Home |
Search |
Today's Posts |
#20
posted to rec.boats.electronics
|
|||
|
|||
Isolation transformer and connection to ground
In article . net, chuck wrote:
Yes and no. The type of shield you are thinking about was indeed intended to reduce noise, and it typically was grounded on the side most likely to be noisy. The Faraday shields in those "non-marine" isolation transformers are designed to handle signal-level currents. My understanding of shields in general, is that the shield should be connected to the ground with the least noise. greg Marine-type isolation transformers (as contemplated by the ABYC) utilize shields designed to handle the full current rating of the transformer. Presumably the presence of that shield would cause primary leakage currents to flow through the shield to the shore grounding wire (thus tripping a GFCI breaker) rather than through the transformer core to the secondary. The shield is intended to provide belt and suspenders safety, rather than noise reduction, although it undoubtedly offers up some of that as well. Chuck Terry K wrote: As I recall from training many years ago, the shield is a noise remedy. It seems it should connect to the vessel's signal ground / counterpoise through a radio frequency capacitor, to cancel and block noise from the radio circuits, via the ship's neutral connector. The transformer case and frame should be connected to shoreside "Earth", and neutral at the power pole / entrance. This presumes that the shield is not connected to the frame of the transformer. If it were, I would try it both sides and disconnected, to satisfy noise and galvanic requirements while at the dock. |