Taps on the internal transformers?

[Bob Quinn]

I was reading the threads about rewiring the transformers to boost the shore power.
Is there only one option for a 10% boost or are there multiple taps available.

I'm only getting 180 Volts from my shore power. If only 10% is available that would get me 198, but that still is no where near correct.

I might need a deck transformer after all grrrr.

It hasn't been a "noticeable" issue, but I do often pop the breaker on my salon AC.

Today I fired up the genny to see if it made a difference. OMG the air actually blows. So now I can see how bad it was struggling, and probably frying the motors.

 

[luckydave215]

Yes, you need to do something about it.

Not all the transformers installed in our boats have optional tabs (mine don't) and the only recourse is an in-line transformer as I'm using.

 

[SKYCHENEY]

Its a 15% boost. That's what is available on these Jefferson electric transformers

 

[SKYCHENEY]

Yes, you need to do something about it.

Not all the transformers installed in our boats have optional tabs (mine don't) and the only recourse is an in-line transformer as I'm using.

I doubt that. My friends 1978 60C has the boost switches on his original transformers. Most electricians would tell you its not possible because they don't know that the primary and secondary must be swapped to make it happen. I would bet you just got the wrong information.

 

[Bob Quinn]

Its a 15% boost. That's what is available on these Jefferson electric transformers

Thanks Sky, I might just go that route. 15% is better than nothing. That will get me to 207 Hopefully it's enough to keep from smoking my ac's..

I don't know what "range" is acceptable for these things. I know they don't like 180V.

Thanks much

Just found this regarding Cruise Air units, not sure but looks like more modern units. "Should" be about the same acceptable range for the older units I would assume.

 

[Bob Quinn]

I have a little more info. Still a quirk.

I checked power at the pole. The low voltage legs I get 120V each.
The high voltage leg I see 208.

Checking at the end of my 50amp cable, the end that connects to the boat I am getting 118V, 120 V
and 208V

At my panel I'm still reading 180V (on the panel gauge), when the generator is running I read 225V and everything, including stove top, microwave and AC seem to work better.

I just asked the dock manager and he said the incoming power is in fact 208 3phase which explains the incoming voltages.

So as I see it I have a few possibilities going on:
1) the gauge on the panel is inaccurate and reading low (i.e. showing 180 vs 208) but that would mean when the generator is running and it shows 225, that the generator would be actually putting out approximately 260V, so I am suspect that is not the case.

2) I have some sort of voltage drop between the cord and the rest of the system. I did try switching from my shore power 2 input to shore power one input and get the same reading on the internal panel gauge (180-190) it seemed to up to 190 on shore power 1 input but that could just be fluctuation in the incoming voltage, I don't know.

3) could the internal transformed be tapped to step down power?

I think I'll pull the panel and get a reading on the incoming power with my meter. (it's a decent Klein so it should be fairly accurate)

I'm still leaning toward setting the transformers to boost, but don't understand the voltage drop I am seeing. Grrrrrr.


**** Update ****
I pulled the cover off the power panel for the AC units and measured voltages right at the breakers.
I have 198.5V
Still stumped as to the voltage drop between the outside cable and inside.

Maybe it's time to crack open those transformers and see if they are for some reason wired as step down.