Atec MS-2A User Manual

MS-2A

Circuit Breaker and Overcurrent Relay Test Set

MS-2A

Circuit Breaker and Overcurrent Relay Test Set

n

Light Weight, Portable Primary Injection
Test Instrument

n

Overcurrent Relay Testing

n

Ground Fault Performance Testing
for NEC 230.95

n

Circuit Breaker Testing

DESCRIPTION

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

ganizations.

Model MS-2A 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, ground-fault trip devices and overcurrent relays.

APPLICATIONS

Model MS-2A is capable of testing the time-delay
characteristics of over

current relays, 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.

The MS-2A is ideal for testing ground fault protection
devises with window CT’s. The NEC 230.95C requires
specific ground fault devices be performance tested when
initially installed.

The MS-2A is commonly used by many utilities and service
organizations as a economical light weight overcurrent
relay test system.

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

FEATURES AND BENEFITS

n

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

n

Digital memory ammeter: High-accuracy, direct­reading instrument has read-and-hold memory for
measurement of short-duration currents. Ideal for testing
ground fault devices, overcurrent relays and molded
case circuit breakers.

n

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

n

High-current output: Provides instantaneous currents
up to 750 amperes through a 125 ampere breaker in a
small 33lb (15kg) package

SPECIFICATIONS

Input

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

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.

Circuit Breaker and Overcurrent Relay T

MS-2A

est Set

Output Capacity: The output circuit is designed to permit short­duration 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.
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

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

1

3

/

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

2

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
±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
ener

gized 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 auxiliary
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 normally closed
contacts. The timer stops and the output is de-energized when the
contacts open.
Normally Open: Used to test a device with normally 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.

Standards

CE
EN 61326-2-1
EN 61010-1
EN 61010-031

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)

ORDERING INFORMATION

Item (Qty) Cat. No.

Model MS-2A

115 volt input MS-2A-115

230 volt input MS-2A-230

Included Accessories

Test Lead, red, 200cm, [2] 620143

Test Lead, black, 200cm [2] 620144

Alligator clip, red, [2] 684006

Alligator clip, black, [2] 684007

UK

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

UNITED STATES

4271 Bronze Way
Dallas TX 75237-1019 USA
T 800 723 2861 (USA only)
T [phone]
F [phone]
[e-mail]

Item (Qty) Cat. No.

Test and maintenance record cards

Green [50] 2239

Buff [50] 2238

No. 2 high-current leads, 2 ft (0.6 m) [2] 620155

Fuses

0.125 A, 250 V, MDL [5] 981

Instruction manual [1] 750026

OTHER TECHNICAL SALES OFFICES

Täby SWEDEN, Norristown USA,
Sydney AUSTRALIA,
Toronto CANADA, Trappes FRANCE,
Kingdom of BAHRAIN, Mumbai INDIA
Johannesburg SOUTH AFRICA
Chonburi THAILAND

ISO STATEMENT

Registered to ISO 9001:2000 Cert. no. 10006.02

MS2A_DS_en_V01

www.megger.com
Megger is a registered trademark