Mainly our reactors are used in electric drives of cranes: to power axles, carts and hoisting machinery.
When such reactors are used the motor's stator control circuit remains unchanged, while into the rotor circuit a reactor is introduced. In this case the design of the rotor circuit is as represented in Fig.1. When the reactor is switched on the value of the start moment can be greater than at a conventional characteristic while the starting amperage is significantly reduced.
The reactors ensure smooth start and braking of the motor, eliminate shocks in the machine, while reducing starting currents in absence of the rotor control system, keeping the moment relatively constant up to 0.5-0.6 of the synchronous rate of revolution.
The mechanical characteristics of the reactor induction motor drive are represented in Fig.2. Characteristic 1 is a conventional characteristic of a motor; Characteristic 2 is the one one the reactor is introduced into the rotor circuit. It resembles that of “an excavator” characteristic.
A reactor electric drive specifications
The crane operator can do anything (s)he pleases when the crane's electric drives are controlled through a co-current controller. The use of a reactor eliminates the possibility of the operator to operate the crane at maximum-permissible counter-modes.
The required mechanical characteristics can be formed through the use of the reactor, these characteristics but the load lowering speed and the cable-slack-hauling-in mode at low load-lowering speed. The latter can be achieved through the use of the DRS-series thyristor revolution-rate controller manufactured by our company.
Advantages of reactors manufactured by our company:
absence of relay-contact devices (contactors) and start-braking resistors in the reactor drive circuit;
eliminates peaks of both the current and the moment in the motor's rotor-stator circuits which results in lengthening the drive's lifetime and improving the drive's reliability (switching equipment etc.) 4-6-fold. The same improvement can be applied to complex elements of the power-supply grid's switching devices;
improvement in the reliability of the crane's mechanical parts (shock loads in gears are reduced) resulting in the mechanical parts' (reductor etc.) enhanced life-time 2-4-fold;
power saving by 5-8%;
Crane current-limiting reactors
shortening of the maintenance and replacement time of the starting/regulating devices;
lengthening od the inter-repair period of the hoisting machinery;
shortening of the servicing period, especially in cases of adverse working conditions (gas contamination, dustiness, high air temperature);
at the assembly of new cranes and redesigning of old ones the expenses on electric equipment and cables are cut by 50 % while the volume of the assembling work by 70%.
