Re: {Collins} Collins radios and ground fault circuit breaker tripping

On Aug 23, 2013, at 7:46 PM, lorenzenenterprises@xxxxxxxx wrote:

> ... the class A ( 5 mil trip )  ground fault breaker will trip off. ... The breaker is tripping off because of ground fault, not excessive current. 


I take is you have ground fault circuit breakers in your electrical panel, not GFI outlets in the wall.  (I think for the purposes at hand, it really doesn't matter.)

> This rigs have .01 capacitors connected from each end of the primary 120 volt winding to chassis ground.

That's the way they USTA do it.  Before GFI devices were here to protect us.

> I suspect that it is current flow through  these capacitors from line to ground which is causing the ground fault breaker to trip 

You are almost certainly right. There is a solution.

> It might also be leakage from the transformer primary winding to chassis causing the trip.  

Unlikely unless your radios and the transformers in them are VERY old.

> What is the purpose of the .01 capacitors - line to ground, at both ends of the transformer primary ?

To keep RF noise from the power lines out of the radio and to keep RF leakage from inside the radio getting out.

> ...if the capacitors are not needed - can they be disconnected, if they are causing the ground fault breaker to trip.?

Yes, it's likely that they can be taken out with no real problems for you or for anyone else.

> An isolation transformer is not the solution - isolation transformers have earned their reputations as widow - makers -

I'd be gad to hear more about this.  Can you tell me/us why they have this reputation?
> and an isolation transformer would block the ground fault protection.   . 

Not if there is a three wire outlet on it and the safety ground wire is connected to the input three wire safety ground.  That is, if the third pin on the outlet and the supply cord are connected.  I simply do not know if this is normal or not.

SOLUTION to the bypass cap GFI problem:

Get safety rated line bypass caps. 
 just has them and also has information about these caps and how they are normally used.

BUT - do not hook a cap from both sides of the line ("Line" and "Neutral") to the chassis.  Instead, put an X cap from Line to Neutral and a Y cap from Neutral to Chassis.  Hook the green wire from the three conductor line cord to the chassis.

You can see that there will be normal capacitive current from line to neutral.  The GFI device will detect this as normal, safe current.  There will be very low if any current through the cap from neutral to chassis (unbalanced current) because the voltage is normally a volt or two if that.

You, the radio, and the GFI device will be happy.


Roy Morgan
K1LKY Since 1958 - Keep 'em Glowing!

This archive was generated by a fusion of Pipermail (Mailman edition) and MHonArc.