To properly test motors a load must be simulated to verify motors torque and horse power capabilites.
Hysteresis brake (or mag particle brake on higher torque applications.)
Most testing is on smaller motors, so torques would be 70 in/lbs. or less.
Description of Operation
A drive motor to be tested is put in place and run. The system controller measures the actual torqued output of the motor and the speed based on a pre-set load condition applied by the hysteresis brake.
Reason for Selection of Mag-Particle
Unlike the magnetic particle units, the hysteresis brake has no drag except for the bearings so the actual applied load to the system is minimized. In higher torque applications where drag is not a problem a magnetic particle may be substituted; however, on smaller motor applications a hysteresis will give much better results. A hysteresis brake has no frictional contact between the driving and stationary internal members. The force (or drag) is transmitted strictly by the magnetic lines of flux.
Very fine wire or film may require hysteresis versus magnetic particle brakes. In many other applications they are interchangable; however, hysteresis brakes are usually more expensive and are normally used only when the drag of magnetic particle brakes becomes a problem.