The Chroma Guardian 19050 series of Hipot Testers are comprised of three models. The Guardian 19052 is equipped for AC/DC/IR Hipot testing and insulation resistance (IR) measurements. The Guardian 19053 combines both AC and DC Hipot tests and IR measurements with 8HV scan channel capabilities. The Guardian 19054 combines both AC and DC Hipot tests and IR measurements with 4HV scan channel capabilities.
The O.S.C function is used to check whether the connection is open, or a short circuit, between the instrument and DUT (device under test) before the Electrical Safety Test is performed. If the connection is bad between the instrument and DUT, like bad leads or relay oxidation, the test may result in a PASS determination. In some cases, the DUT has a short before testing. Testing continually leads to instrumentation damage due to it suffering the high load current. Therefore, we check for the open and short circuit to ensure the test is effective and to protect the instruments.
Generally, DUT have a capacitive load (Cx) from tens to thousands of pF. If the connection is open, a capacitance will appear and then total capacitive load is lower than that of normal conditions. If the DUT is shorting, the total capacitive load is higher than that of normal conditions. Therefore, we can measure the value of the capacitive load to verify whether the contact is good or not.
Flashover Detection (ARC)
Fast transients in voltage or current during hipot testing are called electrical flashover. Normally, with AC line frequency (50Hz/60Hz) or DC hipot testing, the leakage current is the same 50Hz/60Hz or DC (charge current excepted).
In contrast, when electrical discharge occurs due to poor insulation materials, electrode gaps, surface clearances, etc., fast transients in leakage current become apparent. Most of the electrical safety regulations state a necessity of withstand strength test. Nevertheless, general hipot testers only detect the RMS value of leakage current without the capability to detect flashover. Therefore, a hipot tester equipped with FLASHOVER detection function is necessary.
Ground Fault Interrupt (GFI)
A requirement for test environments indicates that test equipment be equipped with an auto interrupt device. Chroma builds in a Ground Fault Interrupt (GFI) function for this purpose. When the current meter A1 and A2 detect a difference (i2-i1=iH) between the value i1 and actual i2 test current over high, this device can cut the power transiently to protect the operator. It is not only compliant with the safety standard but also provides additional safeguards for the test personnel.