Current Source
The MCCB-500's current source has 3 outputs: 4vac @ 500A, 14Vac @ 125A, and 70Vac @ 25A.

The current sources can output short-duration overload conditions. This feature is convenient for performing instantaneous trip tests of molded case circuit breakers, or testing the time delay characteristics of magnetic overload relays.
Test current is measured and displayed on a 128 x 64 pixel back-lit LCD screen that is clearly visible in direct sun light or low light levels.

Control switches are used to turn the current source on and off, select the timer stop input type (current mode, dry contact, or wet contact), and control the LCD contrast.
A "momentary" mode can turn on the current source, capturing the current reading and displaying the value on the LCD.

This feature can be used to set the test current and minimizes the possibility of overheating the device under test.
Test current is turned on at the zero crossing point using a solid state device for reliability and precision timing.

Built-in Current Meter
The MCCB-500 features a built-in current meter that displays the test current (100mA - 3000A). Current reading accuracy is: ±1% of reading, ±2 digits. Test results (current reading and time) are retained after performing a test so that the test results can be reviewed.

This is a convenient feature when used with the momentary mode to preset the test current to avoid overheating the circuit breaker.

Built-in Timer
The MCCB-500's built-in timer displays the test results in milliseconds and cycles.

The cycle time (50 or 60 Hz) is selectable by the user. Timer reading range is from 0.1 ms to 2 hours.

Timer resolution is 0.1 ms and the timer accuracy is ±0.1% of reading, ±0.1 ms.
Timer Start Mode: Timer can be started