Omicron CPC 100 User Manual

CPC 100 V 3.20
Transformer - 7
Tap Changer Test and Measuring the Winding Resistance
When testing a tap changer, we recommend the following:
► Inject the same current value for each phase.
► To perform tests of each phase, start with the lowest tap through to the highest and continue
backwards down to the lowest tap again. Taps may show quite different results depending
on the direction of the tap movement and defects can behave differently. An interruption
caused by a defective tap changer results in comparatively high measured values for ripple
and slope.
Example: Results of a tap changer and winding resistance test
For the tap changer test, the last two columns of the table are relevant.
Note: If the CPC 100 is in Auto Keep Result status, the user can end the process by either
pressing Keep Result or by changing to the Tolerance setting and changing the value. The soft
key Set Current Deviation resumes the value of the current deviation in the Tolerance field.
Performing a Tap Changer Test
This test is identical to the voltage withstand test described on page Current Transformer-4.
High ripple because inductance is
charged
Values okay because always in the
same range
Tap defective: significantly higher values for ripple and slope. Compared to the properly functioning
tap change of line 5, for the defective tap in line 7 the ripple is about 30 times and the slope about 15
times higher.
After pressing the Auto Keep Result menu key, the CPC 100 waits until stable
results with a deviation less than the defined tolerance (in %) within the defined
settling time ( t) are achieved. After then, a new result line is added and the next
measurement starts.
1. Press the I /O (test start /stop) push-button to start the test.
2. Press Keep Result to save the resistance value of this tap or press Auto Keep
Result. In this case, the CPC 100 waits until stable results within the set
Tolerance and t are achieved. After then, a new result line is added showing
the number of the next measured tap.
3. Move to the next position on the tap changer.
4. Repeat steps 2 and 3 for all taps you want to measure.
5. Press the I /O (test start /stop) push-button to stop the test and wait until the
transformer windings are discharged.
DANGER
Death or severe injury caused by high voltage or current
► Before disconnecting the transformer under test, ground all transformer
connections.
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TRTapCheck (for OLTC) Voltage Withstand Test

Omicron CPC 100 Specifications

General

Brand	Omicron
Model	CPC 100
Category	Test Equipment
Language	English