a. Open the starter main dis c on nect switch and follow loc k o ut/tagout rules.
b. With the tester connect ed to the motor leads, take 10- s e cond and 60-second mego hm
readings as fol lows:
6-Lead Motor — Ti e all 6 leads together and te st between the l ead group and ground.
Next tie leads in pairs, 1 and 4, 2 and 5, and 3 and 6. Test betwee n eac h pair while
grounding the third pair .
3-Lead Motor — Tie termina ls 1, 2, and 3 together and tes t between the group and
ground.
c. Divide the 60-second r es is t ance reading by the 10-sec o nd reading. The ratio, or
polarization index, mu s t be one or higher. Both the 10- and 60-second r ea dings must be
at least 50 megohms.
If the readings on a field - ins t alled starter are unsat is f actory, repeat the test at the motor
with the power leads discon nected. Satisfactory re adi ngs in this second test indicat e the
fault is in the power leads.
CAUTION CAUTION
!
If the motor starter is a solid-state start e r, the motor leads must be disconnected
from the starter before an insulation test is performed. The voltage generated
from the tester can damage the starter solid-state components.