Dynamometer: How to choose a satisfactory dynamometer

1. In the testing of AC and DC motors and power tools, a dynamometer is often used as a testing device. The dynamometer mainly tests the torque, speed, and output power of the motor. However, not every dynamometer can meet all motor testing requirements, mainly considering three factors:Power dynamometerNot every dynamometer can meet all motor testing requirements, mainly considering three factors:

1. Torque testing range, the torque of the dynamometer usually cannot exceed a certain maximum torque value.

2. Speed testing range, the speed of the dynamometer usually cannot exceed a certain maximum speed. If used at excessive speeds for a long time, it will greatly shorten the lifespan of the dynamometer, especially due to mechanical wear.

3. The power marked on the dynamometer usually refers to the power that the dynamometer can absorb, as general dynamometers (hysteresis, magnetic powder, eddy current dynamometers) rely on absorbing heat to achieve energy consumption, which is the output power of the tested AC or DC motor or power tool. Strictly speaking, this indicator should not be exceeded; otherwise, the dynamometer can easily be damaged due to heat dissipation issues.

2. When selecting a power dynamometer, it must not only meet the three main technical indicators of speed, torque, and power, but also check if it meets the specific testing requirements. Generally, motors need to test parameters such as no-load speed, no-load loss, and locked rotor torque, which also need to be considered!

3. When selecting a dynamometer, all testing data of the motor should be between 30% and 90% of the dynamometer's performance parameters. This is because the testing accuracy of the dynamometer is relatively guaranteed within this range.

4. The commonly used dynamometers can be classified as follows: hysteresis dynamometer, magnetic powder dynamometer, eddy current dynamometer, power dynamometer (DC and AC power dynamometers).

Dynamometers are ranked by the maximum speed they can achieve as follows: eddy current dynamometer, power dynamometer, hysteresis dynamometer, magnetic powder dynamometer;

(1) The eddy current dynamometer cannot lock the motor or power tool, but its upper speed limit is very high, usually 20000~30000 RPM; it can also achieve a large torque.

(2) The hysteresis dynamometer generally has a speed below 20000 RPM, but it can achieve locked rotor conditions, although the power is not very large; the torque is generally below 20 Nm.

(3) The magnetic powder dynamometer has a lower speed, usually 1500~5000 RPM, but it can achieve large torque, and the motor can also achieve locked rotor conditions.

5. The power dynamometer does not require water cooling, only air cooling is sufficient; the eddy current dynamometer, hysteresis dynamometer, and magnetic powder dynamometer require both water cooling and air cooling. Some small power hysteresis dynamometers do not require water cooling to meet testing requirements; during the use of the dynamometer, the cooling function must be turned on.