Can you identify this transformer?

[MAC-A-TAC]

There is a possibility of the two in ( or primary)coils are out of phase with each other but that would cause your out (or secondary) voltage to be close or at 0Vac. A negative reading in an ac system really doesn’t make much sense. Have you measured your out voltage at the transfer red and blue terminals??

[Akapeterc]

It looks like my step down transformer

[boatpoker]

Originally Posted by weshoff

I supplied my electrician with the correct Ample Power Isolation transformer wiring diagram and he said he will install a jumper "from neutral to ground at the panel".

Don't let him do that.
Suggest you hire an ABYC Certified Marine Electrician.

[Zhyachts]

This is a rare toroidal type isolation transformer. IMHO far superior to the normal welding types - very efficient, cool and quiet. You are lucky to have one. https://en.wikipedia.org/wiki/Toroid...d_transformers


It has a double center tap allowing 110/120 shore power input or, by disconnecting jumpers W1 and W2 and adding jumper W3, allowing 220/240 shore power input.



With a properly wired isolation transformer there are never any "reverse polarity" problems. Shore power input wires can be connected to the transformer either way and work just fine.



Dfelsent is correct, your boat's "neutral" is floating resulting in the 60 volt reading to hull ground, probably between the hull ground and both the the yellow and white (L1 and L2) output wires. Pick one and properly connect it to hull ground. Problem solved.


The Ample diagram shows shore power ground (green) being brought aboard and it seems to be attached to some mysterious unidentified place. Written on the diagram is "Do not attach to ship's ground". So where? Well, there should be a shield between the primary and secondary winding's (often with a bare copper connecting wire), which is not shown on the diagram. This, plus the transformer case if metal (which should be isolated from the hull ground), should be the ONLY connections to the green shore power ground. Any internal short to the shield will trip the shore power breaker to protect the boat. This shield is important and I hope Ample included it.


Your photo shows a green jumper from the case (top of connector buss) to the third terminal from the top. However, no other wire is shown connected to this point.


NOTE: If you have a steel boat and a Marinco shore power connector be sure its automatic green wire to hull connection is defeated. Either electrically isolate the Marinco fitting from the hull or remove the grounding tab on the edge of the fitting that connects the green wire to the hull when the shore power cord is inserted. Shore power ground is not really ground and connecting to your hull means your hull is now grounding the whole marina. Good by zincs, and maybe boat!