CPC 100
V 3.20
Transformer - 6
Transformer
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
6A DC
output into the power
transformer and the current is led via the
I AC / DC
input for measurement.
Alternatively, the current injected from the
400A DC
output is measured internally.
From this current value and the voltage
measured by the
V DC
input, the winding
resistance is calculated.
In the moment the tap is changed, the
I AC / DC
measuring input detects the
sudden, very short drop of the current flow.
A properly working tap change differs from
a malfunctioning one, e.g., 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.
The ripple and slope values are indicated at
the
TRTapCheck
test card’s measurement
table.
taps
OLTC
DANGER
Death or severe injury caused by high voltage or current
►
Never open the measuring circuit while current flows.
►
After a measurement, wait until the discharge procedure is completed.
►
If you have to change the wiring after a test, use a grounding or discharging rod.
CP SA1
Note:
It is
recommended
to use the
CP SA1
for
this test.
Actual test
current
Nominal test
current
Measured voltage
at
V DC
input
Output range
Winding connection
Reference temperature
Actual specimen
temperature
Tolerance of the
deviation in %
Settling time
Automated tap
operation
Rmeas: Actual resistance
Dev.:
Deviation in % between the maximum and the minimum measured values evaluated with
the settling time.
R ref.:
Temperature-corrected resistance value
Ripple:
Samples and holds the biggest measured current ripple that occurred in the measuring
cycle. It is indicated in % with reference to I DC.
Slope
Samples and holds the biggest measured steepness of the falling edge of the actual test
current.
Transformer tap
identifier and tap
number
TRTapCheck (for OLTC)
