Tecumseh AH5540E Service Handbook page 49

electrocution, always follow the manufacturer's procedures and safety rules when using
these devices.
Connect one lead of either the megger or Hi-Pot to the copper suction line. Connect the
other lead to one of the terminal pins.
Repeat this procedure for the two remaining terminal pins. If the instrument indicates any
resistance less than 2 megohms between any pin and the housing (copper suction line), a
ground fault exists.
WARNING! To avoid electric shock, electrocution, and terminal venting with ignition do not
energize a compressor that has a ground fault.
If a ground fault exists, keep the power off and replace the compressor. See "System
Cleanup and Compressor Replacement After Compressor Failure" on pages 83-86. If the
compressor is not replaced immediately, mark and red tag the compressor to indicate
there is a ground fault. Do not reconnect the power leads. Tape and insulate each power
lead separately.
If a ground fault does not exist, leave the power off and all external components discon-
nected from the terminal pins. Check for continuity and proper resistance using the pro-
cedure on page 42.
Why use a megger or Hi-Pot?
Tecumseh Products Company recommends checking
for a ground fault only with a megger or Hi-Pot. A
conventional ohmmeter will not reliably detect a ground
fault under certain circumstances.
A megger is a special type of ohmmeter that is capable of
measuring very high resistances by using high voltages.
A Hi-Pot is a device that uses high voltages to measure
the flow of current across the insulation. Unlike an
ohmmeter, even one that can measure millions of ohms,
a megger or a Hi-Pot can detect a breakdown in motor
winding insulation before the motor fails.
WARNING! To reduce the risk of electrocution, always
follow the manufacturers' procedures and safety rules.
FIGURE 4-1: Top: Amprobe megohmmeter (commonly referred to as a "megger").
(Photo courtesy of Amprobe.) Bottom: A Slaughter Hi-Potential Ground Tester
(commonly referred to as a "Hi-Pot"). (Photo courtesy of Slaughter.)
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