Ammeter Theory of Operation - Printable Version
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Ammeter Theory of Operation - bikestuff - 10-06-2016
Gang,
Has anyone gone though and figured out how the ammeters above the dash work? One of mine works (kinda) and one is dead.
I am assuming that there is a sensor (either a shunt or a Hall effect sensor) near the transfer switch. I am not sure where to even start.
Has anyone replaced their meters with digital? or even found a replacement source for the analog meter if that turns out to be whats wrong.
Thanks,
bill
RE: Ammeter Theory of Operation - Richard - 10-06-2016
Mine is a hall effect, I see the hot leads pass through two coils.
An alternative idea if you have a progressive surge protection box is to remote mount the display panel where the ammeters are now.
The display cycles through voltage, amperage, and frequency continuously.
RE: Ammeter Theory of Operation - bikestuff - 10-06-2016
Richard, where are the coils? Under the breaker box in a metal can?
RE: Ammeter Theory of Operation - Richard - 10-06-2016
Look there and in the big breaker box in the back. It is not clear to me why opening the breaker on the AC circuits disables the ammeters.
RE: Ammeter Theory of Operation - bestgenman - 10-07-2016
The analog AC ammeters are current transformer driven, these are sometimes called "donuts". The CTs are located in the circuit breaker panel at the rear of the coach. The standard ratio for CTs is 5 amperes on the secondary with the primary varying depending on the current carried. For example, 100:5, one hundred amps on the wire in the center of the CT results in 5 amp on the small secondary leads. The meter is 5 ampere full scale and the face plate is respective of the primary CT ratio. Newell doesn't use the standard 5 amp secondary (at least not on 567) instead, it is an unknown ratio.
With all due respect Richard, i don't think they are Hall effect. When the main breaker is opened the current flow stops so the meters drop to zero.
I wanted to read KWs which required a complete meter change as well as CTs. I selected a Crompton digital product, changed the CTs, & used the voltmeter leads (which also originate in the panel and are fused). The "plexiglass" strip holding the analog meters needed to be replaced since this digital replaced four meters. It's not as convenient since scrolling is required the view the individual voltages and currents but it does display one voltage, an average current , & kilowatts in one of the scroll positions (all three). That was the objective.
RE: Ammeter Theory of Operation - Richard - 10-07-2016
My bad, I ran Hall effect and coils together in my little pea brain.
RE: Ammeter Theory of Operation - bestgenman - 10-07-2016
[attachment=4129]For those interested, here is a picture of the meter.
RE: Ammeter Theory of Operation - RussWhite - 10-07-2016
Not that anyone would, but one of the big no no's of electrical work is to NEVER open the secondary of a CT transformer. In other words, don't lift the wire from your ammeter with power applied to the coach. Russ EE
RE: Ammeter Theory of Operation - bikestuff - 10-07-2016
I bet that I WOULD do that! Thanks for the words of caution!
RE: Ammeter Theory of Operation - bikestuff - 10-07-2016
Gang,
I found the "donuts" in the bottom of the breaker box in the back of coach. They don't look like current transformers to me. More like an induction device like a hall sensor. They are little donuts that have the red and black heavy gauge wires running through them. Am I understanding this correctly?
The problem that I have is that the ammeters in coach don't work. My plan is to verify that the white/black and white red twisted pairs actually show up behind ammeters. If that is correct, I will replace both meters with ammeters that include their own coils with something like this and this. While I am at it, I may replace the volt meters for matching units.
Is this a good plan?
Gordon, I like your setup but would rather have two meters so that I can see L-1 and L-2 at same time.
Thanks!
bill