AC variable speed drive
hoist gantry crane applications;
Gantry crane is used to lift, lower and carrying heavy loads, and make heavy horizontal movement within a certain distance of lifting, handling equipment, in the production process has important applications.
Traditional methods such as
overhead gantry crane governor: string wound rotor induction motor rotor resistance speed, stator voltage thyristor speed control and cascade control, etc., their common drawback is wound rotor induction motor with slip rings and electric brush, requiring regular maintenance by the collector ring and brush caused the failure is more common, along with a large number of relays, contactors are used, resulting in a large amount of on-site maintenance, speed control system failure rate is high, and speed control system comprehensive technical indicators are worse, has been unable to meet the special requirements of industrial production.
AC variable speed drive has the following characteristics:
A. You can make ordinary asynchronous motor stepless speed regulation.
B. start current, reducing the power equipment capacity.
C. Smooth start to eliminate mechanical impact, protecting mechanical equipment.
D. The motor has a protective function, reduce the maintenance costs of the motor.
E. has significant energy-saving effect.
Since AC variable speed drive technology with the above characteristics, has begun to replace the DC speeder become the development direction of modern electrical drive its governor principle is as follows:bridge gantry crane From the three-phase AC power input to the inverter, after converting rectifier DC, and then by electronic switching circuit is converted to frequency and voltage three-phase alternating current can be adjusted, and the filtered output, the input power as a motor.
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