Part 12470
Rev. 2 3/25/99
2. Connect one end of a high-current lead to one side of instantaneous element in
overload relay. Connect other end of this lead to the COMMON terminal of test set.
3. Connect one end of second high-current lead to other side of instantaneous element
in overload relay. Connect other end to the appropriate output terminal (see
SELECTION OF OUTPUT TERMINAL 4).
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 in MEMORY position.
8. Connect a pair of light leads (timer leads) from Normally Closed Contacts or
Normally Open Contacts of overload relay to binding posts of test set labeled
CONTACTS.
9. Select appropriate timer STOP MODE.
10. Select desired timer display mode and range.
11. Rotate OUTPUT CONTROL knob clockwise and momentarily press OUTPUT
MODE Switch in MOMENTARY and release. Observe current reading retained by
ammeter.
NOTE: If the relay utilizes a high impedance instantaneous element and the desired test
current cannot be reached, transfer output lead to the next higher voltage, lower
current terminal, and repeat Step 11.
12. Continue Step 11 until overload relay trips. Observe current reading retained on
ammeter. Timer indicates elapsed time of test in cycles or seconds.
NOTE: To avoid tripping error caused by interference of time delay element, allow thermal
element to cool; or in the case of magnetic overload relays, for the piston to reset.
13. Repeat test, starting with OUTPUT CONTROL knob at position just below trip
current of instantaneous element observed in Step 12.
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