Atec Megger-830280 - Manual (Page 2)

One-Winding
Measurement
Transformer Ohmmeter
Transformer Winding Resistance
and Tap-Changer Test Set
Tap-changers are mechanical devices and the most
vulnerable part of a transformer. Tap-changers result in
more failures and outages than any other component and
so require frequent testing and attention to ensure proper,
reliable operation.
The Transformer Ohmmeter can be used to check the
make-before-break operation of on-load tap-changers and
also to measure the contact resistance of each tap position.
FEATURES AND BENEFITS
■ Direct digital reading saves time, no balancing is
required.
■ Built-in discharge circuit safely discharges the specimen
when test is completed, if lead accidentally disconnects
or if power is lost.
■ Electromechanical safety indicator gives a visual
indication of a charged or discharged specimen, even if
power to the instrument is lost.
■ Two independent measuring channels allow
simultaneous testing of primary and secondary windings
or measurement of two phases at a time.
■ The sensitive surge detection circuitry monitors the
contact operation of on-load tap-changers for the proper
make-before-break sequence. If an open circuit
condition exists, the instrument shuts down immediately.
■ High-accuracy, four-terminal bridge: no lead
compensation required.
■ Electronically generated and regulated current supply
overcomes high-inductance transformers quickly,
allowing fast measurements to be taken. Display of
measurement occurs only after test current stabilizes.
■ Wide resistance range allows heat-run testing of many
transformer types.
■ Lightweight and portable, the Transformer Ohmmeter is
ideal for use in shop or substation environments.
■ Overtemperature protection provides automatic current
shutdown and LED indication to prevent instrument
damage.
■ Instrument and accessories come in a foam-lined
transport case.
Schematic comparison of
one- and two-winding
measurements
Low-Voltage
Winding
High-Voltage
Winding
Simultaneous
Two-Winding
Measurement