Megger AVTM6514J User manual

AVTM6514J
Rev. A
March 2003
Instruction Manual AVTM6514J
for
Impulse Generator
Catalog Nos. 651403 and 651404
High-Voltage Equipment
Read the entire manual before operating.
Aparato de Alto Voltaje
Antes de operar este producto lea este manual enteramente.
PO Box 9007
Valley Forge, PA 19485-1007 U.S.A.
610-676-8500
Shipping Address:
Valley Forge Corporate Center
2621 Van Buren Avenue
Norristown, PA 19403 U.S.A.
www.megger.com

AVTM6514J Rev. A (03/2003)
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Copyright 2003 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. Specifications are subject to change without notice.

AVTM6514J Rev. A (03/2003) i
Table of Contents
SECTION 1 ............................................................................................................................................................ 1
introduction......................................................................................................................................................... 1
Receiving Instructions .................................................................................................................................. 1
General Information ..................................................................................................................................... 1
SECTION 2 ............................................................................................................................................................ 5
Safety.................................................................................................................................................................... 5
SECTION 3 ............................................................................................................................................................ 9
Specifications ...................................................................................................................................................... 9
Electrical ......................................................................................................................................................... 9
Physical............................................................................................................................................................ 9
Environmental ............................................................................................................................................... 9
SECTION 4 .......................................................................................................................................................... 11
Description........................................................................................................................................................ 11
Circuit Descriptions .................................................................................................................................... 11
Controls And Connectors .......................................................................................................................... 13
SECTION 5 .......................................................................................................................................................... 15
Setup .................................................................................................................................................................. 15
SECTION 6 .......................................................................................................................................................... 19
Operation .......................................................................................................................................................... 19
Operating Procedure................................................................................................................................... 19
Interpreting The Output Current Meter .................................................................................................. 19
Shutdown Procedure................................................................................................................................... 20
SECTION 7 .......................................................................................................................................................... 21
Operation Notes .............................................................................................................................................. 21
Theory ........................................................................................................................................................... 21
Impulse Testing ........................................................................................................................................... 22
Operation With An Electromagnetic Impulse Detector ....................................................................... 22
Proof Testing Cable .................................................................................................................................... 22
SECTION 8 .......................................................................................................................................................... 23
Service................................................................................................................................................................ 23
Maintenance ................................................................................................................................................. 23
Performance Check..................................................................................................................................... 24
Troubleshooting And Repair..................................................................................................................... 25
SECTION 9 .......................................................................................................................................................... 29
Replaceable Parts List...................................................................................................................................... 29
GLOSSARY.......................................................................................................................................................... 31

AVTM6514J Rev. A (03/2003)
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WARRANTY........................................................................................................................................................ 33
APPENDIX .......................................................................................................................................................... 35
Brief Operating Instructions...................................................................................................................... 35
FIGURE LIST
Figure 1: Impulse Generator................................................................................................................................. 2
Figure 2: Schematic Diagram.............................................................................................................................. 12
Figure 3: Typical Fault Diagram........................................................................................................................ 21

AVTM6514J Rev. A (03/2003) 1
SECTION 1
Introduction
RECEIVING INSTRUCTIONS
Check the equipment received against the packing list to ensure that all materials are
present. Notify Megger of any shortage. Telephone [phone].
Examine the instrument for possible damage received in transit. If any damage is
discovered, file a claim with the carrier at once and notify Megger or its nearest
authorized sales representative, 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
This instruction manual describes the operation and maintenance of Impulse
Generators having Catalog No. 651403 and 651404. Catalog No. 651403 is the 120 V,
50/60 Hz, 300 VA model, and Catalog No. 651404 is the 240 V, 50/60 Hz, 300 VA
model.
The Impulse Generator produces periodic pulses up to 15 kV for locating faults in
cables by the high-voltage, impulse-tracing method. No larger than a medium-sized
suitcase and weighing only 41 pounds, the Impulse Generator is contained in a
fiberglass carrying case that is rugged and durable to withstand transportation from site
to site. See Figure 1.
The Impulse Generator uses low-voltage storage capacitors on the primary side of a
pulse transformer. Every six seconds, a solid-state switch discharges the capacitors into
the pulse transformer, which steps the voltage up to the required level. The resultant
output is a high-voltage impulse with a steep front and an exponentially decaying "tail"
—an ideal waveform for cable fault location. The waveform travels along the cable
until it reaches the fault, where a sparkover occurs. High-voltage sparkover causes a
significant current to flow, and the fault is located by detecting this current or the noise
made by the sparkover.
An ammeter on the Impulse Generator displays peak fault current in percentage of the
available output. When the meter indicates a cable fault, its location is pinpointed by
tracing the fault current with a detector carried along the cable path. Two such detectors
are available from Megger:

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Figure 1: Impulse Generator

AVTM6514J Rev. A (03/2003) 3
Catalog No. 653000 Surge Detector (for direct buried cable)
Catalog No. 651113 Electromagnetic Impulse Detector (for ducted and buried
cable)
A rotary switch allows the selection of 3, 6, 9, 12, or 15 kV. The switch also has a
ZERO START position which discharges the capacitors and provides a zero-voltage
start-up for safety. Input and output cables are permanently attached; storage for cables
is provided in the lid of the carrying case. An integral fan provides cooling.

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AVTM6514J Rev. A (03/2003) 5
Section 2
Safety
This equipment and the cable to which it is connected are sources of high-voltage
electrical energy. All persons performing 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, by at least 3 ft (0.91 m), of
all parts of the complete high-voltage circuit unless the system 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. Be aware
that impulses applied to the cable will be present at the remote end(s) and any other
exposed part of the cable, usually out of sight of the operator. To avoid inadvertent
contact with hazardous live parts, always ensure that access to all exposed parts of the
cable or connected equipment is restricted, by using suitable barriers or barricades.
§Safety is the responsibility of the user.
§Misuse of this high-voltage equipment can be extremely dangerous.
§The purpose of the test 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 equipment to energized equipment.
§Never use the test equipment if there is any possibility that the test equipment or
cable under test is in an explosive atmosphere.
§A qualified operator should be in attendance at all times while the test equipment is
in operation.
§The safety ground jumpers and surge ground must be properly connected (refer to
Section 5).
§Refer to IEEE 510-1983 "IEEE Recommended Practices for Safety in High-
Voltage and High-Power Testing," and follow the applicable safety
recommendations.
§Observe the safety warnings marked on the equipment.
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 grounding
stick to ground the high-voltage conductor. A safety ground jumper must then be
installed between the high-voltage conductor and ground of the cable under test. The
ground connection must be the first made and the last removed.

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Systems of this type should not be used to locate faults on direct-buried unshielded or
secondary cable. Dangerously high differences in potential may be developed in the
current return path to the system.
Systems of this type should not be used to locate faults on any cable that is likely to be
near enough to an energized cable to allow a burn through of the insulation of the
energized cable. This situation may occur when the cables are located in a common
trench, duct, or tray.
On completion of a test, even after power has been removed from the system, energy
can still be stored in the impulse capacitor and cable under test. To discharge the cable
and capacitor, immediately after use, set the OUTPUT KILOVOLTS switch to ZERO
START. This places a solid ground on the output cable, power supply, and impulse
capacitor.
F
WARNING
Never assume that the coaxial output cable or the cable under
test is completely discharged, even after following the above
procedures. Always use a safety grounding stick to ground any
conductive part of the circuit and then apply safety ground
jumpers before touching any connections.
This system operates from a single-phase power source. It has a three-wire power cord
and a two-pole, three-terminal grounding type connector. The voltage to ground from
either pole of the power source must not exceed the maximum rated operating voltage,
120 V ac for Catalog No. 651403 and 240 V ac for Catalog No. 651404. Before making
connection to the power source, determine that the system is suitable for the voltage of
the power source, and has a suitable two-pole, three-terminal grounding type connector.
The power source must have a high rupture fuse or circuit breaker rated no higher than
15 A.
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
correctly wired before inserting the plug.
To avoid electric shock hazard, operating personnel must not remove the system
protective covers. Component replacement and internal adjustments must be made by
qualified service personnel only.
Users of high-voltage equipment should note that high-voltage discharges and other
sources of strong electric or magnetic fields may interfere with the proper functioning
of heart pacemakers. Personnel using heart pacemakers should obtain expert advice on
the possible risks before operating this equipment or being close to the equipment
during operation.
If the system is operated in accordance with the safety precautions in this manual and if
all grounds are correctly made, rubber gloves are not necessary. 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 controls.
Megger recommends this excellent safety practice.