Belts

P J

HIGH FREQUENCY SURGE TESTER

INSTRUCTION / SERVICE MANUAL

MODEL

6920C (20 KV)

PJ ELECTRONICS, INC. 575 Davidson Road Pittsburgh, PA 15239 USA Phone / Fax: 001 412-793-3912 Visit our web site: www.pjelectronics.com

© PJ Electronics, Inc.

WARNING - HIGH VOLTAGE

THIS EQUIPMENT OPERATES AT VOLTAGES WHICH ARE EXTREMELY DANGEROUS. READ THE FOLLOWING INSTRUCTIONS CAREFULLYBEFORE USING THE TESTER. USE EXTREME CARE AND TAKE SUITABLE PRECAUTIONS WHEN OPERATING AND SERVICING THIS TESTER.

CAUTION
DO NOT OPERATE TESTER BEYOND OUTPUT “KV” RATING OF TESTER. EXCEEDING THE OUTPUT VOLTAGE RATING MAY DAMAGE TESTER AND VOID WARRANTY.

Serial No.

TABLE OF CONTENTS

BRIEF DESCRIPTION . OPERATING PRINCIPLE .

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Page 1-1 Page 2-1 Page 3-1 Page 4-1 Page 5-1 Page Page Page Page 5-1 5-5 5-7 5-10

OPERATOR SAFETY FEATURES . OPERATING PROCEDURE . COIL TESTING PROCEDURES . A. B. C. D. . .

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Introduction . . Air Core Coil Testing . Iron Core Coil Testing Assemblies . . . . .

SERVICE INFORMATION A. B. C. D. E. F. G. H.

Page 6-1 Page PagePage Page Page Page Page Page 6-2 6-2 6-3 6-4 6-5 6-5 6-6 6-7

Circuit Breaker Tripped . . . . Voltage Meter Reading Drops Suddenly . Voltage Meter Reads Very Low . . . No Scope Waveforms . . . . . Blank Scope Face . . . . . Scope Waveform Amplitudes Are Unbalanced . Panel Lights Operating Improperly . . TESTER Cannot Be Energized . . . . . . . . . . . . . . . . .

PARTS LIST .

Page 7-1FIGURES 1 through 12 . WIRING DIAGRAMS . .

Pages 8-1 to 8-11 . . . Appendix A Page A-1 Page A-2 Page A-3 Page A-4 Page A-4 Appendix B Page B-1 Page B-2

A. Wiring Diagram for Control Panel . B. Control Console terminal Strip plus Slip-on connections

C. Drive Control Chassis with Fan and Filament connection . D. Control Chassis with Fan and Filament Transformer E. Power Transformer . . . . .. . . . . . .

THREE PHASE TRANSFER SWITCH (Optional). A. Operating Instructions . B. Wiring Diagrams . . .

BRIEF DESCRIPTION
The P J High Frequency Surge Testers are used to detect defective coil insulation in series fields, shunt fields, armatures, and stators for all types of industrial AC and DC machines during coil manufacturing, installation and connection. It may also be used todetect an incorrect number of turns. Each

surge tester is capable of delivering a continuously variable peak test voltage from an established minimum of 200 volts for Models 6905, 8706 and 400 volts for Models 6910 through 6940. This voltage can be accurately set by a VOLTAGE ADJUST control located on the front panel and can be read directly on a large digital meter mounted in the center of the toppanel. These testers use a comparison

method for detecting defective coil insulation, i.e., the coil-under-test and an identical reference coil are compared to one another. The voltage is applied to

each coil and the resultant current waveform from each coil is displayed on a wideband oscilloscope. If the insulation of both coils is good at the applied (See Figure #1

test voltage,essentially one stable waveform will be observed. on page 8-1).

If, however, the insulation of one of the coils-under-test can no

longer support the level of applied voltage, two distinct waveforms will be observed on the oscilloscope. (See Figure #2). The two distinct waveforms will

appear even for a high resistance short or momentary insulation breakdown.

1-1

OPERATING PRINCIPLEReferring to Figure #3 on page 8-2, the transformer T1 steps up the line voltage to the desired test potential. Capacitors Bank C3 and C4 will charge to the The circuit is

peak of the applied voltage by way of diode D1 and coils L1 and L2.

synchronized so that on the negative half of the AC line voltage, switch ST1 will turn on and discharge C3 through coil L1 and C4 through L2. Thus, the...