Loading a wiper motor for EMC testing 1

[SPIGUY1]

We are trying to develop a load for a wiper motor being tested for radiated emmissions and susceptibility. Presently we use a full size windshield upon which a layer of taclum power is applied to simiulate worst case friction. The wiper motor drives the wiper across the window to its full travel. This configuration is unweildy and can be dangerous due to the high torque load of the wiper motor (starting torque 130N-m)bouncing the windshield fixture off the lab floor. Is there a way to load this motor with a brake or variable torque motor to simulate a nominal torque of 10Nm with a current draw of six amps?

 

[Skogsgurra]

The easy way is to couple the motor to another motor (same as the one you are testing) and use a DC power supply in constant current mode (current limited) so the second motor acts as a brake. Set the current a little bit below the six amps that the motor under test shall draw. Friction will make the total load just right.

There is one problem with this set up - if you need to measure conducted AND emitted emission, you need to screen the braking motor well. And also use an isolating coupling.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[SPIGUY1]

Skogsgurra,

Thanks for your suggestation. We need to measure both radiated and conducted emissions, so we are looking now at a magnetic particle brake. Are these brakes reversible?

 

[itsmoked]

Just use an adjustable clutch. This test is only going to run for a minute. Let it heat up. It doesn't matter.

Keith Cress
kcress -

http://www.flaminsystems.com