Jiaozuo brake

Ms.'s friend sold two YEJ motors, and there were no abnormalities during the motor test, including the verification of the motor's braking effect. However, there was a fact that the motor could not start during user use. The service personnel arrived at the scene and found that there was a problem with the brake wiring. After reconnecting, everything was normal for the motor. In response to this issue, according to the opinions of service personnel, improvements have been made to the factory wiring of this type of motor, and similar problems have not occurred again.

About the power loss brake

Electromagnetic brake is a commonly used additional device for electric motors, which can be divided into two types: energized brake and deenergized brake. The electric braking method is fast and accurate in positioning, and is used for automated intelligent control equipment that requires precise positioning. Its application has certain limitations; Electromagnetic power loss brakes (hereinafter referred to as brakes) are widely used in mechanical transmission systems with positioning and braking requirements, such as machine tools, metallurgy, motors, chemicals, construction, packaging and printing, textiles, and automated production lines. In addition to the advantages of easy operation and fast braking speed, power loss brakes mean that equipment can safely brake in case of unexpected power outage and loss of control, ensuring the safety of personnel and facilities.

Structural advantages and characteristics

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

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

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

Working principle of braking

The electromagnetic power loss brake mainly consists of magnetic choke, armature, connecting plate, spring, friction disc, gear sleeve and other components equipped with coils. The spring is installed inside the magnetic choke, and the armature can move axially. The magnetic choke is fixed to the base by installation screws and the clearance is adjusted. After reaching the specified value, the gear sleeve is connected to the transmission shaft through a key, and the outer teeth of the gear sleeve mesh with the inner teeth of the friction plate. When the coil is powered off, under the action of spring force, friction is generated between the friction disc and the armature, the base (or connecting plate), and the transmission shaft is braked through the gear sleeve. When the coil is energized, under the action of electromagnetic force, the armature is attracted to the magnetic choke, causing the friction disc to release and release the brake.

Brake operating conditions

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

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

The brake is equipped with Class B insulation around it, with voltage fluctuations not exceeding+5% and -15% of the rated voltage. Its working mode is in accordance with the continuous working system installation control requirements.

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

Before installation, the brake must be cleaned thoroughly, and there must be no oil or dust on the friction surface and inside the brake.

The gear sleeve must be fixed axially.

Simple calculation principles for selection

The choice of brake model largely depends on the size of the required braking torque. In addition, factors such as inertia moment, relative speed, braking time, and operating frequency of braking should also be considered. The following are the design rules recommended by a certain brake manufacturer. Different manufacturers may have some differences, but the principles are all similar.

Calculate the required braking torque: T=K × nine thousand five hundred and fifty × P/n

Among them: T - Required braking torque (N.m)

P - Transmission power (kW)

N - Relative speed during brake braking (r/min)

K Factor of safety (K>2)

Maintenance and upkeep of brakes

After using the brake for a period of time, due to the wear of the friction parts, it is necessary to readjust the clearance value by adjusting screws, nuts, adjustment sleeves, etc. to meet the specified value.

The friction surface should always be kept clean and free of impurities.

Issues that must be noted during installation

The brake and motor share the same power supply, ensuring that both the motor and brake are powered on and powered off simultaneously.

Given the characteristics of both supplying power and losing power simultaneously, it is necessary to ensure consistency in the rated voltage of both.

The brake can only lose power and release the brake control at rated voltage. Once the voltage is low, the motor cannot start, and the motor will be burned out as a result; Therefore, the motor for installing the brake must ensure that it starts at full pressure.

For the short circuit test of the motor, due to the low pressure applied (such as 380V three-phase asynchronous motor, the pressure is generally 100V), it is not necessary to block the rotor to meet the static state requirements of the motor

The clearance of the brake disc is generally adjusted before leaving the factory. After the installation of the brake, the conformity of the clearance should be verified and judged through inspection and testing.

The brake wiring should be reliable, and its terminal should be installed under the motor's own wiring fixing nut together with the motor stator terminal to ensure that the customer's wiring will not affect its original wiring reliability. This is also the fact that Ms. Shen mentioned in the beginning of the article the measures to improve the brake wiring, which can be considered a catch up.

Fault Cause Analysis

The brake cannot be released after being powered on: possible reasons include coil damage; The power supply is not connected or the voltage is insufficient; The working gap is too large to close.

Insufficient braking torque of the brake: the motor speed is too high; Excessive motor load; Impurities or damage on the friction surface; Insufficient or ineffective spring force.

Brake heating: The friction plate slips due to overload; Insufficient supply voltage.