Fusing a 250 W ZW Transformer

[kristo]

I purchased on ebay an Eaton Miniature Circuit Breaker 3amp (WMZS1C03) to fuse my 250 W ZW.  Does anybody know how it gets wired? 

[lionelsoni]

Put it in series with the ungrounded conductor from the 120-volt power source. 

The transformer's original power cord and plug were unpolarized.  If the plug has been replaced by a modern two-blade polarized one, the grounded-conductor blade is the bigger one.  If it was replaced by a modern three-pin plug, the grounded-conductor blade is the one that goes into the slot in the wall receptacle socket clockwise from the round equipment-ground pin.  A modern cord should have an almost invisible (but easy to feel) ridge molded into the grounded-conductor wire's insulation.  Of course, unless the plug and cord are molded together, there is no guarantee that the two were connected together properly.  If you have a modern plug with screw terminals, the grounded-conductor screw is plated with white metal, the ungrounded-conductor screw is bare brass, and the equipment-ground screw is probably colored green.

[kristo]

Thanks, Bob.

[NNJRailfan]

If I'm starting from scratch (i.e. cord has never been replaced) and I'm planning on replacing with a new cord with polarized plug, how do I know which wire in the transformer gets the polarized wire?

[lionelsoni]

It doesn't matter, unless you want the output voltages of multiple transformers with polarized plugs to be in-phase with each other when plugged into outlets that are in-phase with each other.

[TrainLarry]

Kristo,

A 3 amp circuit breaker is much too small for the ZW. Normally the breakers are rated at 10 amps.

The proper breaker is either a VW-22, a Z-22 or a ZW-232 available from        The Train Tender

 

Larry

 

[lionelsoni]

Larry, he was asking about a circuit breaker on the transformer's primary winding.  At 120 volts, his 3-ampere breaker would allow the transformer to draw 360 watts.

The ZW's secondary-winding circuit breaker should be rated at about 15 amperes, not 10:  "The 'ZW' transformer...can supply continuously 180 watts at 14 amperes."