Part 12470
Rev. 2 3/25/99
a. POWER ON/OFF Switch in OFF position. (instrument displays OFF)
b. OUTPUT CONTROL knob at minimum, `0' position.
c. OUTPUT MODE Switch in center OFF position.
2. Connect one end of high-current lead to one pole circuit breaker. Connect the other
end of this lead to the COMMON terminal of test set.
3. Connect one end of second high-current lead to the other side of the same pole of the
circuit breaker. Connect other end of this lead to the appropriate output terminal (see
SELECTION OF OUTPUT TERMINAL).
4. Connect test set to suitable single-phase power supply.
5. Turn test set on with POWER ON/OFF Switch (instrument displays should light).
6. Use RANGE Switch to select ammeter range so test current will be near full scale
and no less than 10% of full scale.
7. Put ammeter DISPLAY MODE Switch in MEMORY position.
8. Place timer STOP MODE Switch in CURRENT position.
9. Select desired timer display mode and range.
10. Rotate OUTPUT CONTROL knob clockwise and momentarily press OUTPUT
MODE Switch in MOMENTARY release. Observe current reading retained by
ammeter.
If desired test current is not reached with OUTPUT CONTROL knob at maximum
clockwise rotation, return knob to zero and transfer output lead to the next higher
voltage/lower current terminal. Proceed with current adjustment as in Step 10 (see
SELECTION OF OUTPUT TERMINAL).
11. Continue Step 10 until circuit breaker trips. Observe current reading retained by
ammeter. Timer indicates elapsed time of test in seconds or cycles.
NOTE: To avoid tripping error caused by time delay element over heating, allow time for it
to cool.
12. Repeat test, starting with OUTPUT CONTROL knob at position just below trip
current of instantaneous element observed in Step 11.
13. When circuit breaker trips, timer stops and output is de-energized. Current reading is
retained on ammeter. Timer indicates elapsed time in seconds or cycles.
14. Turn test set OFF with POWER ON/OFF Switch.
15. Record results.
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