Megger MOM200A, MOM600A User Manual

WWW.MEGGER.COM

User’s Manual

Art No.

ZP-BB04E

Doc.

BB0141NE V06 2015

MOM200A/600A

Micro-ohmmeters

MOM200A/600A

Micro-ohmmeters

NOTICE OF COPYRIGHT & PROPRIETARY RIGHTS

© 2013, Megger Sweden AB. All rights reserved.

The contents of this manual are the property of Megger Sweden AB. No part of this work may be reproduced or transmitted in any form or
by any means, except as permitted in written license agreement with Megger Sweden AB. Megger Sweden AB has made every reasonable
attempt to ensure the completeness and accuracy of this document. However, the information contained in this manual is subject to change
without notice, and does not represent a commitment on the part of Megger Sweden AB. Any attached hardware schematics and technical
descriptions, or software listings that disclose source code, are for informational purposes only. Reproduction in whole or in part to create
working hardware or software for other than Megger Sweden AB products is strictly prohibited, except as permitted by written license
agreement with Megger Sweden AB.

TRADEMARK NOTICES

Megger® and Programma® are trademarks registered in the U.S. and other countries. All other brand and product names mentioned in this
document are trademarks or registered trademarks of their respective companies.

Megger Sweden AB is certified according to ISO 9001 and 14001.

User’s Manual

Postal address:

Megger Sweden AB
Box 724
SE-182 17 DANDERYD
SWEDEN

T [phone]
F [phone]

[e-mail]
www.megger.com

Visiting address:

Megger Sweden AB
Rinkebyvägen 19
SE-182 36 DANDERYD
SWEDEN

BB0141NE ZP-BB04E MOM200A/600A

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4 MOM200A/600A ZP-BB04E BB0141NE

Contents

1 Introduction

............................................................. 6

General ..............................................................6

Function description ...........................................6

2 Safety

............................................................. 8

General ..............................................................8

Symbols on the instrument ...................................... 8

Safety instructions ..............................................8

3 Control panels

........................................................... 10

Control panel – MOM200A .............................10

Control panel – MOM600A .............................11

4 Operating instructions

........................................................... 12

External measuring instrument............................... 13

Troubleshooting ..................................................... 13

5 Application examples

........................................................... 14

Measuring resistance in a breaker ....................14

Measuring resistance at bus-bar joints ..............15

Expanded measuring range ..............................16

Application example .............................................. 16

6 Specifications

........................................................... 18

Specifications MOM200A ................................18

Specifications MOM600A ................................18

BB0141NE ZP-BB04E MOM200A/600A

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1 INTRODUCTION

1

Introduction

General

This manual is for the MOM200A, and MOM600A
micro-ohmmeters.

The micro-ohmmeter is designed to measure the
resistances of breaker contacts, bus-bar joints, contact
elements 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 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.

Function description

Connect the instrument to the object being tested.

After you have adjusted the instrument to provide the
desired current through the test object (100 A for ex­ample), the actual voltage drop across the test object
will be measured automatically, and all you have to do
is press a button to display the actual resistance.

High current is generated and sent out by the instru­ment during measurement. A miniature circuit breaker
and a thermal cut-out are provided to make certain
this current doesn’t generate excessive heat inside the
instrument.

The instrument is equipped with a device that guards
against induction. A relay short-circuits the sensing
input when the instrument’s ON/OFF switch is off
and also when the instrument is in the m mode.
To protect against external overvoltages, both the
current output and the sensing input are decoupled to
ground.

MOM200A is used for currents up to 200 A.

MOM600A can provide an output current of up to
600 A, and it can be set to six different measuring
ranges.

Full-wave rectified current is used for measuring.