Amp rating of current meters 2

[Mbrooke]

Do analog amp meters have a current limitation?

Basically I want to monitor leakage current on a 3 wire system. A, B, C meters 0-2000 amps, Ground meter 0-30 amps, possibly 0-5 amps range.

Question is, what if I get a persistent ground fault over 30 amps? Will my meter burn up? How will the burden of each meter effect the others under normal and GF conditions?

 

[waross]

A forward biassed diode will block about 0.7 Volts before it conducts.
I have seen motor control circuits where back to back, reverse biassed diodes were connected across the ammeter to protect the meter from motor starting overcurrent.
An ammeter has a very low voltage drop.
One or more diodes in series may be selected so that when the voltage across the meter rises to the forward conduction voltage the diodes conduct and prevent a further rise in the current, thereby protecting the meter.
Question: Has anyone seen this in practice?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Mbrooke]

Anyone know of any good digital meters that they would recommend? I am willing to look into them.