Dynamic Braking Resistor
Electromotor have two lines of stand and brakes
The Brak topic is not much very important for engine, for example, the motor of an industrial fan may be rotating and then stand still for a minute after a power failure. But an elevator motor must stop at the exact point which reveals the importance of brake in electric motors.
There are generally three ways for brake of electromagnetic motors:
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- Injecting DC current and creating magnetic conditions of locked rotor mode.
- Appling reverse current and causing the reverse rotation of the magnetic field.
- Moving engine into generator mode and putting resistance for electrical discharge.
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The third method provides better control of the braking requirements and imposes less pressure on shafts, axles and engine.
This method is known in the industry as dynamic braking and the resistance used for the absorption of reciprocating energy is called DBR (Dynamic Braking Resistor).
This method used be previously considered only for engines with the ability of changing the generator mode, but today, by use of drive in engine control, and by using DBR resistors in DC Link of drive the use of this technique is applicable for most engines.
In dynamic brake, the method of brake power relates to the power of brake resistor, the higher the resistance’s power is, the used brake should have higher power and intensity
In modern methods which tend to variety of strength in braking mode, the DBR resistors are made with different taps and the required conditions of smart brake can be provided by changing taps during braking.
One of the major industries in which highly use this type of resistance is rail industry and Traction Motor.
The range and capacity if these resistors for suffering and resistance based on electro-motor power, the amount of rotational energy (inertia) on the motor shaft brake at the moment (which is bearing the weight and torque characteristics) and respiration (interval between brakes) according to the type of application, mined.
