Vanguard DMOM-200 User Manual
OPERATING PROCEDURES
for the
MODEL DMOM-200
10-200 Amperes True DC
Digital Micro-Ohm Meter
Part Number VIC-9000-100
Vanguard Instrument Company
1710 Grevillea Court Ontario, California 91761
TEL: 909/923-9390 AUGUST 2001
FAX: 909/923-9391 REV. 0
Operating Procedures DMOM-200™
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 electrical utility station
environments contain high voltages and
currents, there is always the possibility of
personal contact with an unexpected lethal
voltage generated by magnetic induction
and/or electrostatic leakage from nearby live
circuitry. When test units are connected to
deenergized (“dead”) power lines, regardless
of how short they are, always discharge the
lines before attaching any test lead. Because
of the possibly deadly consequences of
physical contact with such high-voltage 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
seem, never assume anything about the safety
of any test setup.
Ensure the safety of personnel by checking
first-hand to eliminate all possible hazards!
Do Not Test Inductive Winding Resistance
Because the DMOM-200 produces test
currents up to 100 amperes, it is able to build
up large magnetic fields in iron-core
transformers. The interruption of such test
currents can produce a high voltage spike
that can cause severe injury, death, and/or
equipment damage. Therefore, do not
attempt to measure the resistance of iron-core
transformer windings (use equipment
designed specifically for that purpose).
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 DMOM-200. To
ensure that designed safety features are
maintained, it is recommended that all
DMOM-200 repairs be done at Vanguard
Instruments Company or by an authorized
repair-service. Unauthorized DMOM-200
modifications can create unknown safety
hazards and will void the warranty.
Follow Exact Operating Procedures
Any deviation from the operating procedures
described in this manual may create one or
more safety hazards, damage the DMOM200 or cause test errors; Vanguard
Instruments Co. assumes no liability for
unsafe or improper use of the DMOM-200.
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Operating Procedures DMOM-200™
TABLE OF CONTENTS
Safety Summary
1.0 INTRODUCTION .................................................................................................................. 1
1.1 Applicability ....................................................................................................................... 1
1.2 Supersedure Notice ............................................................................................................. 1
1.3 General Description ............................................................................................................ 1
1.4 Functional Description........................................................................................................ 1
1.5 Furnished Test Accessories ................................................................................................ 1
2.0 DMOM-200 Specifications ................................................................................................. 2
3.0 CONTROLS AND INDICATORS......................................................................................... 3
4.0 PRETEST SETUP .................................................................................................................. 5
4.1 Operating Voltages ............................................................................................................. 5
4.2 DMOM-200 Printer Paper............................................................................................... 6
4.3 DMOM-200 Cable Connections ..................................................................................... 6
5.0 OPERATING PROCEDURES............................................................................................... 7
5.1 Operating Overview............................................................................................................ 7
5.2 Preparation .......................................................................................................................... 7
5.3 Keying-in Data Characters.................................................................................................. 7
5.4 Run Test Procedure...........................................................................................................10
5.5 Enter ID Procedure ...........................................................................................................13
5.6 Review Record Procedure ................................................................................................ 15
5.7 Restore Record Procedure ................................................................................................ 17
5.8 Print Test Record Directory Procedure............................................................................. 19
5.9 Test Record Procedure...................................................................................................... 20
5.10 Computer Interface Procedure ...................................................................................... 21
5.11 Set Clock Procedures .................................................................................................... 21
5.12 Calibration Check ......................................................................................................... 22
Appendix A DMOM-200 Troubleshooting Guide
Appendix B DMOM-200Cable Accessories
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Operating Procedures DMOM-200™
LIST OF TABLES
Table 1.0 DMOM-200 Specifications and Leading Particulars.................................................. 2
Table 2.0 DMOM-200 Controls and Indicators .......................................................................... 4
Table 3.0 Voltage Selection............................................................................................................ 5
Table 4.0 Run Test Procedure (Measure an Unknown Resistance).............................................. 10
Table 5.0 Run Setup Procedure (test-record, site, and equipment identification)........................ 13
Table 6.0 Review Record Procedure ............................................................................................ 15
Table 7.0 Restore Record Procedures........................................................................................... 17
Table 8.0 Print Test Record Directory.......................................................................................... 19
Table 9.0 Erase Test Record Procedure........................................................................................ 20
Table 10.0 Computer Interface Procedures ................................................................................ 21
Table 11.0 Set Clock Procedures................................................................................................ 21
Table 12.0 Calibration Check Procedure.................................................................................... 22
LIST OF FIGURES
Figure 1.0 DMOM-200 Control Panel (Controls and Indicators) ............................................ 3
Figure 2.0 90 to 130Vac Jumper Setting...................................................................................... 5
Figure 3.0 210 to 240Vac Jumper Setting.................................................................................... 5
Figure 4.0 DMOM-200 Cable Connection............................................................................... 6
Figure 5.0 Step-by-Step Procedures for DMOM-200 Operations............................................ 8
Figure 6.0 Typical DMOM-200 Tabulated Report Printout................................................... 12
Figure 7.0 Typical Directory Printout ........................................................................................ 19
Figure 8.0 Bus Bar Connection .................................................................................................. 23
iii
Operating Procedures DMOM-200™
1.0 INTRODUCTION
1.1 Applicability
This manual applies to the Model DMOM200™, part number VIC-9000-100, which is
made by Vanguard Instruments Company.
1.2 Supersedure Notice
This manual is the basic issue for the Model
DMOM-200 and does not supersede any
published document.
1.3 General Description
The DMOM-200™ is a Digital Micro-Ohm
Meter for precisely measuring non-inductive
resistances from 1 micro-ohm to 300 milliohms. Applications include resistance
measurement of circuit-breaker contacts,
bushing joints, or any other low resistance.
It is field-portable, rugged, and easily
operated by first-time users having little
training (its microprocessor-driven, which
automates many functions). It has a 16-key
pushbutton pad for entering test parameters
and control functions, and a 4-line by 20character LCD readout for displaying
control-option menus, measured resistance
values, and related identifying data. The
DMOM-200 has a built-in thermal printer,
which prints test data on 2.5-inch-wide
thermally sensitive paper.
Operation requires little more than
connecting the test leads to an unknown
resistance and selecting the test parameters;
It requires no calculation of lead-loss, handwritten notes, or the memorizing of detailed
routines. Operators select the test current
(10 to 200 amperes) and test time (5 to 60
seconds). Measured resistance data is
displayed and can be printed on the thermal
printer. The measured resistance data can
also be stored (up to 63 records of 96
readings each) in FLASH EEPROM
memory; Operators can recall the stored
resistance-measurements and related data at
a later time for review and printing.
1.4 Functional Description
DMOM-200 operation is based on the
electrical relationships described by Ohm’s
law: R=V/I, where I is a known test current
and V is the voltage across the unknown
resistance (e.g., breaker contacts). Since the
test current through the unknown resistance
is known and voltage across it is read by the
microprocessor, the resistance is calculated
using Ohm’s law.
The DMOM-200 test voltage is supplied
by a filtered direct-current power supply. A
precisely regulated constant-current source
controls the current ramps up/down time and
the test current. The dc test current (10 to
200 amps) slowly ramps up/down, which
virtually eliminates magnetically induced
transients; thus, the risk of inductively
tripping a circuit-breaker’s bus differential
relay is virtually non-existent.
DMOM-200 voltmeter test leads are run
separately from the current-bearing 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 DMOM-200 makes precise microohm measurements possible without
calculating compensation for test-currentlead resistance errors.
1.5 Furnished Test Accessories
The DMOM-200 is supplied with a power
cord, a roll of 2.5-inch-wide printer paper,
and one 35-foot test cable set with quickdisconnect plugs to the unit and heavy-duty
alligator clamps to the load. Heavy-duty
welding-type C-clamps (see Appendix B)
are also available as optional accessories (Cclamps allow test- lead connection to a wide
variety of bushing sizes, bus bars, and many
other junctions that require low-contact
resistance).
1
Operating Procedures DMOM-200™
2.0 DMOM-200 SPECIFICATIONS
Table 1.0 DMOM-200 Specifications and Leading Particulars
MODEL .............................................DMOM-200 (part number VIC-9000-100)
TYPE..……… ..................................Special-purpose test equipment, portable; 100-ampere,
Digital Micro-Ohm Meter
POWER ............................................85 to 132 V ac or 200-240 V ac (selectable), 50/60 Hz
SIZE (inches) ....................................16.8 wide by 12.6 high by 10.6 deep
WEIGHT............................................ Less than 21 lbs
TEST CURRENT .............................. 10 to 200 amperes
RESISTANCE READING RANGE ...1 micro-ohm to 300 milliohms
ACCURACY .....................................±1% reading, ± 1 count
DISPLAY ..........................................LCD, 4-line by 20-character, back lighted
CONTROLS......................................Keypad: 10 number keys and 6 function keys
COMPUTER INTERFACE ................RS-232C
PRINTER ..........................................Thermal printer (prints on 2.5-inch-wide thermal paper)
ENVIRONMENT ...............................Operating: 0°C to 55°C; Storage: -40°C to 65°C
FURNISHED ..................................... One power cord, one 35-foot test cable set,
One cable bag
EXPENDABLES ............................... Paper, thermally sensitive, 2.5-inch wide roll
(VIC part # TP-3)
WARRANTY ..................................... One-year warranty on parts and labor; post warranty
service contracts available
NOTE:
THE ABOVE SPECIFICATIONS ARE VALID AT NOMINAL OPERATING VOLTAGE AND AT A TEMPERATURE OF 25°C
°
F)
(77
DMOM-200 SPECIFICATIONS MAY BE UPGRADED AND CHANGED WITHOUT PRIOR NOTICE.
2
Operating Procedures DMOM-200™
3.0 CONTROLS AND INDICATORS
(See Figure 1.0 and refer to Table 2.0).
The DMOM-200 controls and indicators
are shown in a panel illustration (see Figure
1.0). Pointing leader lines reference each
item in the figure with an index number.
Each index number is cross-referenced to a
functional description in Table 2.0, which
describes the purpose of each item on the
control panel. Although the purpose of
these controls and the display may seem
obvious, users should become familiar with
them before attempting to use the DMOM200. However, accidental misuse of the
controls will usually cause no serious loss of
data or equipment damage. First-time users
should review and become familiar with the
Safety Summary located in the front section
of this manual.
Figure 1.0 DMOM-200 Control Panel (Controls and Indicators)
3
Operating Procedures DMOM-200™
Table 2.0 DMOM-200 Controls and Indicators
Fig. 1
Index PANEL MARKING FUNCTIONAL DESCRIPTION
1
2
3
4
5
6
7
8
3.1 DMOM-200 LCD Contrast Control
To Darken the LCD display, press and hold
the “Paper ∧ Contrast” switch for two
seconds; to lighten the LCD display, press
and hold the “Paper ∨ Contrast” switch for
two seconds.
(no overall marking; keys are
individually marked—see
ON/OFF
RS-232C
(no marking) Display, back-lighted liquid crystal (LCD); 4-line
(no marking) Built-in thermal printer; prints test result data on
Figure 1)
HIGH CURRENT
PRESENT
(no marking) Voltage-sensing test-lead plug-in sockets (2), red;
(no marking) Test-current lead plug-in sockets (2), red;
Input power connector with third-wire safety
ground and 10A built-in circuit breaker.
Connector, 9-pin; Serial interface-port connector
(female DB type) to allow the DMOM-200 to
be controlled by an IBM-compatible PC.
PIN SIGNAL
2 Tx
3 Rx
5 Signal Gnd
by 20-character; sunlight readable; displays test
menus (operator options), status, and test results
(See Figure 2 for operating displays of control
steps in logical flow sequence).
2.5-inch-wide thermal paper.
Operating key-pad controls; 10 alpha-numeric
keys and 6 function keys (i.e., START, STOP,
CLEAR, ENTER, & CONTRAST/PAPER
positioning ∧ & ∨).
Warning indicator; red LED; Lights when high
current is running through the test leads.
reads voltage at test load.
conducts up to 100 amperes through unknown
resistances.
3.3 RS-232C Computer-Interface port
An IBM PC software package is supplied
with each DMOM-200 allows the user to
retrieve test records stored in the DMOM200 memory.
3.2 DMOM-200 Printer Control
To advance printer paper, press “Paper ∧
Contrast” switch once. Paper will advance
from printer. Press “Paper ∨ Contrast”
switch once, paper will advance backward
from printer.
4
Operating Procedures DMOM-200™
PRETEST SETUP
4.1 Operating Voltages
The DMOM-200 operating voltages are
selectable between 90-130Vac, 50/60Hz or
210-240, 50/60Hz. Voltage selection is set
Table 3.0 Voltage Selection
VOLTAGE SELECTION TERMINAL BLOCK JUMPERS
90-130Vac Brown to blue & yellow to green
210-240Vac Blue to yellow
by the placement of jumpers on the power
terminal block as listed in Table 3.0 below
and Figures 2.0 and 3.0.
120Vac Jumper Installation
Figure 2.0 90 to 130Vac Jumper Setting
Figure 3.0 210 to 240Vac Jumper Setting
5
220Vac Jumper Installation
Operating Procedures DMOM-200™
4.2 DMOM-200 Printer Paper
The DMOM-200 printer uses 2.5-inch
wide thermal paper for printing test results.
We recommend that to maintain the highest
quality printing and to avoid paper jamming,
use paper supplied by our factory. Paper
can be ordered from two sources, as follows:
Vanguard Instruments Co, Inc.
1710 Grevillea Court
Ontario, CA 91761
Tel: 909-923-9390
Fax: 909-923-9391
Part Number: TP-3 Paper
OR
BG Instrument Co.
Route 1, Box 258
Mead, WA 99201
Tel: 509-893-9881
Fax: 509-893-9803
Part Number: TP-3 paper
4.3 DMOM-200 Cable Connections
The DMOM-200 is supplied with a 35foot test cable set. Each cable consists of a
current-carrying cable and a voltage-sensing
cable. The current-carrying cable is
terminated with a 100-ampere male plug.
The sensing cable is terminated with a 25ampere female plug. Insert the current-cable
plugs and voltage-sensing plugs into their
respective control-panel jacks (see Figure
4.0 below). Ensure that voltage plugs
(smaller) are inserted into jacks adjacent to
their companion current jacks (larger).
Figure 4.0 DMOM-200 Cable Connection
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