Hitachi C 12FSA, Technical Data And Service Manual

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3 Soft start circuit
When the switch is turned on, the soft start circuit
functions to gradually increase the voltage applied to
the motor, thereby gradually increasing motor rotation
speed.
4 Constant speed control circuit
The constant speed control circuit receives signals from the rotation speed detector, and adjusts the amount
of voltage applied to the motor to keep the rotation speed of the motor as close as possible to a
predetermined value.
5 Overload protection circuit
When an overload sensor detects a motor load current that exceeds the maximum load limit of the
polyethylene V-belt, the overload protection circuit generates a command to cut off the power supplied to
the motor. This circuit is also effective in preventing the motor and the phase control element from being
damaged.
(3) Motor characteristics during electronic control
Fig. 26
Fig. 27
Voltage applied to
motor is gradually
increased.
Time
Switch ON
Rotation speed
Load current (A)