Special Report: Electrical safety test vendors packing value-adds into solutions

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As various applications see demands rise for power usage, power density, and efficiency, the need to test for electrical safety goes hand-in-hand. Software continues to play a growing role in helping automate these tests, while vendors of instrumentation in this field are challenged to keep up current industry standards, and design with future standards in mind. Hipot, insulation-resistance (IR), ground-resistance, and ground-bond (GB) testing are all critical elements of measuring electrical safety across various industries. Thankfully, technology has enabled electrical product safety test instruments user-friendly—increasingly leaving it up to the user’s interpretation or “gut” feeling. Guess-work is an enemy of product safety testing, after all.

“Today’s electrical safety testers are far easier to use than ever before,” Vitrek founder and application specialist Kevin Clark told Evaluation Engineering. “This advancement has been made possible by the use of color touch displays that take the guesswork out of operating a complex multifunction safety analyzer. A touchscreen, graphical user interface walks the user through test set-up, recall and operation—both speeding up the process and simplifying it.”

Clark added that while these digital features continue to expand in electrical safety test instrumentation, one doesn’t have to buy a large, expensive system to take advantage of these user-friendly capabilities. For example, Vitrek’s V7X series of compact, benchtop safety testers are built around touchscreen technology, with four of the company’s six models priced at under $2,000.

Vitrek has plenty more options to back that up. The Poway, CA-based company offers 14 different models of electrical safety testers to handle a wide variety of testing applications. The aforementioned V7X series consists of six models with AC/DC hipot and IR testing up to 5KV and GB testing up to 30 amps. The V7x series meets the safety test requirements for the vast majority of the of product categories, including most appliances, power supplies, and electrical components. For more demanding application requiring more output power, higher measurement resolution, greater GB test current and hipot voltages up to 30KV, Vitrek’s 95X series of electrical safety compliance analyzers provides an ideal solution.

“One of the most unique capabilities of Vitrek electrical safety testers is the ability to control up to four of the Vitrek model 964i high voltage and high-current scanning systems,” Clark added. “Each 964i HV scanning system holds up to 64 relays with switching modules rated at 3, 7, 10, or 15KV and current switching up to 70 amps. The combination of a Vitrek safety tester and switching systems permits test engineers to tackle tough multipoint hipot applications like cable harnesses, medical devices, multi-conductor cables, and electric vehicle systems and components.”

Trends & challenges

We at EE gathered commentary from a handful of vendors regarding what they see as current trends in the area of electrical product safety testing, as well as ongoing challenges. Here’s what they had to say.

Dan Carter, EST/LCR product manager at Chroma Systems Solutions: “We are seeing more and more demand for traceability in the form of different communication interfaces and the use of data recording software. Many customers are looking for ways to centrally store test data in companywide databases. Our instrument control software packages allow for integration into SQL databases. Vendor challenges: Every customer’s requirements vary and it’s important to cover all bases when specifying equipment for these varying requirements. It can often be difficult to get all of the necessary information from customers in order to correctly identify the perfect piece of equipment for the job. Customer challenges: Standards change and are often interpreted in different ways. This can lead to confusion when trying to be compliant.”

Ronit Mukerji, portable and benchtop test instruments product manager for Yokogawa: “A key challenge for vendors whose core product line does not revolve around insulation testers is to satisfy the higher-end applications and end users. These applications would require being able to output into the kV range, or measure into the sub micro-ohms. As such, these types of testers would be considerably more expensive to manufacture. Mid- to low-range applications would require less resistance measurement resolution, as well as lower test voltages. For customers, a key challenge would involve determining exactly which type of tests to perform to properly and adequately characterize insulation. Industry standards such as polarization index and dielectric absorption ratio are usually the go-to, as they provide a quantifiable value for insulation quality. However, they are not useful for checking long-term insulation degradation. Other tests, such as time resistance testing, are more suited for the above application.”

Katherine Homan, president of Cortek Test Solutions: “Standards change and are interpreted differently by both vendors and customers.”

Compliance

Essentially every electronic device or piece of equipment must undergo rigorous electrical safety testing and pass certification before it can be marketed, and the requirements for certification are largely dependent upon many safety standards—which vary by global region. The most prominent organizations setting these standards include: EN/IEC (Europe); UL (US); JEIDA/MITI (Japan); CCC (China); and CSA (Canada).

Some standards between these agencies conflict with each other, and things can quickly become confusing when a vendor from one region sells to a client from another. But, as Vitrek’s Clark noted in a whitepaper he authored for his company published this past November, there is an ongoing effort between these agencies to harmonize standards.[1]

“For example, the IEC 61800-5-1 is a safety standard specified by the International Electrotechnical Commission for adjustable-speed electrical power drive systems,” Clark said in the whitepaper. “It covers the safety aspects related to electrical, thermal, and energy. The former UL standard (UL508C) has now been supplanted by new standard, harmonized with the IEC requirements.”

The UL document announcing the IEC 61800-5-1 change stated, “This harmonization work was undertaken with the intent of creating a standard that, while being based upon and adopting IEC requirements, would incorporate national differences that would address US installation requirements (NFPA 70, US National Electrical Code). This goal has largely been accomplished in all cases.”

On a more local scale, vendors themselves are helping play a large role in helping electrical device manufacturers remain aware and meet safety standards. It’s a service area these vendors can use as a value-add beyond their product offering, and to set themselves apart in the market.

“Vitrek’s application engineering team has years of experience and has assisted thousands of engineers in solving difficult electrical safety compliance test requirements,” Clark said. “We are experts at understanding test specifications and implementing the appropriate automated solution. Often, nationally recognized testing laboratories require that operators perform a daily external verification check to ensure that a safety tester is functioning properly. Vitrek’s application team can provide standard operating procedures for performing these checks with either an off-the-shelf performance verification device (PVD) or design a custom PVD designed around the specification that the user is testing to.”

Chroma’s Carter added that his company helps customers achieve compliance by reviewing their requirements with them and providing solutions based on a combination of their standards-based requirements and wish-list items based on their unique situation.

Now on the market

Vendors of electrical product safety testing will show off their latest and greatest innovations at upcoming industry events such as the Dixie Crow Symposium (March 24-27 in Warner Robins, GA), the Del Mar Electronics & Manufacturing Show (May 1-2 in San Diego, CA), the Medical Device Innovation Program (May 7-8 in Boston, MA), and the Battery Show (September 10-12 in Novi, MI). Let’s take a look at some of what will be showcased there, or in general as new offerings:

Kikusui has recently introduced its TOS9300 Series, which is a high-performance electrical safety analyzer that enables the user to perform electrical safety tests compliant with a wide range of universal standards. It covers hipot, insulation-resistance, ground-bond, leakage current (touch current and protective conductor current), and partial discharge test. The multifunctional tester increases productivity and saves valuable space on the production. It is ideal for research and development, quality assurance, production line, and laboratory applications. The TOS9300 includes a special mechanical structure to lock the LOW test lead terminal for safety, as well as a stress-free terminal structure for test leads. The TOS9300 has an interlock function, an automatic discharge function after the test, a remote control option, and double-action or momentary operation.

Carter, Chroma: “Chroma offers a wide variety of electrical safety testing equipment, from basic benchtop hipot testers, to all-in-one test solutions like our 19032 Electrical Safety Analyzer that combines hipot, IR, GB, leakage current (LC)/AC, LC/DC, LC, and dynamic function tests in one unit. What sets Chroma apart is our complete line of automated test systems for electrical safety. Our Sentinel systems combined with our CaptivATE software platform provide medical device and other manufacturer’s automated efficiency with increased throughput. We go well beyond conventional hipot testing in our electrical safety testing line. We have partial discharge testers for use with lithium-ion batteries and semiconductors (Models 11210 and 19501). We have surge testers that also perform hipot and DCR (19036), and we can build automated test solutions complete with training and software to cover all of our customers’ test requirements.”

Homan, Cortek: “Cortek provides both off-the-shelf as well as custom hipot safety enclosures and bed-of-nails functional test fixtures with safety guarding or covers. These units connect directly to hipot testers or integrate to more elegant electrical safety test systems for ATE. They are designed to reduce the hazard of high voltage discharge and safeguards operators from the dangers associated with high voltage testing. When used properly, the safety enclosures and test fixtures can prevent injury from high voltage electric discharge and damage to the devices being tested. Key differentiators with our products are they are scalable—we can shrink and grow many of our products in the X/Y/Z axis with relative ease and cost. This sets us apart from the competition and allows the customer to purchase a safety enclosure to fit their requirement.”

Mukerji, Yokogawa: “Yokogawa’s offerings in this area include:

Insulation testers—MY600 Digital Insulation Tester; 2406E Series Analog Insulation Tester, which covers 10 voltage and resistance test ranges
Clamp-on testers—CL Series Clamp-On Testers that span AC/DC/True RMS current and voltage measurement capabilities
3003 Series Leakage Testers
EY200 Earth Ground Tester

Product application options

Besides providing testing instruments, vendors are increasingly adding new options that are particularly applicable for electrical safety test, such as software or probing solutions. Here are some examples.

Clark, Vitrek: “Vitrek offers a wide variety of options to facilitate safe and easy connection of the tester to the DUT. For corded products, we have a TL-UP series of universal power receptacle test adaptors that accept all of the world’s major power plugs. This test adaptor is available in three configurations—hipot & GB, hipot-only, and GB-only. We also offer the same functionality in an IEC 320 style and North American (NEMA 5-15) style receptacle. Vitrek’s QuickTest Pro software turns a stand-alone hipot tester into a PC-based automated test system with comprehensive data acquisition and storage. An easy-to-use graphical interface allows users to choose from hundreds of test sequences and use a bar code reader to scan DUT serial number data and initiate the test. Test results with pass/fail status, readings, time, date, and operator are all automatically stored by DUT serial number for tracking purposes.”

Carter, Chroma: “Our CaptivATE software is designed for use with our electrical safety testing equipment. CaptivATE allows our customers to create and store test files, control the test equipment, automatically call up test profiles based on the DUT’s bar code, export the data to a centralized location, and more. All with automation, efficiency, and traceability in mind. We also offer our customers safety enclosures and fixtures for the many unique device-under-test applications.”

Homan, Cortek: “In addition to the enclosure itself, options available from Cortek are safety light trees, start/stop switch, E-stop, insulation mats, and specialty materials such as red UV acrylic to temper any bright lights during the safety test.”

Mukerji, Yokogawa: “Our MY600 comes with a line probe that allows the user to disconnect the UUT from the insulation tester at-will; automatic PI/DAR calculations; pass/fail color Indicators for comparative testing; software to stream data collected from the unit to a PC via USB; and a fast response time of 0.5 seconds.”

Operator safety

While the aim of electrical product safety testing is to evaluate the safety of the product itself, the equipment doing the testing must also ensure the safety of its operator—particularly when performing high-voltage tests. What features do vendors offer that aid user safety?

Carter, Chroma: “All of our electrical safety testing equipment comes standard with a safety interlock. Our hipot testers also have a GFI feature that will shut down the output in the case that there is current escaping to ground during a test. We can also provide custom fixtures and enclosures that can help create a safe test environment.”

Homan, Cortek: “Cortek has been developing and manufacturing custom functional test fixtures for more than 25 years, utilizing traditional spring contact probe technology to make electrical contact to the unit under test. Test fixtures for high voltage and/or high current applications require safety guarding and interlock switches to prevent electrical shock to the operators performing the tests. Our high-voltage enclosures come standard with a magnetic safety interlock switch and chassis ground wire connection that must be hooked up by the customer.”

Mukerji, Yokogawa: “Features of our MY600 include a backlight LED that automatically illuminates in dark surroundings; a line probe with an adjustable switch to disconnect the measurement circuit from the UUT; an intermittent buzzer that warns of the high voltage output range; and a ground fault indicator and buzzer once the earth-ground voltage exceeds 30V.”