Atec Amp-MS-2 User Manual

MS-2

Circuit Breaker and Overload Relay Test Set

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Digital memory ammeter

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Digital, multirange timer

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High-current output

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Solid-state output initiate circuit

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Portable, high-current test set

MS-2

Circuit Breaker and Overload Relay Test Set

DESCRIPTION

The MS-2 test set is used around the world by several
thousand utility companies, industrial plants and electrical
service organizations.

Using the latest technology, Model MS-2 is a self-contained
test set that incorporates a variable high-current output and
appropriate control circuitry and instrumentation for testing
thermal, magnetic or solid-state motor overload relays;
molded-case circuit breakers; and ground-fault trip devices.

APPLICATIONS

Model MS-2 is capable of testing the time-delay
characteristics of motor overload relays and molded-case
circuit breakers rated up to 125 amperes, when following
the recommended test procedure of testing the time delay
of these devices at three times their rating.

Higher currents are available for the short durations
required to test an instantaneous trip element. For
example, the test set will provide a maximum short­duration output of 750 amperes through a typical,
125 ampere, molded-case circuit breaker.

Additional applications include verifying the ratio of
current transformers and testing panelboard ammeters and
voltmeters.

FEATURES AND BENEFITS

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Digital memory ammeter: High-accuracy, direct­reading instrument has read-and-hold memory for
measurement of short-duration currents.

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Digital, multirange timer: Crystal-controlled, high­accuracy instrument with autoranging measures
operating time to 1 millisecond.

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High-current output: Provides instantaneous currents
up to 750 amperes through a 125 ampere breaker.

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Rugged and lightweight: Unit weighs only 33 lb (15
kg) and is tough enough to withstand daily field or plant
use.

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Solid-state output initiate circuit: Solid-state circuit
eliminates need for contact maintenance.

SPECIFICATIONS

Input

Input Voltage (specify one): 120 V OR 240 V, 50/60 Hz, 1f

Output

Output Ranges: The output is continuously adjustable in four
ranges to accommodate a variety of test-circuit impedances:
0 to 5 A at 120 V max.
0 to 25 A at 24 V max.
0 to 120 A at 6 V max.
0 to 240 A at 3 V max.
Output Capacity: The output circuit is designed to permit shor t­duration overloads and the output ranges will provide several
times their current rating, provided the output voltage is sufficient
to push the desired current through the impedance of the test
circuit.

MS-2

Circuit Breaker and Overload Relay Test Set

The test set is capable of testing the time-delay characteristics of
devices rated up to 125 A using a test current of three times their
rating (375 A). Additionally, to perform an instantaneous trip test,
it will provide 750 A through a typical, 125 A, molded-case circuit
breaker connected with the test leads provided with the test set.
Overload Capability: To increase use of the test set, it is
designed so that the current ratings may be exceeded for short
durations. Because the magnitude of the output current is
determined by the impedance of the load circuit, the voltage
rating must be sufficient to push the desired current through the
device under test and the connecting test leads.

Percent Rated Maximum Minimum

Current Time On Time Off

100 (1x) 30 min 30 min
200 (2x) 3 min 8 min
300 (3x) 30 s 4 min

400 (4x) 7 s 2 min
Output Initiate Circuit: The test set uses a solid-state output
initiating circuit. To increase reliability and eliminate contact
maintenance, this circuit uses a triac instead of a contactor to
initiate the output.
The initiating circuit provides momentary and maintained modes
to control output duration. The momentary mode is used
whenever the output is to be on for a short duration, such as
when performing instantaneous trip tests, or to avoid damage or
overheating of the device under test while setting the test current.
In the maintained mode, the output remains energized until
manually turned off or, when performing timing tests, until the
device under test operates — which both stops the timer and
de-energizes the output.

INSTRUMENTATION
Ammeter

Operating Modes (switch-selected)

Memory
Normal

Display

3

1

/

2

digit, extra-bright LED display with 0.3 in. (7.62mm) numerals

Ranges (switch-selected)

0 to 1.999/19.99/199.9/750 A

ContinousAccuracy (overall ammeter system)

±1% of reading, ±1 digit on three high ranges
Regulating: ±1% of range, ±1 digit on low range

Timer

Display

5-digit, extra-bright, LED display with 0.3 in. (7.62mm) numerals

Ranges (switch-selected)

0 to 99.999 s
0 to 999.99 s
0 to 99999 cycles

Accuracy

±0.005% of reading, ±1 digit

Timer Control Circuit

This circuit automatically starts the timer when the output is
energized and automatically stops the timer and de-energizes the
output when the device under test operates. This circuit
accommodates the following test conditions by simple switch
selection of the appropriate mode:
Current Actuated: Used to test a device that has no auxiliar y
contacts to monitor, such as a single-pole circuit breaker. The
timer stops when the output current is interrupted.
Normally Closed: Used to test a device with nor mally closed
contacts. The timer stops and the output is de-energized when the
contacts open.
Normally Open: Used to test a device with nor mally open
contacts. The timer stops and the output is de-energized when the
contacts close.

Enclosure

The test set is housed in a high strength, molded, suitcase-type
enclosure with carrying handle and removable cover. Storage
space is provided for test leads.

Dimensions

9.9 H x 14 W x 11 D in.
(25 H x 35 W x 28 D cm)

Weight

33 lb (15 kg)

Item (Qty) Cat. No.

Model MS-2
115 volt input MS-2-115
230 volt input MS-2-230

Included Accessories

Timer control circuit leads, 5 ft (1.5 m) [2] 1282
Test and maintenance record cards

Green [50] 2239
Buff [50] 2238

ORDERING INFORMATION

Item (Qty) Cat. No.

No. 4 high-current leads, 5 ft (1.5 m) [2] 2265
Fuses

5 A, 250 V, MDA [5] 952

0.125 A, 250 V, MDL [5] 981
10 A, 250 V, MDA [5] 984

0.0625 A, 250 V, MDL [5] 987

Instruction manual [1] 8470

UK

Archcliffe Road Dover
CT17 9EN England
T [phone]
F [phone]

UNITED STATES

4271 Bronze Way
Dallas TX75237-1088 USA
T 800 723 2861 (USA only)
T [phone]
F [phone]

OTHER TECHNICAL SALES OFFICES

Valley Forge USA, Toronto CANADA,
Mumbai INDIA, Trappes FRANCE,
Sydney AUSTRALIA, Madrid SPAIN
and the Kingdom of BAHRAIN.

Registered to ISO 9001:2000 Reg no. Q 09290
Registered to ISO 14001 Reg no. EMS 61597

MS2_DS_en_V10

www.megger.com
Megger is a registered trademark