View Single Post
  #1   Spotlight this post!  
Unread 17-08-2010, 18:01
kamocat's Avatar
kamocat kamocat is offline
Test Engineer
AKA: Marshal Horn
FRC #3213 (Thunder Tech)
Team Role: Mentor
 
Join Date: May 2008
Rookie Year: 2008
Location: Tacoma
Posts: 894
kamocat is just really nicekamocat is just really nicekamocat is just really nicekamocat is just really nicekamocat is just really nice
Send a message via AIM to kamocat Send a message via MSN to kamocat
frequency range of AC clamp current meters

I was wondering if an AC clamp meter could be used to approximate the current through a motor using this method:

Using a PWM-based motor controller, set the duty cycle to 50%. On a Jaguar, this should yield a square wave at about 30kHz.
Now, put the current clamp around ONE of the motor leads, and take your reading.

Will the device give an accurate measurement of AC current? Could this value easily be converted to DC current?
My biggest concern is that this signal will be well out of the operating range for the current-clamp device, since most are made for 50-60hz.

For those of you that are wondering "won't the coils in the motor smooth out that AC to DC purely through inductance?", I've looked at the waveform from a Victor to a fisher price motor. There's definitely inductive ring, but the square wave is still very well defined.
__________________
-- Marshal Horn