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arthur...
arthur...

Posted: Sun May 16, 2010 9:16pm

Post Subject: electrical

Hi Tony iam fitting a c.a.v.100 amp moving coil ammeter, can i use any 100 amp shunt with this meter? Thanks Arthur

Tony-B...
Tony-B...

Posted: Mon May 17, 2010 7:51am

Post Subject: electrical

The shunt must be rated to carry the maximum current likely so in this case it is probably 100 amps, as you say. However it also needs to cause a voltage drop of xxx when those 100amps are flowing. xxx is the milivolts required to give full scale deflection of the ammeter. So you need to know how many milivolts makes the meter show 100 amps. In fact you could use a 200 amp shunt as long as at 100 amps it produced the correct voltdrop. I have not been able to find the mV for a CAV meter with a quick Google so the only way I can think this could be done is to put it on a variable power supply with the voltage turned to zero and the gradually increased until the meter showed full scale deflection. Then read the mV off the supplies meter. I expect any secondary school or college will have them in their science department as may electronic equipment repairers. If there is a simpler way to do it I would be very grateful for a reader to add their comments. Tony Brooks

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