Structure and composition of magnetic powder dynamometers

　　Magnetic Powder DynamometerIt consists of a load, coupler, sensor, mounting base, lifting mechanism, test cabinet, input power measuring instrument, dedicated load regulator, and temperature rise measuring instrument. Let's first take a look at the structure of the magnetic powder dynamometer.

　　Typically, the load is composed of a magnetic powder brake. A magnetic powder brake is a rotating machine with a stator and rotor. Both the stator and rotor are made of magnetic conductive materials. The working gap between the stator and rotor is filled with magnetic powder. When the excitation current is applied to the excitation coil on the stator, the magnetic powder gathers to form a magnetic powder chain. Torque is transmitted through the magnetic bonding between the powders and the friction between the powders and the two moving parts. As the excitation current increases, the transmitted torque also increases. When the excitation current reaches a certain value, the magnetic conductive material becomes saturated, and the transmitted torque saturates. When the excitation current is interrupted, the magnetic powder loses its adhesion and becomes loose, thus essentially not transmitting torque. Before testing the magnetic powder brake, water supply must be provided first. After the test is completed, wait for the temperature to drop before stopping the water supply. The surface temperature of the yoke should be controlled at ≤ 85°C. If the temperature is too high, a blower should be used for cooling, or the inlet water temperature should be lowered.

　　Sensor: When the sensor is working, it converts the measured torque and speed into two sets of AC signals with a phase difference through two sets of magnetic electric signal generators on the elastic shaft. These two sets of AC signals have the same frequency and are proportional to the speed of the shaft. The change in phase difference is proportional to the measured torque. This sensor is a precision measuring instrument. It is strictly forbidden to strike it with a hammer. During the use of the magnetic powder dynamometer, excessive impact loads should be avoided as much as possible, which often occurs at the beginning or stopping of the test. Generally, it is during the moment of starting at low speed. During the shutdown process, it should not be stopped under load.

　　Installation of the lifting mechanism for the magnetic powder dynamometer: The mounting base uses a sand-cast base, low power, and bow-shaped steel material. The base is stable to avoid excessive vibration; otherwise, the data testing will be inaccurate.

　　Magnetic powder dynamometer test cabinet: Generally consists of a vertical cabinet, with control circuits, input power meter, output power meter, and dedicated load meter installed on the panel of the test cabinet. General operations can be completed on the panel of the test cabinet.

　　Note: It is normal for the magnetic powder dynamometer to sometimes freeze (usually during the startup process). Just turn off the power switch of the instrument and then restart it.