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Isolation transformer and connection to ground
Thanks for the info. I was not aware of the product and as you can
imagine, I have no experience with it. My comments are therefore necessarily abstract. The two primary advantages of a switch-mode device are lower weight (less iron) and a built-in capability to regulate output voltage (and perhaps adjust for different input voltages) automatically. Potential disadvantages, however, are numerous. The standard isolation transformer is perhaps the most reliable electrical component we have. Switch-mode circuits tend to involve many electronic components, some of which operate under life-shortening stresses. While an isolation transformer could easily outlast a boat, I doubt the same could be said of the vastly more complex switch-mode devices. Without examining the actual circuit, it is impossible to discuss the degree of isolation achieved or the potential isolation fault modes of the device. No mention is made in the specifications about the purity of the sine wave output. For some appliances, this may not be critical; for others, it is very important. Possible electronic noise from the switching circuits could also be troublesome. While modern switch-mode circuits can be designed to deal acceptably with these issues, it is difficult to evaluate the product to which you refer since no mention of them is made on the website. Other considerations are susceptibility to noise and voltage transients (e.g., lightning) on the shore power line and radio frequency interference from onboard radios, battery chargers, fluorescent lamps, and radar. It is unclear how the ABYC and various EU standards will view such a device. Sorry I can't offer anything more specific. Perhaps others have had some experience with switch-mode isolation devices. Good luck. Chuck Daniele Fua wrote: chuck wrote: ...snip A short on either primary or secondary would trip the breaker, of course, provided it has been sized properly. ...snip Chuck I am following your discussion with much interest as I am planning to install very soon an isolation transformer in my boat. I add a further question: I have just learnt that a firm is going to commercialize a Switch-Mode Isolation Transformer (they claim is the first in the world!) and, if you are interested, just make a Google search. My question is: is it indeed equivalent to the ol' faithful and massive isolation transformers? Thanks for your help Daniel |
#2
posted to rec.boats.electronics
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Isolation transformer and connection to ground
Chuck,
I have been down the route of automatic inrush control. The circuit I designed was keyed off of secondary voltage in that when secondary voltage was developed, would the relay short the lamp. This worked very well, but I like the manual switch better. It is cheap clean and bulletproof. On the switched transformers the problem is efficiency, reliability and noise. I do use however a modified UPS for minor AC use and it works a treat. It is a 1400 KVA Smart UPS by APC, but instead of using it off internal batteries, I run it off ship's batteries (24V). Normally it will not fire up without an external AC source, but if you use the undocumented cold start procedure, it will. It has an additional utility as well. When pluged into shore power and is powered up, it will act as an intelligent battery charger, keeping the ships batteries fresh. Steve "chuck" wrote in message hlink.net... Thanks for the info. I was not aware of the product and as you can imagine, I have no experience with it. My comments are therefore necessarily abstract. The two primary advantages of a switch-mode device are lower weight (less iron) and a built-in capability to regulate output voltage (and perhaps adjust for different input voltages) automatically. Potential disadvantages, however, are numerous. The standard isolation transformer is perhaps the most reliable electrical component we have. Switch-mode circuits tend to involve many electronic components, some of which operate under life-shortening stresses. While an isolation transformer could easily outlast a boat, I doubt the same could be said of the vastly more complex switch-mode devices. Without examining the actual circuit, it is impossible to discuss the degree of isolation achieved or the potential isolation fault modes of the device. No mention is made in the specifications about the purity of the sine wave output. For some appliances, this may not be critical; for others, it is very important. Possible electronic noise from the switching circuits could also be troublesome. While modern switch-mode circuits can be designed to deal acceptably with these issues, it is difficult to evaluate the product to which you refer since no mention of them is made on the website. Other considerations are susceptibility to noise and voltage transients (e.g., lightning) on the shore power line and radio frequency interference from onboard radios, battery chargers, fluorescent lamps, and radar. It is unclear how the ABYC and various EU standards will view such a device. Sorry I can't offer anything more specific. Perhaps others have had some experience with switch-mode isolation devices. Good luck. Chuck Daniele Fua wrote: chuck wrote: ...snip A short on either primary or secondary would trip the breaker, of course, provided it has been sized properly. ...snip Chuck I am following your discussion with much interest as I am planning to install very soon an isolation transformer in my boat. I add a further question: I have just learnt that a firm is going to commercialize a Switch-Mode Isolation Transformer (they claim is the first in the world!) and, if you are interested, just make a Google search. My question is: is it indeed equivalent to the ol' faithful and massive isolation transformers? Thanks for your help Daniel |
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