47
(14) After an accident current flows, do not use the switch without checking.
Investigate the cause of accident to remedy it, and also confirm that the equipment is free from damage ; then,
use the switch again. When a short circuit current flows, it is necessary to pay attention to the melting of contact
of the contactor, wire-breaking of the heater and change of tripping characteristic of thermal overload relay.
(15) When connecting a power condenser, do not connect it to the primary side of the starter.
The power condenser is connected to the secondary side of the starter or the terminals of the motor. Where the
power condenser is connected to the primary side of the starter and the circuit is phase failure due to one phase
fusing, a roundabout circuit is made up passing the power condenser and a voltage of about 50 to 60% of the
power source voltage is applied to the coil; this causes flapping of the contactor.
Fig. 43 Correct insertion of power condenser Fig. 44 Incorrect insertion of power condenser
(16) Do not remove the cover of thermal overload relay, or touch its internal mechanism.
As the thermal overload relay is strictly adjusted at the factory, be sure not to touch the internal mechanism.
(17) Do not set the current of thermal overload relay at a point higher than needed.
Even in case of motors with the same capacity (kW), the load current varies with the number of poles and types,
so that it is necessary to set correctly the adjusting knob to the motor current.
Do not raise the set value to prevent occasional operation. Since the occurrence of operation must be due to some
cause, first, investigate the cause and remedy it. Otherwise, there is a possibility that a major trouble may take
place.
(18) The thermal overload relay should not be reset when the power is left on.
It is necessary to reset the thermal overload relay after turning off the power source for safety. Resetting must
be made after the cause of trip is eliminated.
(19) For the wiring to the thermal overload relay, a wire with an appropriate diameter should be used.
If the wire is fine, the operating time becomes fast and if it is thick, the operating time, slow.
(20) Do not mount the starter and contactor upside down, or horizontally.
Firmly mount the starter and contactor to avoid operating failure or lowered breaking capacity. (see page 36)
(21) If the contactor closes in a flapping manner (a state where the contact or is not perfectly closed, but vibrates
greatly during closing), do not use the contactor continuously.
This will cause melting of contact, release failure, and other troubles. Investigate their causes and eliminate this
erroneous closing.
(22) Do not remove unnecessary contacts.
Their removal may result in a loss of balance of the mechanism and have an adverse effect on the performance
of the contactor. (Be sure to fully tighten the terminal screws.)
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