Safety Testing / Surge Testing

There are a variety of Electrical Safety Testing and Surge Testing Equipment available that enables the user or manufacturer to test the integrity of electrical insulation, electrical isolation, component specifications, cable / connection bonding or electrical isolation. These instruments are commonly used to verify the specifications of a manufactured product as well as confirm the safety for the user, installer and operator of an installed or repaired system. Tests are typically performed on wire, cable, motor windings, switchgear, insulators, components, incoming service, transformers and any electrical device that must meet safety standards.
Typical industries required to test according to safety standards:

Hipot Testers, Ground Bond Testers, Leakage Current Testers or Impulse/Surge Testers are required tests for product and system evaluation and are accepted tests in order to meet Industry Electrical and Safety Standards.

Hipot Testers (High Voltage Testers aka Dielectric Tester)

• AC Hipot Test
• DC Hipot Test

• Since a DC Hipot applies exactly the recommended voltage and does not cycle between positive and negative peak voltages, it is effective regardless of the product or system capacitance.
• In highly capacitive circuits, DC testing will charge the capacitor where it might trip with an AC tester and not be possible to test at all.
• In order to protect the system, "Y" capacitors are frequently used by instrument/appliance manufactures to protect DC electronics. They protect controls and computers against high frequency surges and RF noise in the AC line by shunting noise to ground. An AC Hipot that normally charges from positive voltage to zero and then negative voltage will have a harder time providing the test with Y capacitors in the ciurcuit, than a DC Hipot.

• The current trip for the leakage may be set on a significantly lower value. The manufacturer may then identify and remove products with marginal insulation that may have otherwise passed.

• Only one direction of polarity can be tested with DC
• Not all test standards consider DC testing to be on the same par as AC testing. While most standards allow either, testing of large motors is still by AC Hipots. There are some very old legacy standards that predate the availability of DC Hipots
• Unlike its AC counterpart, the DC Hipot test cannot replace the test for line voltage leakage

• AC testing checks both polarities of voltage. Products that use AC for normal operation should not be tested by a DC Hipot
• Information with an AC Hipot is instantaneous. DC Hipot testers require a few seconds at the end of each test to discharge the internal capacitor. Although not normally a problem, it may be a consideration when testing time is of the essence, as in a production line
• AC testing is accepted by all test standards

• Since an AC source for testing produces a peak positive and negative signal, highly capacitive circuits may reduce the accuracy and timing of the test and interfere with leakage and tripping current. (see first bullet for DC Hipot Advantages)
• Since AC testing actually applies a peak positive voltage as well as a peak negative voltage and then cycles between each, the current produced during testing is greater and may actually weaken the insulation being tested. This in turn may cause failure of the product either in normal use. We welcome your comments on your experience.

Ground Bond Test or Earth Bond Test (High Current Test) Testers

• Perform protective continuity testing in Compliance with International Safety Standards
• Protective continuity resistance measurement for medical devices and general electrical devices
• Ground connectivity testing when installing electrical machine tools and distribution panels
• Test protective grounding and electrostatic fields such as grounding work for medical equipment
• Evaluate contact status using large currents
• Feedback control system capable of applying a stable current, even with a fluctuating load
• Provide a soft-start function which confirms the connection to the device under test before applying current

• Test Sequence Memory Capability
• Ground Bond Test Capability
• Broadband Arc Detection
• 4-Wire Milli-Ohmmeter Function
• Secure Level of Operator Safety
• High Power Output
• Wide Range of Voltage Capabilities
• Built-in Phase Angle Measurement for AC Signals
• Ramp High / Dwell Low Current Limits
• Test Report capability
• Ethernet and GPIB Pico-Amp Leakage Measurement
• Cable Compensation Multi-Mode IR Test Capability
• Continuously Variable IR Test Voltage Capability

• Telecom Engineers
• Power Systems Engineers
• Electricians
• Electrical contractors
• Medical Test Engineers
• Consulting Engineers

Leakage Current Testers

• Medical
• Industrial
• Residential
• Consumer Electronics
• Service
• Laboratory
• Production

• General Industrial Electrical Use
• Medical Standard Equipment
• Medical Emergency Equipment
• Computers
• Residential Appliances
• Electrical Toys and Monitors

• As a class, they are an economical tester to comply with standards governing electrical devices
• Capability for required standards IEC, JIS, UL, DIN VDE, ANSI, etc.
• Selectable test current
• Polarity switching reduces cycle time
• Rated currents to meet new Standards
• Touch panel for interactive operation.
• Complete communications functionality
• External I/O Support
• Automatic testing for production line applications
• Memory storage of programmed tests
• Memory storage of test results
• Report function capability
• Measure housing leakage current
• Single phase or three phase capability
• Capable of 120VAC or 240 VAC appliance testing
  

Impulse /Surge Testers

Impulse Generators originated from the need to test electrical equipment and surge arrestors by simulating the high voltage and current of lightning and other surges. Modern day impulse generators originate from the work of Edwin Marx in the 1920’s. You may see “Marx Generator” or “Marx Circuit” in manufacturer literature. There are two types

• Impulse Voltage Generators . High voltage pulse is generated by charging multiple capacitors in parallel then discharging in series.
• Impulse Current Generators. High current pulse is generated by charging multiple capacitors in parallel then discharged in parallel.

Medical Device Safety Testers

Electrical Safety Test Methods for Equipment