On 12/31/2015 10:24 PM, John Thornton wrote:
> I went and checked the control transformer and one side is 48v to ground
> and the other side is 79v to ground. I guess I was confused by that.
I did a quick calculation and if your protective ground has a voltage
with a phase shift of about 62 degrees wrt. the transformer's output and
the open voltage of the transformer is 132V, then one lead will show 48V
(RMS)(*) and the other will show 80V (RMS) with respect to ground.
>From this we can conclude that you are measuring a capacitive coupling.
Calculated from:
Ground potential : V * sin(a + p)
Transformer out A: V * sin(a)
Transformer out B: V * sin(-a)
with: a = running angle
p = phase shift
V = Voltage
Transformer output A wrt. ground:
V * RMS(sin(a) - sin(a + p))
Transformer output B wrt. ground:
V * RMS(sin(-a) - sin(a + p))
(*) I assume that your multimeter is measuring root-mean-square (RMS)
voltage in AC mode. That should be a pretty safe assumption.
--
Greetings Bertho
(disclaimers are disclaimed)
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