Iso Transformers on a 460

[Graham Lorimer]

My 2002 460 Sundancer was built for the European market, it is a 220 volt boat, and was fitted with two C-Power Iso Transformers of 7.5 kva each.

Every time the pontoon power goes down, which happens quite often in Spain, when the power comes back on, the initial load that the Transformers take trips the pontoon power out, and if I am not on the boat, it then has no battery chargers running until next time I arrive, which can be a month or two.

When returning from a trip out, in order to plug back into shore power, I must go into the engine room, turn off the mains in switch, turn off the two power lines and everything else on the DB Board, and then plug in, otherwise it trips two different pontoon circuits on the pontoon.

Once plugged in, I have to turn everything else on in the correct order to prevent further trips.

According to the Q & A section of the C-Power website, this is called an inrush problem and recommends a soft start system, why would you not fit one at the build time if it was an issue???

I have already removed one of the Iso units, given that the Genset only supplies 6 kva I could not see the problem. Everything still runs fine but the tripping problem still exists.

I don't really want to fit a soft start system into the circuit, (expense) and wonder if it is a big deal to remove the second Iso unit altogether. Is there a big downside? I do know it takes up a lot of space in the engine room, and they weigh plenty. No other boats in my marina have these fitted that I am aware of.

Thoughts appreciated.


Graham

 

[SeaAyeOwe]

When you say it trips the pontoon power out, you mean the circuit breaker at the pontoon power outlet I assume. If that is so it may be as simple as doubling up across two breakers with a shore power y splitter, assuming you can access two outlets on the pontoon power pedestal. Second to that there are surge management circuit breakers that can be purchased if there is the possibility of changing out the existing breaker. They are designed to delay an over current trip and are usually used in electric motor applications where there is a starting torque current that is very high until the motor gets momentum.

If this is not the pontoon breaker that is tripping - the amount of AC components you would have to change on a 460 to allow a safe operation of 110v 60hz components on a 220v 50hz power supply would cost more than a soft start system. I would not personally even think about running a 110v boat on 220v power, in any circumstances. So many things that can go wrong even if you change out all the AC components.

There are some great marine electrical engineers on here that will offer more professional viewpoints.

 

[ttmott]

Graham
There are two types of devices that isolate the ground power for marine applications; isolation transformers and galvanic isolators. Both are designed to prevent galvanic corrosion of the boat metallic items. Technically the isolation transformer is a better means to achieve the protection and it fully isolates the ground power system from the boat's power system. Regardless, you really don't want to disable the galvanic corrosion protection devices.
http://www.westmarine.com/WestAdvisor/Preventing-Galvanic-Corrosion
On small transformers inrush current is incidental and should be of no concern however the current for a very short time will exceed the protective circuit breaker nominal current (amperage) rating. This is why thermal magnetic circuit breakers have a thermal overcurrent curve which will allow the circuit to experience overcurrent for a specified time. Most circuit breakers are of the thermal magnetic type. Your recommended "soft start" solution is normally for starting rotating equipment and, for the most part, no longer used; Variable Frequency Drives are now the industry standard to control current to motors and prevent voltage sag in a power system. Regardless, neither a soft start limiting device nor VFD will work to control or tolerate transformer inrush current.
The correct solution is to replace those breakers with new thermal magnetic ones that have the correct thermal time delay so they don't trip due to the nuisance short term over-current demand. It's explained pretty well here: http://news.waytekwire.com/choose-right-circuit-protection-devices/
And, for once Wikipedia has an accurate narrative on circuit breakers: https://en.wikipedia.org/wiki/Circuit_breaker

 

[Graham Lorimer]

When you say it trips the pontoon power out, you mean the circuit breaker at the pontoon power outlet I assume. If that is so it may be as simple as doubling up across two breakers with a shore power y splitter, assuming you can access two outlets on the pontoon power pedestal. Second to that there are surge management circuit breakers that can be purchased if there is the possibility of changing out the existing breaker. They are designed to delay an over current trip and are usually used in electric motor applications where there is a starting torque current that is very high until the motor gets momentum.

If this is not the pontoon breaker that is tripping - the amount of AC components you would have to change on a 460 to allow a safe operation of 110v 60hz components on a 220v 50hz power supply would cost more than a soft start system. I would not personally even think about running a 110v boat on 220v power, in any circumstances. So many things that can go wrong even if you change out all the AC components.

There are some great marine electrical engineers on here that will offer more professional viewpoints.

A misunderstanding, the boat was built as a 220 volt boat for Europe, and all components are 220 volt.

The Iso Transformers do not change the voltage, they are just something that is fitted to "clean up" the power supply to a boat.

GL

 

[Graham Lorimer]

Graham
There are two types of devices that isolate the ground power for marine applications; isolation transformers and galvanic isolators. Both are designed to prevent galvanic corrosion of the boat metallic items. Technically the isolation transformer is a better means to achieve the protection and it fully isolates the ground power system from the boat's power system. Regardless, you really don't want to disable the galvanic corrosion protection devices.
http://www.westmarine.com/WestAdvisor/Preventing-Galvanic-Corrosion
On small transformers inrush current is incidental and should be of no concern however the current for a very short time will exceed the protective circuit breaker nominal current (amperage) rating. This is why thermal magnetic circuit breakers have a thermal overcurrent curve which will allow the circuit to experience overcurrent for a specified time. Most circuit breakers are of the thermal magnetic type. Your recommended "soft start" solution is normally for starting rotating equipment and, for the most part, no longer used; Variable Frequency Drives are now the industry standard to control current to motors and prevent voltage sag in a power system. Regardless, neither a soft start limiting device nor VFD will work to control or tolerate transformer inrush current.
The correct solution is to replace those breakers with new thermal magnetic ones that have the correct thermal time delay so they don't trip due to the nuisance short term over-current demand. It's explained pretty well here: http://news.waytekwire.com/choose-right-circuit-protection-devices/
And, for once Wikipedia has an accurate narrative on circuit breakers: https://en.wikipedia.org/wiki/Circuit_breaker

I appreciate your reply on this.

Given that all other boats (and my last Sea Ray 400 DA) don't appear to have these fitted, is there a big issue in removing the Iso Transformer?

I would think trying to get the Spanish operators of the Marina to change the breakers just for me might be a real hassle if not impossible. And when we go to any other Marina for a short stay, the problem is still there.

I should say I bought the boat over 400 miles from the berth it is now in, and the same problem was happening there after the sea trial, I just did not realize it was not a one off

GL

 

[ttmott]

I would say then there is a fault in the boat's electrical system somewhere. So first, is the entire boat's electrical system designed for 220 VAC 50 hertz? Assuming so, the transformer is truly an isolation device and does not raise or lower the voltage; the placard on the transformer will tell this. If this is the case then as a test bypass the isolation transformer and then determine if the marina's breakers continue to trip. If they do then the transformer is not the issue; conversely, if they do not then the transformer has a fault and needs to be replaced.
Regardless, I wouldn't remove the boat's protective devices. You could as an alternative replace the isolation transformers with galvanic isolators but to what end....
Regarding your 400DA it did have galvanic isolators; they were located behind and above the 12 VDC breaker panel in the salon.

 

[Graham Lorimer]

"replace the isolation transformers with galvanic isolators but to what end...."

Replacing the ISO Transformer with a new one would be seriously expensive, freight alone would be significant. And my concern is that there is already a stated problem on the C-Power website “Q&A” it calls it an inrush problem and recommends a soft start system. I would be concerned that the problem would still be there.

A previous poster on this thread has suggested "Regardless, neither a soft start limiting device nor VFD will work to control or tolerate transformer inrush current".

A Glavanic Isolator is only about $300 and I could take it down in my hand luggage. Can someone tell me where I would look to see if my boat already has a Galvanic Isolator please.

GL

 

[ttmott]

Graham
You would have one or the other but not both as they perform the same function.
Alternatively, there are a lot of other yacht manufacturers in Europe that have isolation devices in the boats so I would think you could go to Princess or Beneteau dealers and get a similar replacement.
Just some thoughts.

 

[Graham Lorimer]

Graham
You would have one or the other but not both as they perform the same function.
Alternatively, there are a lot of other yacht manufacturers in Europe that have isolation devices in the boats so I would think you could go to Princess or Beneteau dealers and get a similar replacement.
Just some thoughts.

Thanks, I think that may be the way forward to prevent these issues.

GL

 

[SeaAyeOwe]

A misunderstanding, the boat was built as a 220 volt boat for Europe, and all components are 220 volt.

The Iso Transformers do not change the voltage, they are just something that is fitted to "clean up" the power supply to a boat.

GL

I see, my bad.

 

[HUMPH]

"replace the isolation transformers with galvanic isolators but to what end...."

Replacing the ISO Transformer with a new one would be seriously expensive, freight alone would be significant. And my concern is that there is already a stated problem on the C-Power website “Q&A” it calls it an inrush problem and recommends a soft start system. I would be concerned that the problem would still be there.

A previous poster on this thread has suggested "Regardless, neither a soft start limiting device nor VFD will work to control or tolerate transformer inrush current".

A Glavanic Isolator is only about $300 and I could take it down in my hand luggage. Can someone tell me where I would look to see if my boat already has a Galvanic Isolator please.

GL

You do have them according to your owner's manual. Your parts manual should show you where they are located...

 

[fr8dog]

If your boat was equipped from Sea Ray with an Iso Transformer system, I doubt you have galvanic isolators. Would not make sense to have both.