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Application
3.5 TRTapCheck Test Card
Use the TRTapCheck test card to measure the winding resistance of the
individual taps of a power transformer’s tap changer, and to check whether the
on-load tap changer (OLTC) switches without interruption.
The CPC 100 injects a constant current from the 6 A DC output into the power
transformer and the current is led via the IAC/DC input for measurement. From
this current value and the voltage measured by the V DC input, the winding
resistance is calculated.
The moment the tap is changed, the IAC/DC measuring input detects the
sudden, very short drop of the current flow. A properly working tap change
differs from a malfunctioning one, for example, an interruption during the
change, by the magnitude of the ripple and slope values. An interruption will
result in much higher ripple and slope values than a properly functioning tap
change.
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General