European Marina 220 v dock receptacles and step down transformers

[SV Enough]

Spoke to Charles electric about soft start and indeed yes soft start is called for. And as it would happen they now have a soft start device which I will use.

Also refurbished 7.5 KVA transformers are available directly from Charles, the soft start device can be obtained through Grainger.


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[Paul L]

Instead of one large isolation/stepdown transformer on the 32 amp side why not use two 3.6kva. One on each of the 120v/30amp circuits. Use the pigtail split to feed those from the 32 amp circuit. The transformers will be much more manageable in weight and size. That's how my system is setup.

[SV Enough]

The 93-IXFMR 3/8I-A is about 10 cubic inches at 70 pounds. So times 2 is 20 cubic inches and 140 lbs total. A pair of these is about $1200 +/-

The 93-IXFMR7/5T-A is about 12 cubic inches at 155 pounds, and that's it. A refurbished one of these is about $1200. +/-

NEITHER of these are trivial hunks of iron to to shlep around so some sort of permanent or semi-permanent mounting is called for somewhere. I could be wrong but I have my doubts most marinas will be enthusiastic about mounting either on their pier, leaving mounting aboard.

The twin 93-IXFMR 3/8I-A does have redundancy if one should fail. Does anyone have reliability information on failure rates for transformers used like this in general.

The twin has redundancy and the single takes up less space; it looks pretty much like a wash to me?

Am I missing anything?


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[Paul L]

The twin also acts as an isolation transformer when you use it on a dual 110 system, something that the single would not.

[SV Enough]

Actually the 93-IXFMR7/5T-A will fully isolate both 120 outputs from each other and the dock. There are 2 separate 2:1 secondaries with center tap 120-0-120 when used in step down. It can also be used as a 1:1 isolation if 240 v is needed but I have no 240 aboard.

http://www.charlesindustries.com/mar...ual/7.5kva.pdf

See figure 1 page 6, 120 black to white : 120 red to white. 240 red to black.


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[Paul L]

Originally Posted by SV Enough

Actually the 93-IXFMR7/5T-A will fully isolate both 120 outputs from each other and the dock. There are 2 separate 2:1 secondaries with center tap 120-0-120 when used in step down. It can also be used as a 1:1 isolation if 240 v is needed but I have no 240 aboard.

http://www.charlesindustries.com/mar...ual/7.5kva.pdf

See figure 1 page 6, 120 black to white : 120 red to white. 240 red to black.


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I don't see from that figure how you can put in two 120/30 shore power runs and get isolation to your two 120 internal setups. If you use two of the smaller transformers then you you can run 2x120 in or a 240 to a pigtail in. Plus the ability to move the smaller transformers and fit them is a lot easier.

[SV Enough]

Referring to figure 1. The 120 connections are on two separate secondary windings. There are 2, 30 amp secondary windings not one 60 amp with the two outputs both connected to it in parallel like a wye splitter.

Black to center tap, red to center tap. You get two individual single phase 120 v hot to neutrals. Neutral being the center tap which is always at zero volts due to the physics of how AC transformer coils work. Center taps are like the pivot point in a school yard Tedder toddler. The two ends (terminals) go up and down but the center pivot point remains fixed.

You can do the same thing with your two transformers to form a center tap between them, just like in fig 1 but using external wire.


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[Paul L]

I see the two secondary 120s out. What I am pointing out is that I don't see how you can have two 120/30 primaries in, like you would at a dock in the US. Since the boat is setup for 120 I'd think you want to be able to use the isolation transformer on both 120 and 240.

[SV Enough]

In fact depending how you connected the 2 transformers into you system you could have unknowingly formed a center tap neural arrangement in your system. If your system is truly hot to neutral on the 120 side you have to have done it without realizing it or you would have two hot legs with each leg having half the total volts (60/60) instead of 120/0.


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[SV Enough]

In Europe one 240 v single phase to neutral primary input. Two 120 single phase to neutral secondary outputs.

In the US I connect to a 240, 3 phase. Phase A to neutral is 120 (port), Phase B to neutral is 120 (stbd).


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[Paul L]

I have two internal 120ac runs. One is the house side the other is hot water heater and an a/c unit. There is two 120/30amp external connectors. These each run to a separate isolation transformer. When I'm using single phase 240, like I am now in NZ, I use a pigtail from the 240 to the two standard connectors and set the isolation transformers to be 240 to 120.

[Paul L]

Are you saying that the isolation transformer you linked to can handle US 120v inputs?

[SV Enough]

I have no isolation transformer in the US. I connect directly to the 240, 3 phase mains via a standard off the shelf Marinco single 240 to 2,120 wye splitter available at west marine, defender and other marine suppliers.

http://www.catalina30.com/TechLib/Wi...Electrical.pdf

Page 16


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[SV Enough]

Sorry page 15




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[DotDun]

Originally Posted by SV Enough

I have no isolation transformer in the US. I connect directly to the 240, 3 phase mains via a standard off the shelf Marinco single 240 to 2,120 wye splitter available at west marine, defender and other marine suppliers.

http://www.catalina30.com/TechLib/Wi...Electrical.pdf

Page 16


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Correction: you connect to 240v split phase main