What is the function of DBR in Elevators?

 DBR

The basic property of resistors is the enormous power consumption and dissipation of the consumed energy in the form of heat. When a mechanical system slows down, the system acts as a generator, creating a large amount of electrical energy which is transferred to the power circuit. This large amount of energy is consumed by the resistance present in a circuit. the resistor converts the consumed energy into heat and at the same time creates a braking effect. Therefore, the resistor used in this is called a braking resistor and the process is called dynamic braking. Therefore, the purpose of a braking resistor is to quickly stop or slow down the mechanical system by producing braking torque.

 Braking resistors are designed with specifications such as resistance and average braking power. Braking resistors with lower ohmic values help motors stop faster and dissipate more heat. Brake resistors require less maintenance and offer greater reliability. Therefore, brake resistors are preferred over friction brakes for decelerating motors.

Speed control is very essential in elevators so the braking resistors are an integral part of it. Stopping an elevator is a two-step operation. The first step is to use regenerative braking to reduce the speed of the elevator. The second step is to use a separate electro-mechanical brake to stop the elevator. While decelerating, elevators allow the full load current to pass through the DBR, which dissipate the power as heat. The resistance value and the heat sink mechanism of the DBR are critical in the smooth operation of the elevator.

Main advantages of utilizing DBR

• Quick stop of AC and DC motors
• Prevent temperature rise at the moment of motor braking
• Maintain the voltage in the operating range of the motor and prevent inverter overvoltage trip
• Reduce the risk of mechanical braking failure due to temperature rise
• Reduce damages to the parts involved with the mechanical braking system.