milsat
Junior Member
Same man just looking backwards.
Posts: 11
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Post by milsat on Sept 10, 2017 11:21:46 GMT
As it happens the Airlinks are made in Harlow (apart from the varistor of course) It looked a soild piece of kit, weighed a ton and never appeared to get unduly hot under load. But encapsulating everything is a major design fault - when I replace it I will look at whether that has/can be changed or buy elsewhere,China not excluded. Varistors should be regarded as consumable, like slow blow fuses they can only take so many 'hits' especially if connected to a 'dirty' mains supply and it isn't a good idea to pot them up. How do I know this?....... If the soft start uses one as loddon says the transformer will work fine without. Might be a money saver to visit fleabay for a bottle of solvent and bypassing the Vr. If that is what has failed.
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Post by JohnV on Sept 10, 2017 12:00:12 GMT
The only problem that might occur is tripping of the shore mcb upon connection or switch on.
Toroidal transformers have a very high inductance and a low resistance so they have a larger "switch on surge" than transformers wound on traditional laminations.
A lot depends on the current rating and the class of the mcb in the shore supply and even the length and size of the shore lead.
eta this of course refers to running the transformer without a varistor
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Post by Telemachus on Sept 10, 2017 13:25:17 GMT
... and also the magnetic state of the core when you switched it off, and the phase of the supply when you switch it on. In other words, if it trips the first time, trying again may be more successful.
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Post by phoenix on Sept 13, 2017 7:27:15 GMT
I have spoken to Airlink and taken some measurements, there appears to be an electrical link between input and output but no short to the earth safety screen which suprised me, conclusion shorted turns somewhere on the transformer, in any event it cannot be dismantled and is fucked. Now I have been having a browse around Airlink's website and the first thing that comes across is that they no longer appear to offer an earth safety screenon the boating tansformers, second the boating transformers are more expensive than their ordinary range, when I asked the difference it appears the only thing is they have not joined the input and output earth, thirdly they make two 3600va transforers, the potted one weighs 21kg, the metal cased one weighs in at 31kg but costs rather more than the potted one, both potted one and metal one are larger than the dead one that i have and will not fit my cupboard. All of which leads me to suspect that they put the price of the boaty ones higher than the others because they can and that my transformer (and all of that era) may have been underspecced and may still be and leaves me with the problem of how to fit a new one in. I have come to the conclusion that I should buy this airlinktransformers.com/product/chassis-mounting-toroidal-transformer-standard-range-cm5000172 bare bones transformer, adding a slow start device and 16 amp breaker, it will fit nicely and is overrated, 1) Can the team see any reason not to go down this route? 2) Should I install one of the screens offered under the customize tab? 3) Could I install a thermal cut out for extra protection, what would I need and how would I wire it? I have looked elsewhere for transformers but everywhere else seems more expensive and whilst you get what you pay for not noticeably better just judging by weight.
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Post by Graham on Sept 13, 2017 8:09:26 GMT
I have spoken to Airlink and taken some measurements, there appears to be an electrical link between input and output but no short to the earth safety screen which suprised me, conclusion shorted turns somewhere on the transformer, in any event it cannot be dismantled and is fucked. Now I have been having a browse around Airlink's website and the first thing that comes across is that they no longer appear to offer an earth safety screenon the boating tansformers, second the boating transformers are more expensive than their ordinary range, when I asked the difference it appears the only thing is they have not joined the input and output earth, thirdly they make two 3600va transforers, the potted one weighs 21kg, the metal cased one weighs in at 31kg but costs rather more than the potted one, both potted one and metal one are larger than the dead one that i have and will not fit my cupboard. All of which leads me to suspect that they put the price of the boaty ones higher than the others because they can and that my transformer (and all of that era) may have been underspecced and may still be and leaves me with the problem of how to fit a new one in. I have come to the conclusion that I should buy this airlinktransformers.com/product/chassis-mounting-toroidal-transformer-standard-range-cm5000172 bare bones transformer, adding a slow start device and 16 amp breaker, it will fit nicely and is overrated, 1) Can the team see any reason not to go down this route? 2) Should I install one of the screens offered under the customize tab? 3) Could I install a thermal cut out for extra protection, what would I need and how would I wire it? I have looked elsewhere for transformers but everywhere else seems more expensive and whilst you get what you pay for not noticeably better just judging by weight. How old is the transformer? I assume you bought it as a consumer and it was not a Co purchase? UK purchase or delivered to France? You could have a case under the consumer acts if it is less than 6 years old. Which means you could get a hefty discount off a new one.
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Post by Telemachus on Sept 13, 2017 8:13:51 GMT
I don't know much about ITs but the following thoughts occur:
Since you only shore power every now and again and for short periods, why not get a GI instead? One with a meter or LEDs so you know what's going on. With regular functional checks (checking for diodes open or short circuit) and one compliant with the ABYC standard, it is in practice as safe and effective as an IT as long as you keep an eye on the meter/LEDs.
If you go down the route of buying the bare transformer, what will you put it in? If you put it in a metal box, the box and the transformer screen should be earthed to land-side so the box has to be robustly isolated from the hull. If you put it in a plastic box, this will not tolerate a transformer overheat/fire.
It's likely to be noisier than an encapsulated one, will that be a problem (depends on the location)?
It's not clear from the spec whether the transformer has an accessible shield between in and out - the general idea is to connectbthis to shore earth but I'd want to be certain that connection exists.
The extra screening mentioned is for reduction in electrical/electronic interference. Unless you will have it close to sensitive electronics I wouldn't bother, ditto if you are putting it in a metal box. A thermal cutout would be wired in series with the incoming live, obviously it would have to be rated to pass and interrupt the maximum current with some margin (overheating being likely to occur due to overload). But I would think that if the transformer is protected by an MCB and RCD there is probably little point in an overheat trip.
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Post by phoenix on Sept 13, 2017 15:36:59 GMT
Thanks for the reply, some food for thought,a few more questions if I may I don't know much about ITs but the following thoughts occur: Since you only shore power every now and again and for short periods, why not get a GI instead? One with a meter or LEDs so you know what's going on. With regular functional checks (checking for diodes open or short circuit) and one compliant with the ABYC standard, it is in practice as safe and effective as an IT as long as you keep an eye on the meter/LEDs. - in the winter we will be on shore power all the time (for frost heaters) also mains here (Belgium appears to have floating live and neutral so an IT will restore earthed negative as expected by our UK spec equipmentIf you go down the route of buying the bare transformer, what will you put it in? If you put it in a metal box, the box and the transformer screen should be earthed to land-side so the box has to be robustly isolated from the hull. If you put it in a plastic box, this will not tolerate a transformer overheat/fire. It would go in the (wooden) cupboard with the other electrical equipment so no need for a box other than if fire risk is significant, in which case constructing something from masterboard would seem more sensible than introducing all the complications of a metal case and where to earth itIt's likely to be noisier than an encapsulated one, will that be a problem (depends on the location)? Oh could beIt's not clear from the spec whether the transformer has an accessible shield between in and out - the general idea is to connectbthis to shore earth but I'd want to be certain that connection exists. No shield but then nor do their boat transformers now, good idea in theory but does not seem to have helped in my caseThe extra screening mentioned is for reduction in electrical/electronic interference. Unless you will have it close to sensitive electronics I wouldn't bother, ditto if you are putting it in a metal box. Would it make a difference to radios etc in boat BBC radio 4 longwave seems to pick up anything going, what is the difference between the 2 types they offer?A thermal cutout would be wired in series with the incoming live, obviously it would have to be rated to pass and interrupt the maximum current with some margin (overheating being likely to occur due to overload). But I would think that if the transformer is protected by an MCB and RCD there is probably little point in an overheat trip. I was thinking of the fire hazard, do you know of any makes/part numbers that would be suitable, my query about where to put it is that presumably if it is just somewhere in the input lead that may be considerably cooler than the hot core of the lump or is that not how they work?
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Deleted
Deleted Member
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Post by Deleted on Sept 13, 2017 15:42:07 GMT
This is the stuff of internet forum legends.
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Post by Telemachus on Sept 13, 2017 16:03:51 GMT
Thanks for the reply, some food for thought,a few more questions if I may I don't know much about ITs but the following thoughts occur: Since you only shore power every now and again and for short periods, why not get a GI instead? One with a meter or LEDs so you know what's going on. With regular functional checks (checking for diodes open or short circuit) and one compliant with the ABYC standard, it is in practice as safe and effective as an IT as long as you keep an eye on the meter/LEDs. - in the winter we will be on shore power all the time (for frost heaters) also mains here (Belgium appears to have floating live and neutral so an IT will restore earthed negative as expected by our UK spec equipmentIf you go down the route of buying the bare transformer, what will you put it in? If you put it in a metal box, the box and the transformer screen should be earthed to land-side so the box has to be robustly isolated from the hull. If you put it in a plastic box, this will not tolerate a transformer overheat/fire. It would go in the (wooden) cupboard with the other electrical equipment so no need for a box other than if fire risk is significant, in which case constructing something from masterboard would seem more sensible than introducing all the complications of a metal case and where to earth itIt's likely to be noisier than an encapsulated one, will that be a problem (depends on the location)? Oh could beIt's not clear from the spec whether the transformer has an accessible shield between in and out - the general idea is to connectbthis to shore earth but I'd want to be certain that connection exists. No shield but then nor do their boat transformers now, good idea in theory but does not seem to have helped in my caseThe extra screening mentioned is for reduction in electrical/electronic interference. Unless you will have it close to sensitive electronics I wouldn't bother, ditto if you are putting it in a metal box. Would it make a difference to radios etc in boat BBC radio 4 longwave seems to pick up anything going, what is the difference between the 2 types they offer?A thermal cutout would be wired in series with the incoming live, obviously it would have to be rated to pass and interrupt the maximum current with some margin (overheating being likely to occur due to overload). But I would think that if the transformer is protected by an MCB and RCD there is probably little point in an overheat trip. I was thinking of the fire hazard, do you know of any makes/part numbers that would be suitable, my query about where to put it is that presumably if it is just somewhere in the input lead that may be considerably cooler than the hot core of the lump or is that not how they work?I'm a bit out of my comfort zone giving you advice in this area, however: Are you sure there is not normally a screen between primary and secondary windings? Seems unlikely that the enamel winding insulation is the only insulation between primary and secondary. As to the two sorts of shield, they both seem to serve similar purposes, not sure of the fine detail except that the copper one is slightly more expensive so presumably a bit more effective. Unless you intend to have the radio very close to the transformer, I don't think it will be an issue. overheat device - sorry I just meant where in terms of the wiring, obviously it needs to be located near the potentially hot bit (the transformer. you could get a remote and adjustable one like this uk.rs-online.com/web/p/thermostats/7334726/Or a more compact thing like this: uk.rs-online.com/web/p/thermostats/0339308/ but note it's only 15A - you'd have to look around for something with a 16A or greater rating. In either case you would have to go to some trouble to protect people from coming into contact with the bare live connections. You wouldn't want to be able to open a cupboard and have access to a live terminal which just had a bit of tape on it! Personally I wouldn't bother with either.
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Post by smileypete on Sept 13, 2017 18:38:24 GMT
One could argue that leaving a boat based isolation transformer unattended for long periods is a bit risky, the shoreline could rub through and make the hull live unless there's an RCD on the shore side. Maybe use a shoreline made from braided cable? (type SY): www.tlc-direct.co.uk/Products/MF2dot5slash3.htmlSans IT, maybe run the frost protection heaters off an extension lead with a passive (latching) RCD at the shore end of the lead, something like this: www.screwfix.com/p/bg-13a-switched-weatherproof-rcd-fcu/20523Then when back on the boat just use a decent GI with LED status monitor on a normal shoreline inlet.
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Post by phoenix on Sept 13, 2017 18:38:59 GMT
This is the stuff of internet forum legends. ?
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Deleted
Deleted Member
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Post by Deleted on Sept 13, 2017 18:44:26 GMT
This is the stuff of internet forum legends. ? I just thought it was good quality discussion on an electrical topic which is slightly unusual on here. A Good Thing.
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Post by smileypete on Sept 13, 2017 18:49:41 GMT
I have come to the conclusion that I should buy this airlinktransformers.com/product/chassis-mounting-toroidal-transformer-standard-range-cm5000172 bare bones transformer, adding a slow start device and 16 amp breaker, it will fit nicely and is overrated, 1) Can the team see any reason not to go down this route? 2) Should I install one of the screens offered under the customize tab? 3) Could I install a thermal cut out for extra protection, what would I need and how would I wire it? I have looked elsewhere for transformers but everywhere else seems more expensive and whilst you get what you pay for not noticeably better just judging by weight. I'm a bit wary of advising on matters like this for liability reasons. Probably easier to mod the cupboard space or find somewhere else on the boat to fit an off the shelf IT.
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Post by phoenix on Sept 13, 2017 19:04:06 GMT
Thanks for the reply, some food for thought,a few more questions if I may I'm a bit out of my comfort zone giving you advice in this area, however: Are you sure there is not normally a screen between primary and secondary windings? Seems unlikely that the enamel winding insulation is the only insulation between primary and secondary. its what he said but does seem strange will ask again
As to the two sorts of shield, they both seem to serve similar purposes, not sure of the fine detail except that the copper one is slightly more expensive so presumably a bit more effective. Unless you intend to have the radio very close to the transformer, I don't think it will be an issue. Thanksoverheat device - sorry I just meant where in terms of the wiring, obviously it needs to be located near the potentially hot bit (the transformer. you could get a remote and adjustable one like this uk.rs-online.com/web/p/thermostats/7334726/Or a more compact thing like this: uk.rs-online.com/web/p/thermostats/0339308/ but note it's only 15A - you'd have to look around for something with a 16A or greater rating. In either case you would have to go to some trouble to protect people from coming into contact with the bare live connections. You wouldn't want to be able to open a cupboard and have access to a live terminal which just had a bit of tape on it! Personally I wouldn't bother with either. Yes was thinking of the fire risk and I have seen some its specified with them, but just switching off waiting for it to cool down then on again as they would in an endless cycle if there is overload wouldnt be helpful eitherThanks again for your thoughts
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Post by phoenix on Sept 13, 2017 19:08:56 GMT
One could argue that leaving a boat based isolation transformer unattended for long periods is a bit risky, the shoreline could rub through and make the hull live unless there's an RCD on the shore side. Maybe use a shoreline made from braided cable? (type SY): www.tlc-direct.co.uk/Products/MF2dot5slash3.html but wouldnt that earth the hull to the shoreSans IT, maybe run the frost protection heaters off an extension lead with a passive (latching) RCD at the shore end of the lead, something like this: www.screwfix.com/p/bg-13a-switched-weatherproof-rcd-fcu/20523 might be a lot simpler/cheaper but wouldnt that leave the hull unearthed with respect to the supply which everyone says is a no no and would it work Ok with Belgian floating live and neutral/
Then when back on the boat just use a decent GI with LED status monitor on a normal shoreline inlet.
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