Megger MLR10 User manual

AVTMMLR10
Rev 5
Jan 2013
Instruction Manual
MLR10
MLR10-47
Leakage Reactance Tester
Catalog No. MLR10
Read this entire manual before operating.
M
Valley Forge Corporate Center
2621 Van Buren Avenue
Norristown, PA 19403-2329
U.S.A.
610-676-8500
www.megger.com

MLR10
Leakage Reactance Tester

Copyright© 2009 by Megger. All rights reserved.
The information presented in this manual is believed to be adequate for the intended use of the product. If the
product or its individual instruments are used for purposes other than those specified herein, confirmation of
their validity and suitability must be obtained from Megger. Refer to the warranty information below.
Specifications are subject to change without notice.
WARRANTY
Products supplied by Megger are warranted against defects in material and workmanship for a period of one
year following shipment. Our liability is specifically limited to replacing or repairing, at our option, defective
equipment. Equipment returned to the factory for repair must be shipped prepaid and insured. Contact your
MEGGER representative for instructions and a return authorization (RA) number. Please indicate all pertinent
information, including problem symptoms. Also specify the serial number and the catalog number of the unit.
This warranty does not include batteries, lamps or other expendable items, where the original manufacturer’s
warranty shall apply. We make no other warranty. The warranty is void in the event of abuse (failure to follow
recommended operating procedures) or failure by the customer to perform specific maintenance as indicated in
this manual.
M
Valley Forge Corporate Center
2621 Van Buren Ave
Norristown, PA 19403-2329
610-676-8500 (Telephone)
610-676-8610 (Fax)
www.megger.com

AVTMMLR10 Rev 5 Jan 2013 i
Table of Contents
1 INTRODUCTION .......................................................................................................................................................... 1
Receiving Instructions...................................................................................................................................................... 1
General Information......................................................................................................................................................... 1
2 SAFETY............................................................................................................................................................................. 3
Precautions......................................................................................................................................................................... 3
3 SPECIFICATIONS.......................................................................................................................................................... 5
Minimum PC Recommended System ............................................................................................................................ 6
Software Installation Instructions and Cal Factor loading:......................................................................................... 6
4 LEAKAGE REACTANCE TESTING ....................................................................................................................... 9
Single Phase Transformer................................................................................................................................................ 9
3 Phase Transformer – Per Phase – Y Primary............................................................................................................ 9
3 Phase Transformer – Per Phase – Delta Primary ................................................................................................... 10
3 Phase Transformer – 3 Phase Equivalent ................................................................................................................ 10
Leadset Connections....................................................................................................................................................... 11
Leakage Reactance Test Procedure .............................................................................................................................. 20
Capacitor Bank Test Procedure .................................................................................................................................... 22
5 Repair ................................................................................................................................................................................ 25
List of Figures
Figure 1. Main AC Breaker ................................................................................................................................................. 2
Figure 2. Output Over Current Breaker ........................................................................................................................... 2
Figure 3. Leakage Reactance Test screen........................................................................................................................ 21
Figure 4. Capacitor Bank Test Connection .................................................................................................................... 22
Figure 5. Capacitance Test Screen ................................................................................................................................... 24

AVTMMLR10 Rev 5 Jan 2013
ii
M

AVTMMLR10 Rev 5 Jan 2013 1
1
INTRODUCTION
Receiving Instructions
Check the equipment received against the packing list to ensure that all materials are
present. Notify Megger of any shortage.
Examine the instrument for damage received in transit. If damage is discovered, file a
claim with the carrier at once and notify Megger, giving a detailed description of the
damage.
This instrument has been thoroughly tested and inspected to meet rigid specifications
before being shipped. It is ready for use when set up as indicated in this manual.
General Information
Leakage Reactance
The Megger Leakage Reactance Tester MLR10 is used to measure leakage reactance and
other associated parameters in high voltage power transformers. Leakage reactance, or
more generally leakage impedance, is measured at the transformer primary winding while
the secondary winding is shorted. Ideally (and theoretically), a transformer’s primary and
secondary windings should be 100% coupled by magnetic flux, however, in real
transformers there is always a small amount of leakage flux. Leakage inductance is a
result of this leakage flux. The amount of leakage flux a transformer has is partially
dependent on the configuration of the windings. Since leakage reactance depends on
leakage flux, measuring a transformer’s leakage reactance can give an indication of the
condition of the windings. Changes in the leakage flux, and therefore the leakage

M
AVTMMLR10 Rev 5 Jan 2013
2
reactance, are generally caused by winding mechanical deformation. The mechanical
deformation can occur during shipping, installation, or from a high current event while
the transformer is in operation. Such changes can be detected by comparing before and
after leakage reactance measurement values.
Figure 1. Main AC Breaker Figure 2. Output Over Current Breaker
Capacitance Bank Testing
With the use of the MLR10’s optional capacitance test probe, electrical measurements
can be isolated to individual legs of a complex capacitive bank network. The MLR10 ac
voltage source is applied across the appropriate capacitor section (containing the
capacitance of interest) and the optional capacitance test probe is used to isolate the
measurements specific to the capacitor of interest. .
PC Control
Operation of the MLR10 is conducted while connected to an external companion
laptop/PC. The MLR10 comes complete with the necessary software.

AVTMMLR10 Rev 5 Jan 2013 3
2
SAFETY
Precautions
The test set and the specimen to which it is connected are a possible source of high-
voltage electrical energy and all persons making or assisting in tests must use all practical
safety precautions to prevent contact with energized parts of the test equipment and
related circuits. Persons actually engaged in the test must stand clear of all parts of the
complete high-voltage circuit, including all connections, unless the test set is de-
energized and all parts of the test circuit are grounded. Persons not directly involved
with the work must be kept away from test activities by suitable barriers, barricades, or
warnings.
Treat all terminals of high-voltage power equipment as a potential electric shock hazard.
There is always the potential of voltages being induced at these terminals because of
proximity to energized high-voltage lines or equipment. Always use a safety ground stick
to ground the high-voltage conductor. A safety ground jumper must then be installed
between all terminals of apparatus under test and ground. Always disconnect test leads
from power equipment before attempting to disconnect them at the test set. The ground
connection must be the first made and the last removed. Any interruption of the
grounding connection can create an electric shock hazard.
This instrument operates from a single phase power source. It has a three wire power
cord and requires either a 120V line-neutral-ground or 240V line-line-ground
connection, as below:
MLR10: 120V, 50/60Hz
MLR10-47: 240V, 50/60Hz
Before making connection to the power source, determine that the instrument rating
matches the voltage of the power source and has a suitable two-pole, three-terminal
grounding connector.
The power input plug must be inserted only into a mating receptacle with a ground
contact. Do not bypass the grounding connection. Any interruption of the grounding
connection can create an electric shock hazard. Determine that the receptacle is properly
wired before inserting the plug.
It is not possible to eliminate all potential hazards from, and in using, electrical test
equipment. For this reason, every effort has been made to point out in this instruction

M
AVTMMLR10 Rev 5 Jan 2013
4
manual the proper procedures and precautions to be followed by the user in operating
this equipment and to mark the equipment itself with precautionary warnings where
appropriate. It is not possible to foresee every hazard which may occur in the various
applications of this equipment. It is therefore essential that the user, in addition to
following the safety rules in this manual, also carefully consider all safety aspects of the
test before proceeding.
Safety is the responsibility of the user.
Misuse of this high-voltage equipment can be extremely dangerous.
The purpose of this equipment is limited to use as described in this manual. Do not
use the equipment or its accessories with any device other than specifically described.
Never connect the test set to energized equipment.
Operation is prohibited in rain or snow.
Do not use the test set in an explosive atmosphere.
A qualified operator should be in attendance at all times while the test equipment is
in operation.
Observe all safety warnings marked on the equipment.
Corrective maintenance must only be performed by qualified personnel who are
familiar with the construction and operation of the test set and the hazards involved.
Refer to IEEE 510 - 1983, “IEEE Recommended Practices for Safety in High-
Voltage and High-Power Testing,” for information.
If the test equipment is operated properly and all grounds correctly made, test personnel
need not wear rubber gloves. As a routine safety procedure, however, some users require
that rubber gloves be worn, not only when making connections to the high-voltage
terminals, but also when manipulating the controls. Megger considers this an excellent
safety practice.
High-voltage discharges and other sources of strong electric or magnetic fields may
interfere with the proper functioning of heart pacemakers. Persons with heart
pacemakers should obtain expert advice on the possible risks before operating this
equipment or being close to the equipment during operation.