Isolating Transformer.

[sailor0500]

I intend fitting one of the above. Can someone suggest a reasonably priced one and where to buy online. I don't use much AC power. Just desktop computer, 12v 30amp Sterling switchmode charger, and electric kettle.

[WotEver]

The Airlink always used to be the most reasonable but they’ve gone up a bit...

https://airlinktransformers.com/product/boating-transformer-bt3231

[Keeping Up]

5 minutes ago, sailor0500 said:

I intend fitting one of the above. Can someone suggest a reasonably priced one and where to buy online. I don't use much AC power. Just desktop computer, 12v 30amp Sterling switchmode charger, and electric kettle.

"I don't use much power" conflicts slightly with "electric kettle"

[Tracy D'arth]

Domestic electric kettle is 3kw, a lot. We use a travel kettle, 600w and big enough for 2 mugs, ha ha me and him.

[GUMPY]

25 minutes ago, WotEver said:

The Airlink always used to be the most reasonable but they’ve gone up a bit...

https://airlinktransformers.com/product/boating-transformer-bt3231

Gone up £100 in 14 years, mine was just under £200 in 2006. They didn't make boaty ones until I asked for one 

 

[WotEver]

Just now, Loddon said:

Gone up £100 in 14 years, mine was just under £200 in 2006. They didn't make boaty ones until I asked for one 

That's a 50% increase in 14 years.  Over the last 14 years my rates have gone down... 

[GUMPY]

2 minutes ago, WotEver said:

That's a 50% increase in 14 years.  Over the last 14 years my rates have gone down... 

Copper is getting scarce 

Its all in the hands of the commodity traders

 

[Tracy D'arth]

Nice to have if you can afford it and the electricity that it uses all the time even when you are using nothing.

[OldGoat]

I shouldn't ask ---

BUT

why do you need an isolation transformer?

with modern circuit breakers, panels and  earth loop breakers you are well protected.

 

Sometimes there's a misunderstanding as to why they are needed?

 

Sorry to ask - but it may save you "loads'a Monay"

[OldGoat]

1 minute ago, Tracy D'arth said:

Nice to have if you can afford it and the electricity that it uses all the time even when you are using nothing.

How so??

A transformer is a passive device and (if properly designed doesn't / shouldn't consume any power).

 

I await the onslaught of folks putting me right....

[Phoenix_V]

my "marine" Airlink isolation transformer failed it had

overheated, impossible to see if the winding's had gone or if it was just the surge limiter (which I suspected) due to everything inside being encapsulated.

replaced with an Airlink industrial toroidal transformer plus separate surge limiter not encapsulated but in my own fire proof box for rather less money. I also added some overheat safety cut outs for my own peace of mind.

57 minutes ago, OldGoat said:

How so??

A transformer is a passive device and (if properly designed doesn't / shouldn't consume any power).

 

I await the onslaught of folks putting me right....

They do use a small amount of current  whether they are better at protecting your boat against galvanic corrosion than the cheaper isolators has been debated elsewhere. In my case it also protects my English wiring against Belgian mains where their neutral is not tied to earth.

Edited September 29, 2020 by Phoenix_V

[Tracy D'arth]

5 minutes ago, OldGoat said:

How so??

A transformer is a passive device and (if properly designed doesn't / shouldn't consume any power).

 

I await the onslaught of folks putting me right....

Glad to please you, they do use power, not a lot, but the clue is that they get warm, and that energy is not delivered by the fairies.

[OldGoat]

2 minutes ago, Tracy D'arth said:

Glad to please you, they do use power, not a lot, but the clue is that they get warm, and that energy is not delivered by the fairies.

Oh, I must have been using top quality stuff.....

[GUMPY]

Mine is actually a non marine one, I dont care how little current it might consume  it protects my boat better than a GI  can.

 I just can't get on with the idea of having diodes which might fail  in a PE connection.

 

Edited September 29, 2020 by Loddon

[cuthound]

1 hour ago, OldGoat said:

How so??

A transformer is a passive device and (if properly designed doesn't / shouldn't consume any power).

 

I await the onslaught of folks putting me right....

 

All transformers have copper and iron losses. It is impossible to design a transformer with our resistance, inductance or eddy currents. However good design will minimise these losses.

[cuthound]

1 hour ago, Loddon said:

Mine is actually a non marine one, I dont care how little current it might consume  it protects my boat better than a GI  can.

 I just can't get on with the idea of having diodes which might fail  in a PE connection.

 

 

When I worked for BT all electro mechanical failures were recorded and analysed.

 

Wound devices (transformers, relays, inductors etc) had a higher failure rate than power electronics. The vast majority of power electronic component causes can be attributed to poorly specified components. 

[Tracy D'arth]

2 minutes ago, cuthound said:

 

All transformers have copper and iron losses. It is impossible to design a transformer with our resistance, inductance or eddy currents. However good design will minimise these losses.

Superconductors but the liquid helium is precious.  Can you get old transformers out of MR! units?

[Phoenix_V]

2 minutes ago, cuthound said:

 

When I worked for BT all electro mechanical failures were recorded and analysed.

 

Wound devices (transformers, relays, inductors etc) had a higher failure rate than power electronics. The vast majority of power electronic component causes can be attributed to poorly specified components. 

it is the failure mode that is relevant here, with a GI you may not know (dependant on design) if it has failed, with the IT the smell of burning and the stopping of the washing machine and all other electrics together with the tripping of everyone's shore supply alerts you.

[ditchcrawler]

4 hours ago, sailor0500 said:

I intend fitting one of the above. Can someone suggest a reasonably priced one and where to buy online. I don't use much AC power. Just desktop computer, 12v 30amp Sterling switchmode charger, and electric kettle.

And is that kettle 2 or 2.5Kw

3 hours ago, Loddon said:

 

 I just can't get on with the idea of having diodes which might fail  in a PE connection.

 

I'm with you on that

[ditchcrawler]

3 hours ago, Tracy D'arth said:

Domestic electric kettle is 3kw, a lot. We use a travel kettle, 600w and big enough for 2 mugs, ha ha me and him.

I think ours is 900 watt and the same physical size as a domestic one so if required can make 4 mugs of tea, just takes longer

[Tracy D'arth]

1 minute ago, ditchcrawler said:

And is that kettle 2 or 2.5Kw

Most are 3kw, that's  a lot if the inverter is anywhere near 220/230v output.

[cuthound]

11 hours ago, Phoenix_V said:

it is the failure mode that is relevant here, with a GI you may not know (dependant on design) if it has failed, with the IT the smell of burning and the stopping of the washing machine and all other electrics together with the tripping of everyone's shore supply alerts you.

 

True but a GI can be tested with a Digital Multimeter set to "diode test" and a short length of wire to discharge the capacitors in less than 30 seconds.

 

Many GI's come with failure indicators too.

 

I test mine monthly when on shore power and also whenever a breaker has tripped. However it is still functioning correctly in its 13th year.

Edited September 30, 2020 by cuthound
To unmangle the effects of autocorrect.

[GUMPY]

The only downside to the Airlink transformer is the soft start, it is just a thermistor with no bypass relay, this is not ideal and they do burn out. I ran mine for many years with no soft start but it did mean sometimes the shore MCB would trip when the power came back on after an outage.

Two years ago I replaced the soft start with something like this

https://www.ebay.co.uk/itm/402387460369

Still a thermistor but with a bypass relay and it works well.

 

[Phoenix_V]

52 minutes ago, Loddon said:

The only downside to the Airlink transformer is the soft start, it is just a thermistor with no bypass relay, this is not ideal and they do burn out.

 

 

I am sure that is what happened to mine extremely poor design burying it in the encapsualtion so nuking the whole unit if it fails,my new one is  quite separate and can easily be changed. It  is not on their website but they sold me a toroidal transformer wound 230/230 plus a board with the soft start, I overspecced and bought a 5kw transformer but fitted a 12 amp trip also an overheat cutout, as well as an asbestolux type box all cost less than their specific marine version

Edited September 30, 2020 by Phoenix_V

[GUMPY]

I thought the Thermistor wasn't within the potting compound.

 

Mine started life as one of these

https://airlinktransformers.com/product/enclosed-isolating-industrial-transformer-wm3602

So mine hasn't gone up in price as much as others. For 12 years it was in the shed next to the supply but since I moved moorings its  now housed with the soft start in an HDPE box , in a cupboard  at the back of the boat next to the inlet plug the inlet cable to the transformer is double insulated and in conduit just to be sure