Vanguard ATO-600 User Manual
OPERATING INSTRUCTIONS
Vanguard Instruments Company, Inc.
for the
ATO-400 and ATO-600
10-400/600 Amperes
Digital Micro-Ohm Meters
1710 Grevillea Court
Ontario, California 91761
TEL: (909) 923-9390 May 2005
FAX: (909) 923-9391 Rev. 1
ATO-400 / ATO-600 Operating Procedures
SAFETY SUMMARY
NOTICE
This manual applies to Models ATO-400, and ATO-600. The operating procedures are
virtually the same for all models; any differences are clearly described in the step-by-step
procedures.
Follow Exact Operating Procedures
Any deviation from the procedures described in this operator’s manual may create one or more
safety hazards, damage the ATO, or cause errors in the test results; Vanguard Instruments Co.,
Inc. assumes no liability for unsafe or improper use of the ATO.
The following safety precautions must be observed during all phases of test set-up, test hookups,
testing, and test-lead disconnects.
SAFETY WARNINGS AND CAUTIONS
This device shall be used only by trained operators.
All circuit breakers under test shall be off line and fully isolated.
Do Not Modify Test Equipment
Because of the risk of introducing unknown hazards, do not install substitute parts or perform
any unauthorized modification to any Model ATO Test Unit. To ensure that all designed safety
features are maintained, it is recommended that repairs be performed only by Vanguard
Instruments Co. factory personnel or by an authorized repair service. Unauthorized
modifications can cause serious safety hazards and will nullify the manufacturer's warranty.
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ATO-400 / ATO-600 Operating Procedures
Table of Contents
1.0 INTRODUCTION ...............................................................................................................6
1.1 Applicability .....................................................................................................................6
1.2 General Description...........................................................................................................6
1.3 Functional Description......................................................................................................6
1.4 Furnished Test Accessories ...............................................................................................6
1.5 Optional Accessories.........................................................................................................7
2.0 ATO SPECIFICATIONS.....................................................................................................9
2.1 ATO-400 Specifications....................................................................................................9
2.2 ATO-600 Specifications..................................................................................................10
3.0 CONTROL AND DISPLAY..............................................................................................11
3.1 ATO-400 Front Panel......................................................................................................11
3.2 ATO-600 Front Panel......................................................................................................13
4.0 ATO IMPORTANT FEATURES.......................................................................................15
4.1 Operating Voltages..........................................................................................................15
4.2 ATO RS-232C Serial Interface.......................................................................................15
4.3 ATO USB Interface........................................................................................................15
4.4 ATO LCD Contrast Adjustment.....................................................................................15
5.0 ATO CABLE CONNECTION...........................................................................................16
6.0 OPERATING PROCEDURES...........................................................................................17
6.1 Step-by-Step Procedures ................................................................................................17
6.1.1 Precautions...................................................................................................................17
6.1.2 Preparations..................................................................................................................17
6.2 Operating Overview........................................................................................................17
6.2.1 Entering Alpha/Numeric Characters.............................................................................18
6.3 Run Normal Test Procedure............................................................................................21
6.4 Run Automatic Test Procedure........................................................................................25
6.5 Enter Record ID Procedure..............................................................................................28
6.6 Review Record Procedure...............................................................................................30
6.7 Restore Record Procedure...............................................................................................31
6.8 Erase Test Record Procedure...........................................................................................33
6.9 Computer Control............................................................................................................34
6.10 Set ATO Clock Procedure.............................................................................................35
6.11 Calibration Test Procedure............................................................................................36
6.12 Diagnostic Check Procedure..........................................................................................40
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ATO-400 / ATO-600 Operating Procedures
List of Figures
Figure 1 ATO Current Cable......................................................................................................7
Figure 2 ATO Sensing cable ......................................................................................................8
Figure 3 C-Clamp Cable ............................................................................................................8
Figure 4 ATO-400 Control-Panel Controls and Display ...........................................................11
Figure 5 ATO-600 Control-Panel Controls and Display ...........................................................13
Figure 6 ATO-400 Connection Diagram ..................................................................................16
Figure 7 ATO-600 Connection Diagram ..................................................................................16
Figure 8 START Menu ............................................................................................................17
Figure 9 SETUP Menu.............................................................................................................18
Figure 10 Step-by Step Procedures for for ATO Operations.....................................................19
Figure 11 Diagnostic Test Cable Connection............................................................................41
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ATO-400 / ATO-600 Operating Procedures
List of Tables
Table 1.0 ATO-400 Specifications.............................................................................................9
Table 2.0 ATO-600 Specifications...........................................................................................10
Table 3.0 Functional Description of ATO-400 Controls and Display........................................12
Table 4.0 Functional Description of ATO-600 Controls and Display........................................14
Table 5.0 Run Test Procedure (Measure an Unknown Resistance) ...........................................21
Table 6.0 Run Automatic Test Procedure (Measure an Unknown Resistance)..........................25
Table 7.0 Enter Record ID Procedure (test-record, site, and equipment identification) .............28
Table 8.0 Review Record Procedure ........................................................................................30
Table 9.0 Restore Record Procedure ........................................................................................31
Table 10.0 Erase Test Record Procedure..................................................................................33
Table 11.0 Set ATO Real Time Clock Procedure.....................................................................35
Table 12.0 Calibration Test Procedure .....................................................................................36
Table 13.0 Diagnostic Check Procedure...................................................................................40
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ATO-400 / ATO-600 Operating Procedures
1.0 INTRODUCTION
1.1 Applicability
This manual applies to the Model ATO-400™ and Model ATO-600™ (hereafter, ATO), made
by Vanguard Instruments Company, Inc.
1.2 General Description
The ATO-400/600 are third generation micro-ohmmeters made by Vanguard Instruments
Company. The ATO-400/600 feature high accuracy microprocessor-controlled measurement of
very low resistances, ranging from 1 micro-ohm to 300 milli-ohms. The ATO is field-portable,
rugged, and is easily operated by first-time users having a minimum of training. It features a 16key push button keypad for entering test parameters and control functions and a 4-line by 20character LCD alpha/numeric readout for displaying control-option menus, measured resistance
values, and related data. The operation requires little more than connecting test leads to an
unknown resistance and selecting the desired functions and its options. Operators select the test
current (10 to 400 amperes for the ATO-400 or 10 to 600 amperes for the ATO-600) and test
time (5 to 60 seconds). Measured resistance data is displayed on the ATO’s LCD. 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 or down loading to the PC. Down loading test records is accomplished by
using the ATO’s built-in RS-232C or USB ports.
1.3 Functional Description
The ATO’s operation is based on the electrical relationship 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 circuit breaker’s contacts). Since the current (user selected) through the unknown
resistance is known and the voltage across the unknown resistance is measured by a precision
voltmeter, the resistance displayed on the LCD is calculated using Ohm’s law. The ATO test
voltage is supplied by an unfiltered DC power supply. A regulated constant-current source
outputs the preset current selected by the user.
The DC test current is selectable from 10 to 400 amperes for the ATO-400 and from 10 to 600
amperes for ATO-600. Since the ATO-400 and ATO-600 use unfiltered DC current supplies,
there is the possibility of inductively tripping a circuit breaker bus differential relay. Each
ATO is supplied with a set of current cables and voltage sensing cables. Voltage sensing test
cables are separate from the current-carrying test cables to the resistive load. Thus, voltages are
measured at the terminals of the resistance being tested, eliminating any I•R voltage drop error in
the current cables. These ATO features make very precise micro-ohm measurements possible
without having to compensate for current-lead resistance errors.
1.4 Furnished Test Accessories
The ATO is supplied with two 15-foot (#1/0 AWG) test cables with heavy-duty alligator clamps
and two 15-foot voltage-sensing cables with alligator clamps. A ground cable and power cord is
also included with each ATO.
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ATO-400 / ATO-600 Operating Procedures
1.5 Optional Accessories
1. Heavy-duty welding-type C-clamps (Figure 3) are available as optional accessories. These C-
clamps allow test lead connections to a wide variety of bushing sizes, bus bars, and
conductors that require low-resistance test-lead contacts.
2. An optional shipping case (which holds the ATO and its cables) is also available.
Figure 1 ATO Current Cable
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ATO-400 / ATO-600 Operating Procedures
Figure 2 ATO Sensing cable
Figure 3 C-Clamp Cable
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ATO-400 / ATO-600 Operating Procedures
2.0 ATO SPECIFICATIONS
2.1 ATO-400 Specifications
ATO-400 specifications and leading particulars are listed in Table 1.0
Table 1.0 ATO-400 Specifications
MODEL.......................ATO-400
TYPE............................Special-Purpose Test Equipment, Portable, Low Resistance-Ohmmeter
CONFIGURATION...... Third-generation (improved design, superseding original model)
SIZE (inches)..............16.8 Wide by 12.6 High by 10.6 Deep (42.7 Cm x 32 Cm x 30.5 Cm)
WEIGHT.......................43 pounds (19.5 Kg)
TEST CURRENT
RANGE ........................10 Amperes to 400 Amperes, selectable in 1 ampere steps
RESISTANCE
RANGE ........................1 micro-ohm to 300 milli-ohms
ACCURACY................ ± 1 % Reading, ± 1 Count
MEMORY.....................63 records of 96 reading each
DISPLAY......................Backlit LCD, 4-lines high by 20 characters wide
CONTROL...................Keypad: 10 number keys and 6 function keys
INPUT POWER...........20 amps, 90-230 Vac, 50/60 Hz, with built in 25A circuit breaker
UNIT PROTECTION...Thermal-overload sensor and cutoff
INTERFACE................ RS-232C and USB Ports for PC Interface
ENVIRONMENT.......... Operating: -10°C to 50°C (15?F to 122?F)
Storage: -30°C to 70°C (-22?F to 158?F)
FURNISHED ITEMS... One power cord, one ground cable, 15-ft.(#1/0 AWG) current test
cables, 15-ft. sensing test cables
WARRANTY................ One-Year Parts & Labor (Post-Warranty Service Contracts Available)
ATO-400 SPECIFICATIONS ARE SUBJECT TO UPGRADES AND MAY BE CHANGED WITHOUT PRIOR NOTICE.
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ATO-400 / ATO-600 Operating Procedures
2.2 ATO-600 Specifications
ATO-600 specifications and leading particulars are listed in Table 2.0
Table 2.0 ATO-600 Specifications
MODEL.......................ATO-600
TYPE............................Special-Purpose Test Equipment, Portable, Low Resistance-Ohmmeter
CONFIGURATION...... Third-generation (improved design, superseding original model)
SIZE (inches)..............16.8 Wide by 12.6 High by 10.6 Deep (42.7 Cm x 32 Cm x 30.5 Cm)
WEIGHT.......................43 pounds (19.5 Kg)
TEST CURRENT
RANGE ........................10 Amperes to 600 Amperes, selectable in 1 ampere steps
RESISTANCE
RANGE ........................1 micro-ohm to 300 milli-ohms
ACCURACY................ ± 1 % Reading, ± 1 Count
MEMORY.....................63 records of 96 reading each
DISPLAY......................Backlit LCD, 4-lines high by 20 characters wide
CONTROL...................Keypad: 10 number keys and 6 function keys
INPUT POWER...........20 amps, 90-230 Vac, 50/60 Hz, with built in 25A circuit breaker
UNIT PROTECTION...Thermal-overload sensor and cutoff
INTERFACE................ RS-232C and USB Ports for PC Interface
ENVIRONMENT.......... Operating: -10°C to 50°C (15?F to 122?F)
......................................Storage: -30°C to 70°C (-22?F to 158?F)
FURNISHED ITEMS... One power cord, one ground cable, 15-ft. (#1/0 AWG) current test lead
......................................cables, 15-ft. sensing test lead cables
WARRANTY................ One-Year Parts & Labor (Post-Warranty Service Contracts Available)
ATO-600 SPECIFICATIONS ARE SUBJECT TO UPGRADES AND MAY BE CHANGED WITHOUT PRIOR NOTICE.
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ATO-400 / ATO-600 Operating Procedures
3.0 CONTROL AND DISPLAY
3.1 ATO-400 Front Panel
The ATO-400 controls and displays are shown in the control-panel illustration, Figure 4.
Pointing leader lines reference each item with an index number. Each index number is crossreferenced to a functional description in Table 3, which describes the function and purpose of
each item on the control panel. Although the purpose of these controls and the display may seem
obvious and intuitive, users should become familiar with them before attempting to use the
ATO-400. First-time users should also review and become familiar with the Safety Summary on
the front page.
Figure 4 ATO-400 Control-Panel Controls and Display
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ATO-400 / ATO-600 Operating Procedures
Table 3.0 Functional Description of ATO-400 Controls and Display
Figure 1
Index #
1 & 12 (Wing Nut) Current lead connectors.
2 USB USB connector. USB port is for factory
3
4 HIGH CURRENT
Adjacent Panel Marking Functional Description
calibration, firmware updates, and interfacing
with the software program supplied with each
unit.
RS-232C
PRESENT
RS-232C interface port; 9-pin connector;
female DB type. The data are set to 115,200
baud, 1 start bit, 8 data bits, and no parity bit;
PIN ...............SIGNAL
2 Rx
3 Tx
5 Signal Gnd
This serial port is for factory calibration,
firmware updates, and interfacing with the
software program supplied with each unit.
LED indicator, red; Lights when test current
is flowing through the current test leads.
5 No Marking Input power connector with third-wire safety
ground.
6 GROUND
(Wing Nut)
7 No Marking
8
No marking
9
No marking
10 & 11 (Resistor Symbol) Voltage-sensing connector jacks (red).
ATO-400 ground stud. Connect ground stud
to substation ground using provided cable.
Circuit breaker, 25A.
LCD; 4-line by 20-character; back-lighted;
displays menus of selections, operator entries,
and test-measurement results.
Operating key-pad controls, 10 alpha-numeric
keys and 6 function keys (START, STOP,
CLEAR, ENTER, & CONTRAST/PAPER
positioning ? & ?).
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ATO-400 / ATO-600 Operating Procedures
3.2 ATO-600 Front Panel
The ATO-600 controls and displays are shown in the control-panel illustration, Figure 5.
Pointing leader lines reference each item with an index number. Each index number is crossreferenced to a functional description in Table 4, which describes the function and purpose of
each item on the control panel. Although the purpose of these controls and the display may seem
obvious and intuitive, users should become familiar with them before attempting to use the
ATO-600. First-time users should also review and become familiar with the Safety Summary on
the front page.
Figure 5 ATO-600 Control-Panel Controls and Display
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