An Introduction to Dielectric Withstand Testing with the HT-5000 The dielectric withstand test is a test which is recognized by safety agencies worldwide as a valid criterion of safe assembly of end-use equipment. The HT-5000 is designed as a research instrument to determine the dielectric properties of component assemblies of end-use equipment. It applies a high-voltage potential between Output and Return test leads and monitors Leakage Current and watches for Dielectric Breakdown during the test. To aid in testing, the HT-5000 can be configured with or without voltage ramp time, with or without a test duration timer, and can be set to deliver high voltage after an arc has been detected to allow safety engineers to pinpoint the problem. The dielectric withstand test involves high voltage and caution should be exercised when using the HT-5000. The Return Jack on the front panel is connected to ground potential, and setups should be designed with this in mind, to guard against the operator contacting high voltage. Always make sure the return lead is firmly connected. Leakage Test The HT-5000 leakage test uses a separate low-frequency circuit to detect excessive current as a result of low impedance between the Output and Return jacks on the front panel. There is not a specific leakage current level pass/fail requirement at this time for most equipment. However, higher than normal leakage current on a particular sample may indicate an assembly or component problem in the circuit. The leakage current is also monitored by the HT-5000 to ensure that excessive leakage does not keep the Tester from developing full voltage required for the high voltage test. The HT-5000 will provide full voltage at any leakage current level up to 10 mA AC and 5 mA DC. The leakage current trip level is adjustable on the rear panel. If the green Full Voltage LED lights and the test continues, the leakage current was below the amount set by the rear panel adjustment. If the red Excess Leakage LED lights, the buzzer sounds, and the test is terminated, the leakage current was over the amount set by the rear panel adjustment. High Voltage Dielectric Withstand Test This test checks for insulation system breakdowns by applying a high voltage between the Output and Return jacks on the front panel. The HT-5000 uses a separate high-frequency circuit to detect arc breakdowns of greater than 100 nsec duration. The duration of the test is controlled by the test time control on the back panel. The test time is counted from the time the Full Voltage LED is lit to the completion of the test. The timer may be defeated, allowing the test to continue for as long as the TEST Button is pressed. The minimum test time when the timer is defeated is one second. If the green Hipot Pass LED lights, the test cycle has been successfully completed, meaning there was no dielectric breakdown, If the red Hipot Fail LED lights, a breakdown arc has been detected.