Electric motor brake

Technical specifications of the electric motor brake

The geometric shape of electric motor brakes is circular and its operation is based on electromagnetic force. The way the dynamo brake works is that two discs, a fixed disc and a moving disc, which are connected to the electric motor shaft, when the electric current is connected, the magnetic force generated attracts the brake pads (the fixed part of the brake) to the rear. And after cutting off the current with the help of traction force, the spring behind the pads is connected to the moving part of the brake and prevents it from moving.

Types of electric motor brakes in terms of power supply

The electric motor brake, which is one of the spare parts and accessories of the electric motor , is divided into the following categories in terms of power supply and current:

• Single-phase DC electric motor brake
• Single-phase AC electric motor brake
• Three-phase AC electric motor brake

The DC brake of the electric motor works with 24 volt electricity and the AC brake of the electric motor works with 220 volt single-phase electricity and three-phase electricity.

DC motor electric brake

Types of DC motor brakes include the following:

• Dynamic electromotor DC brake
• DC electric motor brake (reverse current electric motor brake)
• DC brake regenerative electromotor

Dynamic braking or direct current

In all types of DC shunt motors, the armature is disconnected from the power supply and a rheostat (variable resistance) is connected across it. The field coil is connected through the power supply. Obviously, the armature is driven by inertia and hence the motor starts. The braking effect is controlled by changing the resistance connected across the armature. 

Electric brake or reverse flow

In the case of a series DC motor, the motor is disconnected from the power supply and the field connections are reversed and a rheostat is connected in series. The field connections are reversed to ensure that current flows through the field coil in the same direction as before. In this method, the armature connections are reversed and hence the motor tends to run in the opposite direction. Due to the reversal of the armature terminals, the applied voltage V and the back EMF Eb start working in the same direction and hence the total armature current increases. To limit this armature current, a variable resistor is connected across the armature. This method is generally used in controlling elevators, machine tools, printing machines, etc.

Regenerative braking

Regenerative braking is used in cases where the motor load has very high inertia (for example, in electric trains). When the voltage applied to the motor is less than Emf, the reverse Eb decreases, obviously the armature current Ia reverses and hence the armature torque reverses. So the speed is reduced. Since the emf produced is greater than the applied voltage (the machine acts as a DC generator), power is returned to the line. This process is called as regeneration. As the speed decreases, the EMF Eb also falls back until it becomes less than the applied voltage and the direction of the armature current is again opposite to Eb.

Mechanical types of electromotor brakes

Types of dynamo brakes are mechanically divided into the following two categories:

• Single pad electric motor brake
• Double pad electric motor brake

Some types of dynamo brakes have the ability to install an inverter. This action causes a step start for the electric motor. Single pad brakes are routinely used for electric motors up to 4 kW. For the electric motor with more power, two-pad brakes are used. Also, in order to increase the value of the safety factor in powers less than 4 kilowatts, two-pad dynamo brake is used.

Electric motor brake components

Electromotor magnet, diode and electromotor brake coil are the main components of electric motor brake. The electromotor brake coil is a piece of copper wire that converts the magnetic field into electric current or vice versa.

Another part is the electromotor magnet. The function of the electromotor brake magnet is that when the electric current is connected, as mentioned, the electric force is converted into a magnetic force by the electromotor brake coil and releases the brake rigid part, which is the cause of the non-movement of the electromotor shaft. After cutting off the current by force, the compressed spring of the rigid part is connected to the shaft of the electric motor and prevents its movement.

Application of electric motor brake

Usually, in sensitive activities where it is necessary to stop the system in a fraction of time after the current is cut off, it is necessary to install a brake on the electric motor. For example, in the elevator when an accident occurs, there are sensors that cut off the current and the cabin stops with the dynamo brake function.

Electric motor brake price list

Sorry, all prices are being updated, please contact the sales department to inquire about the purchase price.