한미테크윈

Control System

Secondary Resistor Control System

FEATURE: The operating speed is determined at the point where the motor torque and the load torque match in the torque and speed characteristic curves.
Since the motor torque and the load torque are the same in the direction of the vertical motion, the operation is not ideal below the synchronous speed.

If the motor speed exceeds the synchronous speed, the motor becomes an induction generator and generates a torque that counteracts the load again to balance.
This means regenerative braking which converts the energy obtained by the load into electric power and returns it to the power source.

In this region, the larger the secondary resistance, the faster the equilibrium speed.
Therefore, in the minus load in the downward direction, the operation of the master controller must be quickly operated to the final notch to quickly short-circuit the secondary resistance.

For the above reasons, the secondary resistance control is generally applied to horizontal motion such as Travelling and Traversing without applying to vertical motion such as Main or Auxiliary Hoisting.

Circuit Diagram

① Simple speed control is possible.
② Applicable regardless of motor capacity.
③ Simple circuit configuration and easy maintenance.
④ Difficult to control of below synchronous speed.
⑤ The motor speed varies according to the load variation, and the speed variation is very large in the low speed range.

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