6
MTO106
ZP-BN01E
BN034794AE
1 INTRODucTION
1
I
ntroduction
1.1 Product description
The MTO106 transformer ohmmeter is an easy-to-use,
line-operated instrument specifically designed for safe
and accurate field measurement of winding resistance
in smaller transmission and distribution transformers.
It has dual channels with a wide measurement range
and can accurately provide information about the
vast majority of power transformers, reactors and
instrument transformers. The test current can be
manually set in five different ranges to fit transformers
of various sizes.
The unit has built-in safety protection for testing
transformers and other components with high
inductance. To ensure operator safety, MTO 106
automatically discharges the stored energy in the
transformer at the end of each test. If a current lead
is disconnected while current is flowing through
the transformer, the current will flow through the
alternate path of the potential lead without damage
to the instrument or risk to the operator
Features and benefits
▪
Test current up to 6 A and stable current generation
▪
up to 48 V output voltage for fast charging of
transformer windings
▪
Light weight and portable
▪
Very short start-up time
▪
Ease of use
▪
Resistance range, 10 µOhm to 30 kOhm, for testing a
wide variety of transformers.
Applications
The MTO106 is mainly intended for field
measurements of smaller transmission and distribution
transformers:
▪
To verify factory test readings
▪
As part of a regular maintenance program.
▪
To help locate the presence of defects in transformers
such as increased contact resistance in terminal
connections and tap changers.
The instrument can also be used for general resistance
measurements of for instance control wiring, voltage
regulators, motors, generators and all types of
connections.
1.2 Winding resistance
testing
Transformer winding resistances are measured in
the field in order to check for abnormalities due to
loose connections, broken strands, and high-contact
resistance in tap changers. Interpretation of results is
usually based on a comparison of measurements
made separately on each phase in the case of a
wye-connected winding or between pairs of terminals
on a delta-connected winding. comparison may also
be made with original data measured in the factory.
Winding resistance measurements in transformers
are of fundamental importance for the following
purposes:
▪
calculations of the I
2
R component of conductor losses.
▪
calculation of winding temperature at the end of a
temperature test cycle.
▪
As a diagnostic tool for assessing possible damage in the
field.
Problems or faults occur due to poor design, assembly,
handing, poor environments, overloading or poor
maintenance. Measuring the resistance of the
windings assures that the connections are correct and
the resistance measurements indicate that there are
no severe mismatches or opens. Many transformers
have taps built into them. These taps allow ratio to be
increased or decreased by. Any of the ratio changes
involve a mechanical movement of a contact from one
position to another. To tetect contact wear, winding
resistance measurements are usually performed at
each tap in a load tap changer.
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