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MCCB-250
MOLDED-CASE CIRCUIT BREAKER TESTER
USER’S MANUAL
Vanguard Instruments Company, Inc.
1520 S. Hellman Ave.
Ontario, California 91761, USA
TEL: (909) 923-9390
FAX: (909) 923-9391
September 2009
Revision 2
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MCCB-250 USER’S MANUAL REV 2
SAFETY SUMMARY
FOLLOW EXACT OPERATING PROCEDURES
Any deviation from the procedures described in this User’s Manual may create one or more
safety hazards, may damage the MCCB-250, or cause errors in the test results. Vanguard
Instruments Company, Inc. assumes no liability for unsafe or improper use of the MCCB-250.
All safety precautions provided in this manual must be observed during all phases of testing
including test preparation, test lead connection, actual testing, and test lead disconnection.
SAFETY WARNINGS AND CAUTIONS
Only trained operators shall use this device. All circuits under test shall be off-line and fully
isolated.
DO NOT MODIFY TEST EQUIPMENT
To avoid the risk of introducing additional or unknown hazards, do not install substitute parts or
perform any unauthorized modification to any MCCB-250 test unit. To ensure that all designed
safety features are maintained, it is highly recommended that repairs be performed only by
Vanguard Instruments Company factory personnel or by an authorized repair service provider.
Unauthorized modifications can cause safety hazards and will void the manufacturer’s
warranty.
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TABLE OF CONTENTS
CONVENTIONS USED IN THIS DOCUMENT ....................................................................... 1
1.0 INTRODUCTION .................................................................................................................. .. 2
1.1 General Description and Features ................................................................................... 2
1.2 Furnished Accessories ...................................................................................................... 2
1.3 MCCB-250 Technical Specifications ................................................................................. 3
1.4 Controls and Indicators .................................................................................................... 4
2.0 FUNCTIONAL DESCRIPTION ................................................................................................. 6
2.1 MCCB-250 AC Current Source .......................................................................................... 6
2.2 MCCB-250 Current Output Control ................................................................................. 7
2.3 Timer Stop Input and Control .......................................................................................... 8
2.4 MCCB-250 Timer .............................................................................................................. 9
2.5 External Current Input ..................................................................................................... 9
2.6 LCD Contrast Control ....................................................................................................... 9
3.0 OPERATING PROCEDURES ................................................................................................. 10
3.1 Testing the Time Delay of a Protection Relay ................................................................ 10
3.2 Measuring Current Transformer Primary and Secondary Currents .............................. 12
LIST OF TABLES
Table 1. MCCB-250 Technical Specifications .................................................................................. 3
Table 2. Functional Descriptions of MCCB-250 Controls and Indicators ........................................ 5
Table 3. MCCB-250 Current Output ................................................................................................ 6
Table 4. MCCB-250 Overload Current Output ................................................................................ 6
LIST OF FIGURES
Figure 1. MCCB-250 Controls and Indicators .................................................................................. 4
Figure 2. Typical MCCB-250 Test Results Screen ............................................................................ 9
Figure 3. Typical MCCB-250 Application ....................................................................................... 10
Figure 4. Typical Current Transformer Current Ratio Test Connections ...................................... 12
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MCCB-250 USER’S MANUAL REV 2
CONVENTIONS USED IN THIS DOCUMENT
This document uses the following conventions:
• A key, switch, input, or knob on the MCCB-250 is indicated as [KEY], [SWITCH],
[INPUT], [KNOB]
Menu options are referenced as (MENU OPTION).
•
• MCCB-250 LCD screen output is shown as:
1. OPTION 1
2. OPTION 2
3. OPTION 3
4. OPTION 4
• Warning messages are indicated as:
WARNING
.
Warning message
• Important notes are indicated as:
Note details
NOTE
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1.0 INTRODUCTION
1.1 General Description and Features
The MCCB-250 is a programmable, high-current source designed specifically for testing moldedcase circuit breakers as well as thermal, magnetic, or solid-state overload motor-protection
relays.
MCCB-250 Timer
The MCCB-250’s built-in timer can test the time-delay characteristics of protection relays and
molded-case circuit breakers. Once the test is initiated, the current source and the timer are
automatically turned on at the next zero-crossing point of the AC. The timer stops when the
MCCB-250 input detects a change in the dry contact or voltage input, or detects the removal of
the test current. The test results are then displayed in milliseconds and fractions of a cycle(s) on
the unit’s back-lit LCD screen (20 characters by 4 lines).
MCCB-250 Current Source
The MCCB-250 has 4 current-source outputs (5 A @ 120 Vac, 25 A @ 24 Vac, 120 A @ 6 Vac,
250 A @ 3 Vac) that conduct the test current through the high-impedance load circuits. Each
current source can tolerate short-duration over-loads up to 4 times the rated current. This
feature is used for testing the instantaneous trip element of molded-case circuit breakers.
When using this feature, the selected test current is displayed on the LCD screen. When the
MCCB-250 is used as a current source, the current-flow time (the current-on period) is
displayed on the LCD screen.
External Current Input
The MCCB-250 also provides an external current input (0 – 10 A). Both internal and external
current source readings can be viewed at the same time.
1.2 Furnished Accessories
The MCCB-250 comes furnished with the following:
• Two 10-foot #4 AWG current cables with heavy-duty alligator clamps
• One 10-foot #10 AWG current cable
• Two 10-foot external current input cables with alligator clips
• Two 10-foot external timer input cables with alligator clips.
• One ground cable
• One power cord
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1.3 MCCB-250 Technical Specifications
Table 1. MCCB-250 Technical Specifications
TYPE 250 Ampere current source
PHYSICAL SPECIFICATIONS Dimensions: 16.8”W x 12.6”H x 10.6”D (42.6 cm x 32.0 cm x 27.0 cm);
Weight: 46 lbs (21 kg)
INPUT POWER 100 – 120 Vac or 200 – 240 Vac (factory pre-set), 50/60 Hz
OUTPUT CURRENTS 0 – 5 A @ 120 Vac max; 0 – 25 A @ 24 Vac max;
0 – 120 A @ 6 Vac max; 0 – 250 A @ 3 Vac max
INTERNAL CURRENT METER 100 mA – 1000 A; Accuracy: 1% of reading ±20mA
MEASUREMENT METHOD Isolated CT
EXTERNAL METER RANGE 10 mA – 10 A; Accuracy: 1% of reading, ±2mA
MEASUREMENT METHOD Isolated CT
TIMER READING RANGE 1ms – 2 hours; Accuracy: 0.1% of reading ±1ms
TIMER STOP INPUTS Voltage input (24V – 300V, DC or peak AC), dry contact input, or removal
of primary current
DISPLAY Back-lit LCD Screen (20 characters by 4 lines); viewable in bright sunlight
and low-light levels
COMPUTER INTERFACE RS-232C port for factory calibration and diagnostics
SAFETY Designed to meet IEC61010 (1995), UL61010A-1, CSA-C22.2 standards
ENVIRONMENT Operating: -10˚C to 50˚ C (15˚F to +122˚ F); Storage: -30˚ C to 70˚ C (-
22˚F to +158˚ F)
CABLES Power cord, ground cable, two 10-foot (#4 AWG) test leads, one 10-foot
(#10 AWG) test lead , four 10-foot external input cables
OPTIONS Transportation case
WARRANTY One year on parts and labor
MCCB-250 USER’S MANUAL REV 2
The above specifications are valid at nominal operating voltage and at a
temperature of 25°C (77°F). Specifications may change without prior notice.
NOTE
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1.4 Controls and Indicators
The MCCB-250’s controls and indicators are shown in Figure 1. A leader line with an index
number points to each control and indicator, which is cross-referenced to a functional
description in Table 2. The 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 MCCB-250. 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 User’s Manual.
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Figure 1. MCCB-250 Controls and Indicators
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MCCB-250 USER’S MANUAL REV 2
Table 2. Functional Descriptions of MCCB-250 Controls and Indicators
Item
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15 & 16
17
18 & 19
Panel Markings Functional Description
COM Current source common terminal.
250A 250A current source terminal.
120A 120A current source terminal.
25A 25A current source terminal.
5A 5A current source terminal
RS-232C
90-120 Vac
50-60 Hz, 20A
or
200-240 Vac
50-60 Hz, 20A
None Circuit Breaker/Power Switch.
GROUND
CURRENT
CONTROL
HIGH
CURRENT
PRESENT
None
Up and Down
Arrows
CONTRAST LCD screen contrast control.
EXT CURRENT
(0-10A)
DRY CONTACT
WET CONTACT
CURRENT
TIMER STOP Timer “STOP” input connectors.
RS-232C (serial) interface port for factory firmware programming and
diagnostics.
Input power connector.
MCCB-250 ground stud. Connect ground stud to substation ground using
provided cable.
Current control knob.
High current presence indicator LED.
Back-lit LCD screen (20 characters by 4 lines), viewable in bright sunlight and
low-light levels.
The up and down arrows are used to control the current source output and
timer. Three modes are available:
ON+TMR : Turn on current source and timer
OFF: Turn off current source and timer
MONT: Turn on current source momentarily
External current input connectors.
Timer and current source stop input selection with LED indicator.
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A
A
A
A
2.0 FUNCTIONAL DESCRIPTION
2.1 MCCB-250 AC Current Source
The MCCB-250 provides five AC current outputs (items 1, 2, 3, 4, and 5 in Figure 1). AC test
current is set by the
displayed on the LCD screen. The MCCB-250’s output current ratings are shown in Table 3 and
Table 4 below.
[CURRENT CONTROL] knob. This test current is measured and
Table 3. MCCB-250 Current Output
CURRENT OUTPUT
120 Vac @ 5
24 Vac @ 25
6 Vac @ 120
3 Vac @ 250
Table 4. MCCB-250 Overload Current Output
CURRENT ON TIME OFF TIME
100% (1x)
200% (2x)
300% (3x)
400% (4x)
30 Minutes 30 Minutes
3 Minutes 5 Minutes
30 Seconds 4 Minutes
4 seconds 7 Minutes
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2.2 MCCB-250 Current Output Control
The MCCB-250 current source output is controlled by the [UP
ARROW]
and [DOWN ARROW] keys (item 13 in Figure 1). Three
control modes are available: ON+TMR, OFF, and MOMT.
The OFF mode indicates that both the current source output and
timer are off.
The MOMT mode turns on the current source momentarily. To turn on the current source,
press and hold the [DOWN ARROW] key. The LED indicator next to the “MOMT” label will
turn on indicating that the MCCB-250 current source is on. The output current will also be
displayed on the LCD screen. The MCCB-250 current output can now be set by turning the
[CURRENT CONTROL] knob. Release the [DOWN ARROW] key to turn off the current
source.
The ON+TMR mode turns on the MCCB-250 current source and timer. This initiates a test and is
stopped by using the [TIMER STOP] inputs. The test results will be displayed on the LCD
screen. The test can also be terminated by pressing the [DOWN ARROW] key.
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2.3 Timer Stop Input and Control
After a test is started, the MCCB-250 timer can be
stopped and the current source turned off using one of
three modes: dry contact input, wet contact input, or
interruption of the MCCB-250 current output. The
[LEFT ARROW] key is used to select the desired
mode.
When the DRY CONTACT mode is selected, the MCCB250 will output a DC voltage to the
[TIMER STOP]
terminals to sense the state of the dry contacts. A change in this dry contact state will stop the
timer and turn off the current source.
In WET CONTACT mode, the MCCB-250 will sense an AC or DC voltage applied to the [TIMER
STOP]
terminals. The OFF state is a voltage from 0 to 10 V ac/dc. The ON state is a voltage
from 24 to 300 V ac/dc. A change in the voltage state will stop the timer and turn off the
current source.
In CURRENT mode, an interruption of the MCCB-250 current source output (CB contact opened)
will stop the timer and turn off the current source.
Both the DRY CONTACT and WET CONTACT modes require an external input to the MCCB-250
via the [TIMER STOP] terminals.
The MCCB defaults to DRY CONTACT mode when it is first turned on.
NOTE
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2.4 MCCB-250 Timer
The MCCB-250’s built-in time/cycle counter can be used to time events in milliseconds and
cycles. The elapsed time is displayed on the LCD screen along with the test current after a test is
completed. A typical test results screen is shown in Figure 2. The timer is turned on when the
ON+TMR mode is selected.
Figure 2. Typical MCCB-250 Test Results Screen
2.5 External Current Input
The MCCB-250’s [EXT CURRENT] input serves as a built-in ampere meter
that can be used to monitor an AC current. This current is isolated, and the
maximum input current is 10 amperes. A typical application for this feature is to
measure a current transformer (CT) current ratio. The MCCB-250 can be used to
output a current to the CT primary input. The CT secondary output is then
connected to the MCCB-250’s [EXT CURRENT] input. Both the MCCB-250
output current and the CT secondary current are displayed on the LCD screen
(see Figure 2). The user can use the displayed values to quickly calculate the CT
current ratio manually.
2.6 LCD Contrast Control
To change the LCD screen’s contrast, press and hold the [RIGHT ARROW] key next to the
LCD screen (item 14 in Figure 1). The screen contrast will increase until it reaches the darkest
setting. Then it will return to the lightest setting and begin increasing the contrast again.
Release the [RIGHT ARROW] key when the desired contrast level has been reached.
The MCCB-250 will store the current LCD setting in non-volatile memory.
NOTE
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3.0 OPERATING PROCEDURES
3.1 Testing the Time Delay of a Protection Relay
Figure 3 illustrates a typical connection of the MCCB-250 to a protection relay to test its “Open
Time Delay”. The MCCB-250 injects a test current through a bus. The test current is sensed by
the CT of the protection relay. One of the relay dry contacts is used to stop the MCCB-250
timer.
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Figure 3. Typical MCCB-250 Application
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MCCB-250 USER’S MANUAL REV 2
Use the steps below to test the time delay of a protection relay:
a. Connect the Safety Ground to the MCCB-250.
b. Connect the AC power cord.
c. Connect the Current Cables from the MCCB-250 to the bus as shown in Figure 3.
d. Connect the [TIMER STOP] cables as shown in Figure 3.
e. Turn the [CURRENT CONTROL] knob to zero.
f. Turn on the [POWER SWITCH].
g. Select the DRY CONTACT mode for the [TIMER STOP] input by pressing the [LEFT
ARROW]
key until the DRY CONTACT LED light is illuminated.
h. Hold the [DOWN ARROW] key to momentarily turn on the current source. Note that
the HIGH CURRENT PRESENT LED will be illuminated.
i. Turn the [CURRENT CONTROL] knob to set the desired current.
j. Release the
k. Press the
[DOWN ARROW] key.
[UP ARROW] key to select the ON+TIMER mode and start the test. The
MCCB-250 will inject the preset current into the bus and turn on the timer. The timer
will stop and the current source will be turned off when the MCCB-250 [TIMER STOP]
input detects a change in the relay dry contact. A typical MCCB-250 time delay test
results screen is shown below:
986 mS 59.2CY
Ext I:+0.000 A
Drv I:20.00A
In the above test, the timer will be stopped and the current source turned off
by a change of state in the [TIMER STOP] input or when the operator
NOTE
presses the [DOWN ARROW] key to select the OFF mode. If the test is
aborted by the operator, no timer or current information is displayed.
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3.2 Measuring Current Transformer Primary and Secondary Currents
Figure 4 shows a typical connection of the MCCB-250 to a current transformer. In this
configuration, the MCCB-250 injects a test current through the CT primary. The CT secondary
current is sensed by the MCCB-250’s
[EXT CURRENT] input.
Figure 4. Typical Current Transformer Current Ratio Test Connections
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Follow the steps below to measure the CT primary and secondary currents:
a. Connect the Safety Ground to the MCCB-250.
b. Connect the Current cables from the MCCB-250 to the bus (CT primary) as shown in
Figure 4.
c. Connect the CT secondary winding to the MCCB-250 [EXT CURRENT] input as shown
in Figure 4.
d. Turn the [CURRENT CONTROL] knob to zero.
e. Turn on the [POWER SWITCH].
f. Hold the [DOWN ARROW] key to momentarily turn on the current source.
g. Turn the [CURRENT CONTROL] knob to set the desired current.
h. Release the [DOWN ARROW] key.
i. Press the [UP ARROW] key to select the ON+TIMER mode and to start the test.
j. Observe and record the CT primary and secondary current and the polarity displayed on
the LCD screen. A typical LCD screen display is shown below:
986 mS 59.2CY
Ext I:-1.004 A
Drv I:20.00A
The external current polarity is shown as in phase (“+” sign) or out of phase
(“-”) with respect to the MCCB-250 drive current. The CT turns ratio can be
NOTE
k. Turn off the current source by pressing the [DOWN ARROW] key.
obtained by taking the current ratio.
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1520 S. Hellman Ave • Ontario, CA 91761 • USA
Phone: 909-923-9390 • Fax: 909-923-9391
www.vanguard-instruments.com
Copyright © 2009 by Vanguard Instruments Company, Inc.
MCCB-250 User’s Manual • Revision 2 • September 15, 2009 • TA
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