Guardian Hipot Tester AC/DC/IR/SCAN

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 reult in a PASS determination. In some cases, the DUT has a short before testing. Testing continually leads to instrumentation damage due 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 capactive load to verify that the contact is good or not.

All of the 19050 series testers have a ground continuity check feature to determine the resistance between the ground blade of the power cord and any exposed metal on the product. This resistance should be less than 1Ω.

A requirement for test environments indicates that test equipment be equipped with 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 for protection of the operator. It is not only compliant with the safety standard but also provides additional safeguards for test personnel.