Molded Case Circuit Breaker Tester AMCCB250


The AMCCB-250 is a programmable, high-current source designed specifically for testing molded-case circuit breakers as well as thermal, magnetic, or solid-state overload motor-protection relays.

Built-in Timer

The AMCCB-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 AMCCB-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 cycle(s) on the unit’s back-lit LCD screen (20 characters by 4 lines).

External Current Input

The AMCCB-250 also provides an external current input (0 – 10 A). Both internal and external current source readings can be viewed at the same time.

Current Source

The AMCCB-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 (1000 A max). 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.

AMCCB-250 Output Current and Duration Table


On time

Off time

100% (1x)

30 minutes

30 minutes

200% (2x)

3 minutes

5 minutes

300% (3x)

30 seconds

4 minutes

400% (4x)

4 seconds

7 minutes

Complete specifications table


250 Ampere current source

Physical specifications

17"W x 12K"H x 10K"D (42.6 cm x 32cm x 27 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

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


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


Designed to meet IEC61010 (1995), UL61010A-1, CSA-C22.2 standards


Operating: -10°C to +50°C (+15°F to +122°F); Storage: -30°C to +70°C (-22°F to +158°F)


90% RH @ 40°C (104°F) non-condensing


2,000 m (6,562 ft) to full safety specifications


Power cord, ground cable, 10-foot #2 AWG test leads


Transportation case


1 year on parts and labor

Controls Molded Case Circuit Breaker Tester AMCCB250Connections Molded Case Circuit Breaker Tester AMCCB250

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