a. Motor can be restarted if the initial start fails. Three attempts are
permissible when the motor is at ambient (cold) temperature. Two starts in
succession are permitted when motor is at normal running temperature.
Smaller motors have a more frequent starting cycle.
b. Should an additional start be necessary beyond the conditions stated above,
the following restrictions should be noted:
i. Let the motor cool down for 60 minutes before a full load restart.
ii. Let the motor cool down for 30 minutes before a no load restart.
iii. Two inching starts can be regarded as one normal start.
c. If the motor rotor fails to start turning after two seconds, shut off power
supply immediately. This can result from:
i. Too low a voltage at the motor terminals.
ii. The load is too large for motor rating.
iii. The load has seized mechanically.
iv. Electrical connections incorrect.
v. Single phase power has been applied.
vi. Any combination of the above.
Note – Investigate thoroughly and take corrective action before attempting a
restart.
4.2.3. Direction of Rotation.
a. Motors are generally bi-directional. Some 2 pole and low noise motors are
uni directional only. If motor is uni-directional the fan cowl will be fitted with
a direction of rotation arrow.
b. If direction of rotation must be changed on a bi-directional motor, cut
power and wait until the motor stops, then interchange any two of the three
incoming phase leads.
4.2.4. Power Supply. Voltage/Current.
a. Check if the voltage and frequency of the power supply are identical to that
shown on the nameplate.
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