1672/1673 FC/1674 FC
Users Manual
40
RCD Trip Time Measurement
In this test, a calibrated fault current is induced into the circuit to cause the RCD to trip. The
Tester measures and shows the time required for the RCD to trip. You can do this test with test
leads or the mains cord. The test is done on a live circuit.
You can use the Tester to do the RCD tripping time test in Auto Start and make it easier for one
person to do the test. If the RCD has a special nominal current setting other than the standard
options, 10, 30, 100, 300, and 500, or 1000 mA, you can use a custom setting with the Var
mode.
This test is done on a live circuit. If no voltage is detected, the Tester inhibits the test and this
message shows on the display:
W No voltage detected. Cannot start test.
Note
When you make trip time measurements for any type of RCD, the Tester first
determines if the actual test will cause a fault voltage exceeding the limit (25 V or 50 V)
and shows a warning message on the display.
To avoid an inaccurate trip time for S type (time delay) RCDs, a 30-second delay is
activated between the pretest and the actual test. This RCD type needs a delay
because it contains RC circuits that are required to settle before applying the full test.
RCD type B, B+ or S-type B, B+ are actually two RCDs, one with type A/AC behavior and one
with type B. The type B RCD is correctly tested only with the trip current (ramp) test. For trip
time measurements, even with type B selected, the ac part of the RCD might cause the tripping
because of the initial step of the test current. Fluke recommends that you do a trip current test
with type B and a test with type A/AC waveform.
XW Warning
To prevent possible electrical shock, fire, or personal injury:
Test the connection between the N-conductor and earth before you start the test.
A voltage between the N-conductor and earth may influence the test.
Leakage currents in the circuit that follow the residual current protection device
may influence measurements.
The displayed fault voltage relates to the rated residual current of the RCD.
Potential fields of other earthing installations may influence the measurement.
Equipment (motors, capacitors) connected downstream of the RCD may cause
considerable extension of the tripping time.
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