1. In order to facilitate speed regulation, the traditional crane trolley and trolley motor usually adopt winding motor, because its rotor is open circuit, it can be connected with the controller through the external resistance box to realize different speed switching, but such speed regulation can only realize stage speed regulation, and the rotor must be electrified through the contact of slip ring and carbon brush, so the use of carbon brush and slip ring wear degree, as well as the speed regulation resistance box are more maintenance parts, so it is not reliable to use;
2. Now the emergence of frequency converters, especially the emergence of lifting dedicated vector frequency converters, can replace slip rings, carbon brushes, resistance boxes, time relays, contactors and other external components, making the electronic control part of the external equipment greatly reduced, but the control becomes accurate Because the frequency converter can be adjusted at any time, it can achieve stepless speed regulation, the user's control is more simple and accurate, and many protection settings inside the frequency converter can provide comprehensive protection for the efficient and safe operation of the motor. The resistance can be adjusted to display the resistance value.
3. A resistance box is made up of several constant resistors of different resistance values, which are connected in a certain way. The constant resistance in the resistance box is generally wound with copper and manganese copper wire, so that the resistance value does not change with temperature.
