Vanguard Accu-Trans User Manual

OPERATING INSTRUCTIONS

for the

ACCU-TRANS™

TRANSFORMER-WINDING

RESISTANCE METER

Series II

Part Number VIC-8000-S2

Vanguard Instruments Company

1710 Grevillea Court
Ontario, California 91761

TEL: [phone] July 2001
FAX: [phone] Rev 0

Accu-Trans Operating Procedures

SAFETY SUMMARY

The following safety precautions must be
observed during all phases of test set-up, test
hookups, testing, and test-lead disconnects.

Do Not Service or Test Alone

Do not perform test procedures or service
unless another person is also present who is
capable of rendering aid and resuscitation.

Avoid Contact with High Voltage

Because electric utility station environments
contain high voltages and currents, there’s
always the possibility of personal contact with
an unexpected lethal voltages generated by
magnetically induced and/or electrostatic
leakage from nearby live circuitry. When test
units are connected to de-energized ("dead")
lines, regardless of how short these lines may
be, always discharge the lines before
attaching test lead. Because of the possibly
deadly consequences of physical contact with
such lines, engineers and technicians must
always treat electrical equipment and hookups
as though a lethal condition will eventually
occur. Therefore, no matter how unlikely it
may be, never assume anything about the
safety of any test setup.
Ensure the safety of personal by checking

first-hand to eliminate every possible hazard!

Avoid Contact With High-Voltage “Kicks”

Any transformer with many windings turns
and an iron core supports induced magnetic
fields, such that even low-level test currents
produce a magnetic field that, if interrupted,

can produce a high-voltage spike capable of
causing severe injury or death. Accordingly,
its important for personnel safety that test
leads be securely attached to the transformer
terminals to prevent their being accidentally
disconnected during testing. All personnel
are warned to stand clear of the transformer
during all testing. Test technicians should
always ensure that all non-technical personnel
(who may not understand the hazards) be
required to stand clear of all transformers and
equipment during all phases of transformer
testing.

Do Not Modify Test Equipment

Because of the added risk of introducing
additional or unknown hazards, do not install
substitute parts or perform any unauthorized
modification to the Accu-Trans. To ensure all
designed safety features are maintained, it is
recommended that all Accu-Trans repairs be
performed at Vanguard Instruments Co. or by
an authorized repair-service. Unauthorized
equipment modifications can create safety
hazards and will void the Accu-Trans
warranty.

Follow Exact Operating Procedures

Any deviation from the operating
procedures described in this manual may
create one or more safety hazards, damage
the unit or cause test result errors; Vanguard
Instruments Co. assumes no liability for
unsafe or improper use of the Accu-Trans.

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Accu-Trans Operating Procedures

1

Table of Contents

SAFETY SUMMARY................................................................................................................. I

1.0 INTRODUCTION...................................................................................................................3

1.1 APPLICABILITY................................................................................................................3

1.2 SUPERSEDURE NOTICE..................................................................................................3

1.3 GENERAL DESCRIPTION................................................................................................3

1.4 FUNCTIONAL DES CRIPTION.........................................................................................3

1.5 FURNISHED ACCESSORIES ...........................................................................................3

2.0 ACCU-TRANS SPECIFICATIONS.......................................................................................4

3.0 CONTROLS and INDICATORS ............................................................................................5

4.0 PRETEST SETUP ...................................................................................................................7

4.1 OPERATING VOLTAGES.................................................................................................7

4.2 ACCU-TRANS LCD CONTRAST CONTROL.................................................................8

4.3 ACCU-TRANS PRINTER PAPER CONTROL.................................................................8

5.0 ACCU-TRANS PRINTER PAPER.........................................................................................8

6.0 OPERATING PROCEDURES................................................................................................8

6.1 GENERAL PROCEDURES................................................................................................8

6.2 STEP-BY-STEP PROCEDURES AT START-UP MENU..............................................10

6.2.1 START-UP MENU:.......................................................................................................10

6.2.2 TEST TRANSFORM ER PROCEDURE.......................................................................10

6.3 SETUP MENU:..................................................................................................................11

6.3.1 TRANSFORMER ID ENTRIES:..................................................................................12

6.3.2 REVIEW TEST RECORDS PROCEDURE .................................................................13

6.3.3 RESTORE RECORDING PROCEDURES ..................................................................14

6.3.4 PRINTING TEST-RECORD DIRECTORY.................................................................15

6.3.5. ERASE RECORDING PROCEDURE..........................................................................17

6.3.6 ENABLING COMPUTER INTERFACE.....................................................................18

6.3.7 SETTING DATE AND TIME.......................................................................................18

6.3.8 ENABLE PASSIVE TEST MODE ...............................................................................19

6.3.9 VOLTAGE REGULATOR TEST.................................................................................19

Accu-Trans Operating Procedures

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Table of Figure

Figure 1.0 Accu-Trans Controls and Indicators............................................................................5

Figure 2.0 90 to 130Vac Jumper Setting.......................................................................................7

Figure 3.0 210 to 240Vac Jumper Setting.....................................................................................7

Figure 4.0 Summary of Step-by-Step Accu-Trans Operat ion.......................................................9

Figure 5.0 Typical Test Report Printout......................................................................................12

Figure 6.0 Typical Record Directory Printout .............................................................................17

Accu-Trans Operating Procedures

3

1.0 INTRODUCTION

1.1 Applicability

This manual applies to a second-generation
Accu-Trans™ (Series II, henceforth, called
the Accu-Trans), part number VIC-80000­S2 manufactured by the Vanguard
Instruments Co. A prior manual supports a
first generation Accu-Trans (i.e., a Series I
configuration).

1.2 Supersedure Notice

This Operator’s manual is the basic issue for
the Accu-Trans and does not supersede any
previously published manual.

1.3 General Description

Vanguard Instruments Company produces
the Accu-Trans, a microprocessor-controlled
winding resistance meter that measures low
resistances of a transformer’s inductive
windings, in a range from 1 micro-ohm to
200 ohms with very high accuracy. This
instrument can also measure any low
milliohm resistance (e.g., the contact
resistance of a circuit breaker).
This Accu-Trans is simple-to-use; it features
keypad controls and an alpha/numeric
display of the measured resistance, test
current, and operator-entered test parameters
and identifying data.
The Accu-Trans uses a 48-volt dc power
supply and a special current-regulator to
quickly measure transformer-winding
resistances. A typical single- phase 400MVA

transformer winding resistance can be
measured in less than 3 minutes. To ensure

operator safety, the Accu-Trans
automatically discharges the energy stored
in the transformer at the end of each test.
A built-in thermal printer prints test results
on 2.5-inch-wide thermal paper. Resistance
and test current display on a 4-line by 20­character, back lighted LCD. Up to 63
records (96 readings each) can be stored in
the Accu-Trans FLASH EEPROM. The
user can recall stored reports for printing. A
RS-232C serial interface port is provided for

diagnostic testing and down loading test
records.
The Accu-Trans is field-portable, rugged; it
features simple, easy operation by first-time
users with little training.

1.4 Functional Description

The Accu-Trans’s operation is based on the
electrical relationships described by Ohm’s
law: R=V/I, where I is a known current and
V is the dc voltage measured across the
unknown resistance (typically, a circuit­breaker’s contacts). The value of the
unknown resistance under test is the direct
function of the measured voltage divided by
the current and being calculated by the
microprocessor. Resistance reading is then
displayed on a back-lighted 4 line by 20
character LCD.
The Accu-Trans’ 48V dc power supply
applies up to 2 amperes test current to the
device under test. Accu-Trans voltmeter test
leads are run separately from the current­bearing test leads to the resistive load; thus,
voltages are measured at the terminals of the
resistance being measured, eliminating error
from the I•R voltage drop in the test current
cables. The Accu-Trans makes precise
micro-ohm measurements possible without
calculating compensation for test-current­lead resistance errors.
A built-in discharge circuit automatically
discharges the energy stored in the
transformer at the end of each test.

1.5 Furnished Accessories

The Accu-Trans is shipped with two 45-foot
test cables with “quick disconnect” type test
plugs on the unit end and battery-type
clamps at the test load end. One power cord,
one ground cable, and a cable-carrying bag.

Accu-Trans Operating Procedures

4

2.0 ACCU-TRANS SPECIFICATIONS

Table 1. ACCU-TRANS SPECIFICATIONS

TYPE Special-purpose test equipment, portable, micro-ohmmeter
SIZE (inches) 16.8 wide by 12.6 high by 10.6 deep
WEIGHT Less than 21 pounds
RESISTANCE 1 micro-ohm to 200 ohms
TEST CURRENT 2 amperes max
DISPLAY LCD, back-lighted, 4-line by 20-character
PRINTER 2.5-inch wide thermal printer
ACCURACY ± 1 % reading, ± 1 count
POWER 2 amps, 90-120 / 200-240 V ac (selectable), 50/60 Hz
SERIAL INTERFACE RS-232C connector port
ENVIRONMENT Operating: 0°C to 55°C; Storage: -40°C to 65°C
WARRANTY One-year parts & labor (post warranty service is available)

NOTE:
THE ABOVE SPECIFICATIONS ARE VALID AT NOMINAL OPERATING VOLTAGE AND AT A TEMPERATURE OF 25 °C (77°F)

?ACCU-TRANS  SPECIFICATIONS MAY BE UPGRADED AND CHANGED WITHOUT PRIOR NOTICE.

Accu-Trans Operating Procedures

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3.0 CONTROLS AND INDICATORS

(See Figure 1 and refer to Table 1.)
Accu-Trans controls and indicators are
shown in Figure 1.0. A leader line with an
index number points to each control and
indicator, which is cross-referenced to a
functional description in Table 2. This table
describes the function of each item on the

control-panel. The purpose of the controls
and indicators may seem obvious, but users
should become familiar with them before
using the Accu-Trans. Accidental misuse of
the controls will usually cause no serious
harm. Users should also be familiar with the
Safety Summary found on the front page of
this operator’s manual.

Figure 1.0 Accu-Trans Controls and Indicators