Specifications

High DC current reslstance meter
Micro OhmMeter
P.54
DV-POWER
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Wardson Limited
Unit A & B, 21/F., Infotech Centre, No. 21 Hung To Road Kwun Tong, Kowloon, Hong Kong. Web: www.wardsonlimited.com
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High DC current reslstance meter
Micro OhmMeter
Using RMO10T's TapChanger menu, the power
transformer winding resistance of individual tap
positions can be measured. Also, you can check
whether the on-load tap changer switches
without an interruption. The RMO10T current
output injects a constant current into a power
transformer. This current and voltage value is
measured, and the winding resistance is
calculated.
Testing of a Delta-delta winding resistance is
usually a very time consuming procedure. This
is because the two windings represent two
closed loop inductors. When energy is brought
into the inductors, this energy (in the form of
D.C. current) continually circulates within each
winding. To test this configuration quickly, both
high and low sides should be connected in
series with the current source of a Transformer
Ohmmeter. By having these two windings in
opposing polarity, the internal circulating
currents settle very quickly to obtain a balance,
and discharge with the same speed. Even if
only one side of the transformer needs to be
tested, connecting both high and low windings
in series will speed up the test considerably.
The RMO10T should be turned off, connection
between RMO10T and the test object is such
that the measuring cables from the "Voltage
Sense" sockets are attached as close as
possible to the measured resistance, while
they are connected between the current feeding
cables. That way, resistance of cables and
clamps is almost completely excluded from the
resistance measured . The figure to the right
shows simultaneous testing of both windings
(high and low) on a single-phase transformer.
In such a way, it is possible to speed up the
measurement when two channels are used to
test both windings of the transformer.
Connecting a Test Object to RMO10T