Jiaozuo brake

Xiao L, who specializes in motor testing work, has one specialty: he is very sensitive to tedious test data. There is a batch of motors with brakes installed, and the short-circuit data is very consistent. Little L noticed some differences from the motors tested in the past, and asked Ms. why the parameters are so neat and uniform. Ms. Shen also felt that this phenomenon was somewhat strange and specifically understood the entire experimental process.

The original testing equipment used by XiaoL did not mechanically brake the motor when collecting short-circuit data, but only collected instantaneous values. Under normal conditions, there may be objective differences in the starting time of different motors after being powered on, resulting in poorer data consistency. Relatively speaking, there are two special characteristics of motors equipped with brakes: firstly, the voltage is lower during short-circuit testing; Secondly, when the motor is not in operation, the rotor is in a stationary state, so the consistency of the corresponding motor test data is better.

The power loss brake has been widely used as an additional device for motor products, due to its advantages of simple structure, low noise, safety and reliability, and is widely used in various mechanical transmission devices. Power loss brakes are a branch of brakes that have been well promoted in motor products due to their unique advantages.

Brief Description of Working Principle

When the excitation coil of the brake is connected to the rated voltage (DC), the electromagnetic force pulls on the armature to separate (release) the armature from the brake disc. At this time, the transmission shaft runs or starts normally with the brake disc. When the transmission system is separated or powered off, the brake is also powered off at the same time. At this time, the spring is applied to the armature, forcing Friction torque between both sides of the brake disc and the armature and the flange to stop the transmission shaft quickly. Because the brake is braking in a state of power loss, it is named after "power loss braking".

If the heat dissipation environment of the brake is poor and the transmission shaft operates continuously for a long time, if conditions permit, the voltage can be converted to 70% -80% of the rated voltage after the brake operates to reduce heat generation.

Line connection between power loss brake and motor

According to the actual needs of motor braking, the brake and motor share a wiring board to achieve simultaneous power supply and power outage. It is particularly important to emphasize that this type of brake can only be started with rated voltage, otherwise it may cause excessive short circuit current and motor burnout due to the inability of the brake to start. For the short-circuit test of three-phase asynchronous motors, there is no need to implement rotor blocking on the motor, as the brake cannot be released under low voltage conditions, which can ensure that the motor rotor is in a stationary state.

Precautions for brake installation

There must be no oil stains on both sides of the friction disc and the surface of the armature, and it must be kept clean, otherwise it may not be possible to achieve braking due to insufficient friction force;

Proper air gap must be ensured during installation“ δ”； To ensure the free suction and release of the armature, it is necessary to ensure an air gap“ δ” Suitable and uniform in size.

The gear sleeve must not have axial movement.

After installation, the hollow bolt must be screwed out and locked onto the rear cover or flange of the motor.

Brake structure and performance characteristics

The brake is composed of a magnetic yoke, excitation coil, spring, brake disc, armature, spline sleeve, installation screws, etc. The brake is installed at the rear end of the flange plate (or motor) of the equipment; The transmission shaft is connected to the spline sleeve and the brake disc.

1. Although the axial size of the compact and power-off brake is small, the braking torque is sufficient.

2. The quick response and power loss brake uses a spring device to form braking torque, and the spring reset time is the braking response time

3. Long service life, power loss braking adopts new friction materials, which determine the performance of long service life.

Suitable working conditions for brakes

1. The relative humidity of the surrounding air shall not exceed 85% (20 ± 5 ℃)

2. There is no gas or dust in the surrounding medium that is sufficient to corrode metals and damage insulation.

3. The brake is surrounded by Class B insulation, with voltage fluctuations not exceeding+5% and -15% of the rated voltage, and its working mode is continuous working

4. During installation, ensure the accuracy of the fit between the transmission shaft and the brake.

5. The brake disc of the brake must be used without oil stains.

The above unofficial content only represents personal opinions.