FAULT
FIXER
™
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Challenge #3 ·
motors
Single-Phased
A 480V 3-phase pump motor won't start. Hit the button and it just
hums hard and trips the overloads
in a few seconds. Operator swears it ran fine yesterday.
① Run your checks
L1
L2
L3
FUSED
DISCONNECT
MOTOR
Line side
of the disconnect, all three legs
tap
Load side
of the disconnect, line-to-line
tap
Motor windings
, balance and shorts
tap
② Make the call
A.
The motor is shorted, replace it.
B.
Bad overload block, replace the overloads.
C.
Open fuse or connection on L2 between the disconnect and motor, it's single-phasing.
D.
Incoming utility problem, call the power company.
Hint
1 Credit
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