The principle and maintenance of magnetic powder dynamometers

　　Magnetic powder dynamometerIt consists of a stator, solid rotor, excitation coil, magnetic powder medium, support, base plate, etc. When current passes through the inner coil of the magnetic powder dynamometer, a magnetic field is generated, causing the internal magnetic powder to align along the magnetic field lines to form magnetic flux. The tension generated by the magnetic powder chain becomes the resistance that prevents the rotor from rotating, which is the load torque. The load torque can be changed by altering the excitation current.

　　The magnetic powder dynamometer is a braking dynamometer designed and manufactured based on the principle of magnetic powder torque technology. It is a torque machine that applies torque load to the tested motor and absorbs its power, and it is also a rotating torque-static torque converter. Speed sensors and torque sensors are installed on the magnetic powder dynamometer, and the speed and torque of the tested motor are converted into pulse signals and analog signals by the dynamometer, which are sent to the dynamometer controller for display. When the tested motor drives the magnetic powder dynamometer to rotate, all the power output by the motor is absorbed by the magnetic powder dynamometer and converted into thermal energy, dissipated through a radiator, external cooling fan, or water cooling.

　　During operation, the controller provides excitation current to the magnetic powder dynamometer. When the internal coil of the magnetic powder dynamometer is energized, a magnetic field is generated, causing the internal magnetic powder to align along the magnetic field lines to form magnetic flux. The tension generated by the magnetic powder chain becomes the resistance that prevents the rotor from rotating, which is the load torque. It is only related to the current applied by the controller to the dynamometer coil and is basically unrelated to the speed at which the tested motor drives the dynamometer to rotate.

　　Common faults and maintenance methods for magnetic powder dynamometers:

　　1. When the electric soldering iron falls off and cannot form a closed circuit with the circuit, re-solder the copper winding joint of the magnetic powder dynamometer and the clutch.

　　2. If the copper winding of the magnetic powder dynamometer and the clutch is short-circuited and burned out, it is necessary to rewire the winding and keep a record, or replace it with a new winding.

　　3. Causes and solutions for excessive temperature rise and damage of the magnetic powder dynamometer and clutch;

　　1. Poor lubrication of bearings and jamming. Clean the bearings and inject high-temperature grease or replace with the same type of bearings.

　　2. Open circuit or short circuit occurs inside the winding. Carefully check the winding, identify the problem, and perform corresponding maintenance;

　　3. Uneven pressure of fixed screws causes the magnetic powder brake to deviate. Re-tighten the screws to ensure even pressure, allowing the brake to operate smoothly;

　　4. Overweight materials overload the linkage shaft roller. Reduce the load and lubricate the moving mechanism.

　　4. Causes and solutions for abnormal noises during the operation of the magnetic powder dynamometer and clutch;

　　1. The magnetic powder disk has scratches or the bearings are not operating properly. Carefully check for scratches in the disk, analyze the cause, and eliminate it; if the bearings are not operating properly, clean or replace with the same type of bearings. The magnetic powder brake is prone to problems during operation, so regular maintenance is recommended, lubricating the moving mechanism to ensure smooth operation.

　　2. Magnetic powder particles adhere to moisture or mix with foreign objects. Remove the magnetic powder and dry it.