strap.

The instruments work by applying a test current across the battery string while on-line, then measuring the total current (ac ripple + test current) and the voltage drop of each cell/jar. It then calculates the impedance. They also measure dc voltage and interconnection (strap) resistance to help determine the overall condition of the entire battery string’s electrical path from terminal plate to terminal plate.

The BITE 2 receiver stores the readings in its internal memory. These measurements, along with other maintenance data such as ambient and pilot cell temperatures and ac ripple current, assist in determining the overall condition of battery systems. Megger recommends that impedance measurements with the BITE 2 be made part of a battery maintenance program with readings taken and recorded semiannually for flooded batteries and quarterly for VRLA.

Unlike load cycle testing that involves substantial downtime and repeated discharges, using the instruments require no battery discharge, nor do they stress the battery in any way compared to other techniques. With a test time of less than 20 seconds for each cell and intercell connector, one person can easily, quickly, and precisely measure internal cell impedance, dc terminal voltage and intercell connection resistance without taking the battery system off line.

Chroma’s 63600 Series DC Electronic Loads are designed for testing multi-output AC/DC power supplies, DC/DC converters, chargers, batteries, adapters, and power electronic components. Excellent for research, development, production, and incoming inspection applications. The 63600′s state of the art design uses DSP technology to simulate non-linear loads using an unique CZ operation mode allowing realistic loading behavior. The 63600 series can draw its full rated current to almost zero volts. This unique feature guarantees the best loading performance for fuel cells and modern Point-of-Load devices.

In Search of the Zero-Ohm Load

High-wattage resistors often are used as test loads for power transformers. Resistors don’t introduce phase shifts, and it’s easy to check that a transformer’s voltage regulation remains within spec at different rms currents. The effect of various primary tap and secondary loading combinations also can be measured. On the other hand, actual loads don’t always have a constant resistance (CR) characteristic.

Many switching power supplies present a constant power (CP) load to the AC input. DC power supply outputs are intended to provide a constant voltage (CV) or constant current (CC) depending on the mode selected. To simulate anything other than simple CR, you need an electronic load.

Both AC and DC electronic loads are commercially available with DC loads being more prevalent. Either type can emulate a short circuit as well as the CC, CV, CR, and CP modes of operation. According to Adrian Butoi, western regional manager at NH Research, AC loads are used for test applications that require linear or nonlinear AC loading with power and crest-factor control. In addition to the five basic modes of operation, the company’s Model 4600 AC Load also provides unity power-factor loading and a complex nonlinear waveform mode.

Built-in measurements include frequency, voltage, peak voltage, current, peak current, crest factor, apparent power, true power, peak power, reactive power, power factor, and resistance. DC load measurements compose a subset of this list that is not related to reactance.

Cliff Nazelli, the managing director of marketing and sales at PPM Instruments, described a couple of typical applications. In one example, vehicle electrical-system power-distribution module testing must simulate various load conditions. While the module’s durability and temperature rise are monitored, the load current is switched on and off. In another test, fuel-cell impedance is measured by modulating the DC load current. The impedance is determined from the current and voltage amplitudes and their phase relationship.

Isolation also is critical in many cases, especially those that involve off-ground differential voltage sources. Multitap battery load testing is an application that requires this capability.

DC Load Basics

Typically, MOSFETs are used as the dissipating devices in a DC load. These semiconductors have ON resistance much less than 100 mΩ, and several are operated in parallel to achieve the needed power rating. Of course, paralleling devices also reduces the resistance the load presents.

ON resistance is higher for high-voltage MOSFETS than for low-voltage devices, so DC loads rated for 500 V generally will have higher resistance than 50-V loads even if the same number of MOSFETS is used. Figure 1 shows this effect for a 5-kW PPM 600-V load (dark green curve) compared to a 5-kW 60-V load (red curve). The initial slope of the PPM Modular Electronic Load (Mel) 5000-200-600 is 30 mΩ compared to the 1-mΩ resistance of the Mel 5000-600-60 even though there is only a 3:1 ratio relating their maximum currents. The resistances of the lower wattage Chroma loads range from 5 mΩ to 25 mΩ.

Figure 1. Safe Operating Areas for Various DC Loads
Source: Chroma Systems Solutions and PPM Instruments

All electronic loads have a safe operating area (SOA) limited by voltage, current, and power. These areas are indicated in Figure 1 for the PPM Mel 5000-600-60. As the input current increases, the voltage across the load also increases because of the load’s finite resistance. At the maximum current, higher voltages can be supported but only to the maximum voltage and power ratings.

On a graph with linear X- and Y-axis scaling, the maximum power curve is a hyperbola. The load voltage can continue to increase to the maximum voltage limit as long as the current is low enough that the maximum power limit isn’t exceeded. As the figure shows, the SOAs of loads having the same power limit are bounded by the same hyperbolic curve although it may be intersected at different places by the voltage and current limits.

It’s also important to note the lack of standardization regarding load specification in datasheets. The NH Research Model 4750 DC Load and PPM Mel Series show the SOA on a graph with voltage plotted vertically and current horizontally on a log-log grid. Chroma’s 63600 Series datasheet plots this information with the same axes but on a linear grid.

Several manufacturers’ graphs showing low-voltage characteristics generally have linear grids with current plotted vertically and voltage horizontally. Of course, depending on the DUT, current or voltage could be the independent variable, so it really doesn’t matter how the graphs are drawn as long as you understand what they mean.

Finally, model numbers may include power, voltage, and current limits but not always in the same order. PPM’s Mel Series lists power, current, and voltage: Model 5000-200-600 is a 5-kW load with 200-A and 600-V maximum limits. Chroma’s Model 63630-80-60 is a 300-W unit with 80 V and 60-A capabilities.

DC Load Selection

You must choose a load with an SOA sufficient to handle the maximum current, voltage, and power expected from the DUT. The actual combination of current and voltage can lie anywhere within the SOA. Nevertheless, the trend in semiconductors is toward low voltage and high current so supporting this combination often is a major consideration.

Jim Dougherty, senior engineer at Chroma Systems Solutions, explained, “Up to a maximum current limit, a DC load presents a constant minimum resistance. For example, if a load can support a 10-A current and has a 10-mΩ resistance, the DUT output voltage must be at least 100 mV even if the connections and wiring were perfect. Taking into account the finite resistance of the connections and wiring further increases the minimum DUT output voltage required for the load to sink the full current. Of course, the load can be programmed to represent a higher resistance but you cannot get less than the minimum.

“Suppose you have designed and characterized your DUT interconnect and cable resistance and found that RSeries = 2 mΩ. Further, assume you need to support 0.5 V @ 60 A. To do this,” he continued, “the DC load must represent a resistance RLoad <(0.5/60)-0.002 or RLoad <~6 mΩ. The sloping lines in Figure 2 show the resistance associated with three models of Chroma 63600 Series Loads and correspond to the area circled in Figure 1. As expected, the higher the output current rating, the lower the resistance. And, loads can be operated in parallel to achieve higher current capacity as well as lower resistance.”

Figure 2. Low-Voltage Resistance Characteristics of DC Loads
Courtesy of Chroma Systems Solutions

Zero-Volt Operation
What if you need to sink the full rated current but the voltage drop associated with the load resistance and wiring is large compared to the DUT output voltage? Adding a boost supply in series with the load effectively increases the DUT output voltage and makes possible even zero-volt full current loading.

However, Mr. Dougherty cautioned, “Boost supplies should be considered only as a last resort. The effective power of the load that otherwise would be available to the DUT is reduced; you no longer can perform transient tests; noise from the supply affects ripple and noise measurements; and complexity and cost are increased.”

Commenting on his company’s true zero-volt PLZ-4WA Series of DC loads, Takuya Takeda, vice president of Kikusui America, said, “The PLZ-4WA employs a bias supply installed directly in the electronic load. It supports true zero-volt operation by stepping up the input voltage and applying a load voltage adequate to allow the internal current source to operate correctly.

“A switched-mode power supply is small enough to fit inside the load,” he continued. “Typically, a switched-mode supply can create noise issues, but that is not the case with this bias supply. It has been designed using zero-volt switching technology and other special techniques to reduce noise.”

An extensive feature set has developed around the basic DC load function to address a wide range of applications. Four-wire Kelvin connections ensure that the DUT terminal voltage is used in power calculations, not the load voltage that is reduced by wiring and connection IR drops. Also, because many tests require switching the load on and off to stimulate DUT transient response, this aspect of DC load design has become very sophisticated.

Transient Response
A DC load’s internal wiring and terminations must present a low impedance, not just a low resistance. Mr. Nazelli explained that PPM uses a heavy-duty laminated copper bus structure internally in conjunction with a proprietary FET circuit board layout to ensure the lowest possible impedance. In particular, the laminated copper bus minimizes the impedance increase caused by skin effect that otherwise would occur at high frequencies.

The depth at which AC current density has been reduced to 37% of its value at the conductor surface is given by

where: δ = skin effect depth
ρ = conductor resistivity
ω = 2πf
µ = conductor absolute magnetic permeability

For a copper conductor, skin depth varies from more than 8 mm at 60 Hz to only 66 µm at 1 MHz. Engineers have used Litz wire for many years to minimize the resistance increase caused by skin effect. Litz wire is stranded, but each strand also is insulated. A laminated bus achieves a similar result in a form that may be more easily manufactured and terminated, especially for high current levels.

The PPM Mel units are specified with a 15-µs to 20-ms rise time, selectable in 36 discrete steps, and a DC to 10-kHz frequency response. A 600-A load has a maximum slew rate of 600/15 or 40 A/µs. When loads are connected in parallel, the slew rates add. On the other hand, the highest practical slew rate is limited by the inductance of the wiring needed to connect the loads in parallel.

Kikusui’s Model PLZ1004W is a 1-kW load with a maximum current rating of 200 A and a slew rate of 16 A/µs. For the PLZ-4W Series, the slew rate is variable over a 100:1 speed ratio and guaranteed to be accurate to within 10% for current within 2% to 100% of rated value. This series also supports frequency range selection.

According to Kikusui’s Mr. Takeda, “Dynamic response only is required for transient response tests of power supplies. A wide bandwidth isn’t necessary for static tests such as load variation tests and foldback characteristic tests. Excess bandwidth affects load stability so the PLZ-4W/4WA load includes selectable bandwidth, and it can be optimized to match the kind of test and test condition.”

NH Research’s Mr. Butoi explained that because the load manufacturer cannot control DUT and cable inductance, the most straightforward solution to mitigate voltage spikes, ringing, and oscillation is to allow load-current slew-rate programmability. Usually, slowing this slew rate eliminates the problems.

PPM provides two types of filtering as discussed by Mr. Nazelli, “The architecture of the Mel employs a control board with programmable loop response to vary the control-loop speed where you need to adjust rise/fall times for pulse tests and stimulus/response testing. This is one type of filtering. Separately, filtering is used on the FET circuit board assemblies to control the feedback loop response of the power-dissipating devices. The operator can adjust the loops to shape the response either to further control rise/fall times or eliminate oscillations induced from external reactive components.”

Power to the Load

Regardless of the other characteristics a DC load may have, it must dissipate power-sometimes a lot of power. The products in PPM’s Mel Series can handle 1 kW to 5 kW, and master-slave configurations up to 80 kW are standard. Eight models in NH Research’s 4700 Series range in capacity from 1 kW to 36 kW. Chroma’s Series 63200 High Power DC Loads are available in sizes from 2.6 kW to 15.6 kW. These three load series are air-cooled.

Most manufacturers of heavy-duty loads support paralleling for higher power handling. Loads feature individual device protection against over-temperature, over-voltage, and over-current conditions and further ensure performance through active current balancing. For larger power ratings, master-slave systems usually are rack mounted and up to 6 ft high.

One alternative to a big air-cooled unit is a water-cooled unit. AMREL’s PLW Series handles up to 250 kW, and several versions of the 36-kW model are available in a 4U-high x 27.5″ deep rack-mount size. As a comparison, a 5-kW AMREL Series PLA Air-Cooled Load is approximately the same size.

Another solution appropriate for high-power applications is Kikusui’s Model PLZ6000R Regenerative DC Electronic Load. The basic unit acts as a 6-kW load although only about 15% of this is dissipated. The rest of the power is regenerated as a synchronous AC current fed back into the AC mains. Up to five units can be combined in a master-slave system to provide a 30-kW capacity.

Several ranges of benchtop DC loads also are available with ratings to a few hundred watts. Three models from Chroma’s 63600 Series are shown in Figures 1 and 2. B&K Precision’s 150-W Model 8540 handles up to 60 V and 30 A in the CC, CR, and CV modes with current, voltage, and power measurements presented on an integral display. Model 8510 has a 600-W capacity with 120-V and 120-A limits. It, too, provides an integral display and includes a CP mode as well as battery test capability.

Kikusui’s PLZ-4W Series features 165-W, 300-W, 660-W, and 1-kW models. In addition to the basic products, the 165-WA and 660-WA models are available with a built-in bias supply and support true zero-volt operation.

The 300-W Model LD300 DC Load manufactured by Thurlby Thandar Instruments and available in the United States from Saelig has 80-V and 80-A maximum ratings. It supports the CC, CV, CR, and CP modes and provides a transient generator, a variable slew rate, soft start, and a current monitor output.

Controlling the Power
In addition to a load’s fundamental capabilities, the extra features it offers can be important depending on the types of tests you need to run. Kikusui’s PLZ-4W Series includes soft start, a variable slew rate, a switching function, a preset memory function, 100 setup memories, and a sequence function.

B&K Precision’s 8500 Series Loads also support battery testing by measuring total battery discharge in amp-hours. Jeremy Lo, an application engineer at the company, said, “Software is available to control the load for this test. It plots battery discharge curves in real time as well as gives you the option to export raw data in text or Excel format for further analysis. The software also can be used to monitor and plot power, voltage, and current levels at the load inputs.”

In NH Research’s Model 4700 DC Electronic Load, an auto mode provides glitchless switching among the CR, CC, CV, and CP limits. Further, you can programmatically control the mode of operation and its duration via a 100-step customizable macro with 10-µs timing resolution.

PPM’s Mel Loads have several means of control. RS-422 and USB 2.0 ports are standard with both GPIB and Ethernet optionally available. You can log into a load’s IP address to perform remote control and diagnostics. According to Mr. Nazelli, “This also enables PPM to send feature improvements without hardware intervention and without requiring you to return units to PPM. In addition, you can add modules in the field to upgrade a load. The load automatically reconfigures itself to its new capabilities.”

Chroma’s Model 63472 High Slew Rate DC Load incorporates Intel’s power test tool (PTT), which can simulate microprocessor load changes of up to 150 A at a 1,000-A/µs slew rate. Because the PTT is small enough to fit into a microprocessor socket, it cannot dissipate the required power without significantly changing its temperature and operating characteristics. The 63472 provides measurement hardware and over-current and over-voltage protection as well as the automatic calibration required to ensure test-result accuracy.

Unless you use a device such as the PTT, there’s no way to connect a high slew-rate load that will not introduce significant errors. The PTT mimics the load presented by a microprocessor, which may have 100 or more power and ground pins. The slew rate at each pin is only a few amps/µs, and most of the transient current is provided by local capacitors. With the PTT, you are testing the capability of the power supply in combination with local capacitors to cope with the overall 150-A changes and 1,000-A/µs slew rate.

Summary

Many models of DC electronic loads are available, some with very specialized capabilities. Determining the load that will best fit your test requirements starts with a list of the specifications you must have. Power dissipation, maximum current and voltage, and the minimum resistance the load presents are key to most applications. So, too, are the modes in which you will operate the load and how it changes from one to another.

(Source Tom Lecklider –  Evaluation Engineering http://www.evaluationengineering.com/features/2009_september/0909_electronic.aspx )

Megger’s MIT400 Series of Hand-Held 1 kV Insulation Testers

These 1 kV units were designed based on Megger’s extensive knowledge of insulation testing (100+ years of experience) and significant feedback from actual end users.

The MIT400 units include:

Megger’s patented digital/analog display with real-time pointer movement. Other manufacturer’s units do not offer a true analog arc display with pointer travel. Some offer only a digital readout while others offer an analog bargraph that does not provide any of the information gained from pointer travel.

Industry best (by far) measurement sensitivity, allowing users to identify potential problems early before they become bigger problems. The MIT400 Series’ measurement sensitivity (up to 200 GΩ) dwarfs anything found on comparable units.

CAT IV, 600 V safety rating on BOTH insulation and continuity  measurement ranges. Some competitive units claim a CAT IV, 600 V safety rating, but have no rating on the continuity measurement.

Industry best IP54 (ingress protection) rating (protection against splashing water from any direction). Some competitive units have an IP rating of IP40, which means they are not protected against liquid ingress at all.

How important is the electrical equipment you intend to test?

The MIT400 Series offers the highest measurement range available, which will allow you to identify problems early. Additionally, the real-time analog arc provides an experienced user key additional information.

In what types of environments are you testing?

The MIT400 Series has the highest IP rating of the available instruments. They can be used effectively in the harshest conditions.

How important is safety?

In addition to being CAT IV, 600V rated, the MIT400 Series units (like all Megger insulation testers) are designed with Megger’s Intelligent Safety System, which includes specific protection circuitry to ensure that, in the case of incorrect connection or accidental connection to unsuitable circuits, no damage will occur to the instrument, and the operator is fully protected.

Do you want to purchase a true insulation tester?

All Megger models are based on an insulation tester “footprint” and are designed for insulation testing applications. Some competitive units are multimeters first with insulation testing capability added second.

Application Guru, Jeff Jowett of Megger answers the following question.

Q:  What is the significance of line powered or battery powered?

A: Battery power is safe and more convenient. But in the “old days,” batteries developed a bad reputation for unreliability and rapid drain. Modern conservation techniques in well-designed equipment have eliminated these shortcomings, making battery-powered units more portable and, of course, not dependent on site power, hence more amenable to field work and construction environments. They also provide a much better regulated power source, free from the effects of transients and other line disturbances. Furthermore, as a self-contained power source, they can be designed so as to be well within safety parameters, which is difficult to guarantee with line power that is connected to the North American grid! A common misconception is that line power somehow provides a “better” (i.e. more robust) test. The only thing that all that extra power might get you is arc flash! It does NOT provide a more reliable test.

The only disadvantage that batteries do have is that they eventually go dead. This leaves battery power open to “human error.” Dual-powered units, both line and battery operated, therefore offer the best of all worlds. To paraphrase a former light heavyweight champion, Tommy Loughran, “Use batter power when you can, line power when you must.”