Crane starting throttles

Our throttles are mainly used in electric drives of crane mechanisms, both for moving bridges and trolleys, and for lifting mechanisms.

When using such throttles, the control circuit of the stator circuit of the electric motor remains unchanged, and the throttleis included in the rotor circuit. The entire rotor circuit diagram is as in the pic. 1. When the throttle is turned on, the starting torque can be provided more than on the natural characteristic with a significant decrease in the starting current.

Throttles provide smooth starting and braking of the electric motor without shocks in the mechanism, with limitation of starting currents in case of no control system for the motor rotor, maintaining an approximate constancy of the torque up to a speed of 0.5-0.6 from synchronous.

The pic. 2 shows the mechanical characteristics of the throttle induction motor drive. The attribute 1 is a natural characteristic of the electric motor, the attribute 2 - when the throttle is switched on in the rotor circuit. It resembles a kind of "excavator" characteristics.

When controlling the mechanism of the crane electric drives by a direct-flow controller, a crane operator can work carelessly. The use of a throttle prevents the operator from operating the crane at the maximum-limit counter-modes.

As for a crane hoist mechanism, the use of a throttle makes it possible to form the required mechanical characteristics, with the exception of the landing speed of the mechanism, the mode of choosing the slack of the ropes at low landing speeds. The latter can be realized using a DRS thyristor speed controller of our production.

Advantages of our throttles:

• no relay-contact equipment (contactors) and starting-braking resistors in a circuit with an electric throttle drive;
• removing the current and torque peaks in the rotor and stator circuits of the electric motor increases the reliability and service life of the entire electric drive (switching equipment, etc.) by 4-6 times, as well as the components of the distribution devices of the power supply network;
• the reliability of the mechanical part of the crane is increased (shock loads in mechanical transmissions are reduced), which increases the service life of mechanical equipment (gearbox, etc.) by 2-4 times;
• energy consumption is reduced by 5-8%;
• it takes less time for the replacement and repair of control gear;
• the overhaul cycle of the mechanisms of hoisting machines increases;
• the time for repair and maintenance of the electric drive is reduced, especially in heavy duty conditions of mechanisms and aggressive environments (gas pollution, dustiness, high air temperature);
• during the installation of new cranes and reconstruction of old ones, the cost of electrical equipment and cable products is reduced by 50%, and installation work is reduced by 70%

Specifications