Continuous Current Motors with Composite Excitation

Compound excited electric motors are used where there is a need for constant speed with extreme load variations and in order to combine the best of the parallel connection with the best of the serial connection, for this there is the composite connection. We achieved optimum parallel engine speed regulation with the excellent starting torque of the series engine.         Browning 1VP68X

In general, we can say that depending on the application, DC drives have the greatest benefits in terms of reliability, user friendly operation and dynamic control, such as:

– operation in four quadrants with relatively lower costs;

– continuous cycle even at low speeds; high torque at start and low revs; wide variation of speed;

– ease in speed control;

– AC / DC converters require less space;

– flexibility (different types of excitation);

-relative simplicity of modern AC / DC converters.

The function of the composite motor is to make it possible to take advantage of the high torque of the series connection, without speed shots with reduced loads or no load, then apply the low speed variation of the parallel motor under different load situations.

 

The Soft-Starters

Soft-starter electronic equipment is the starting device for induction motors, all in a solid state, ie based on semiconductor switches. The principle of operation of the soft-starter is, like electromechanical systems, to reduce the initial starting voltage and how the torque is proportional to the current, and that to voltage, the electric motor will start with reduced torque. As a rule, the soft-starters have acceleration ramp adjustment. This adjustment can be done via potentiometer or HMI (Human Machine Interface). A5835 OLP

Static starters are microprocessor keys designed to accelerate or decelerate and protect three-phase induction motors and by setting the thyristor firing angle, we control the effective voltage applied to the motor. With correct adjustment of the variables, the torque and current are adequate to the needs of the load, ie, the required current will be the minimum required to accelerate the load without changes of frequency. Some features and advantages of the soft-starters are the setting of the starting voltage for a predefined time, the starting voltage pulse for loads with high starting torque, fast voltage reduction at an adjustable level, protection against phase overcurrent and undercurrent.