Megger MOM2, User Manual

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8 MOM2 ZP-BD03E BD0333FE
2 INTRODUCTION
2
I
ntroduction
The MOM2 is designed to measure the resistance of
circuit breaker contacts, bus-bar joints, contact ele-
ments in bus-bars and other high-current links.
When contact resistance rises because of oxidation,
loosened or improperly tightened threaded joints,
temperatures rise abnormally at the points of contact.
This abnormal heating reduces conductivity thereby
accelerating the rise in temperature — and this often
leads to serious trouble.
The MOM2 micro-ohmmeter can be used to detect
such problems early so that they can be remedied
long before trouble starts. Checking contact resistance
at regular intervals provides a clear indication of the
state of your system.
2.1 Basic technical
description
The output current is delivered from a supercapacitor
which is charged from the built-in rechargeable bat-
teries.
Kelvin test
The MOM2 uses Kelvin probes or clamps for the
measurement. A Kelvin test uses four wires and meas-
ures continuity resistances ensuring all contact and
lead resistances are compensated for, which allows a
much greater accuracy in measurements. Each Kelvin
probe assembly has two probe tips. When contacting
the test object it will be contacted with two plus two
probe tips. One pair is for the current generated. The
other pair will measure the very small voltage present.
Principle for the 4 wire Kelvin test.