Sine Waves, Instant Volt, and a headache...

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roger

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Electrician
Dweeber said:
Cuolter: I tried three times with a well writen response, but I time-out (?) before I can send it. Here the quick: The sentiment I read in your response is very similar to my reaction. Thanks, you have confirmed what I've been thinking.

Brian John: Thanks for your experience and results. I had an educated hunch that under particular circumstances, the result may be favorable.

D.
D, just a tip, when putting together a long post you can compose it in say MSWord or Works and then copy and paste it into a post.

Roger
 

Dweeber

Member
All righty then...

All righty then...

First off, I'd like to thank all that replied.

Steve066: Your reply is in alignment of what I am trying to do, get the hard data and see what it can/cannot do.

Roger: Thanks for the posting tip. I was surprised,then frustrated, then mildly annoyed when I tried to reply, checked it over once or twice, then lost it to the cyber-world, three times. My darling wife just looked over my shoulder and said, no less than three minutes ago, "why didn't you just listen to me?", this was in regards to the copy paste method. Uh, is there another forum on this board for deaf husbands? Thanks,

D.
 

dbuckley

Senior Member
Some static switches can switch between unsyncronised sources in a fraction of a cycle but to do so the failing source must have dropped voltage to insignificant. So if you have a breaker open and the voltage collapses immediately you can be onto the second source, whether syncronised or unsyncronised in under a millisecond, assuming your loads can tolerate an out-of-phase transfer. But, if the first source decays gently (say a generator stopping on-load) you have to wait for a zero cross point on each phase to switch to the secondary source.

There is no way to parallel out of phase sources, and to try to do so could result in spectacular fault currents. If you try to parallel out of phase generators then the usual result is mechanical damage, often severe. I don't know of any static transfer switches that parallel sources at all, but that doesn't mean they don't exist. Mechanical breakers are the norm for this role.

Based on info provided so far, you need an expert. I'm very good at keeping data centres up and running, but that doesn't qualify me to fool with safety critical and life supporting systems.
 
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steve066

Senior Member
Dweeber:

You didn't say exactly what this transfer switch will be serving. But if your peers have found a magic transfer switch that can parallel two sources, you should make sure the switch is listed (a UL listing or similar) for the system you intend to use it on.

The National Electric Code has a phrase for that goes something like "Transfer equipment shall be listed for emergency use." This requirement only applies to certain emergency systems. (I don't have my code book with me, so I can't be more specific right now.)

Steve
 

brian john

Senior Member
Location
Leesburg, VA
steve066 said:
Dweeber:

You didn't say exactly what this transfer switch will be serving. But if your peers have found a magic transfer switch that can parallel two sources, you should make sure the switch is listed (a UL listing or similar) for the system you intend to use it on.
It is not magic, this is done all the time, you just need to be able to keep the two (or more) sources in sync.

[/quote]The National Electric Code has a phrase for that goes something like "Transfer equipment shall be listed for emergency use." This requirement only applies to certain emergency systems. (I don't have my code book with me, so I can't be more specific right now.)

Steve[/QUOTE]

Emergency or not paralleling ATS's are not all that uncommon and a multitude of manufactures make these static, mechanical or a combination of both.
 

steve066

Senior Member
brian john said:
It is not magic, this is done all the time, you just need to be able to keep the two (or more) sources in sync.
I was refering an ATS that parallels two sources that are out of sync.
 

Dweeber

Member
Wow....there's a lot to think about...

Wow....there's a lot to think about...

Dbuckley: fantastic response, you've spoke/written what I was hoping to understand. Thanks.

Steve066: There is a bit of info I cannot give, I am unable to do so, and I am unsure I could, even if I knew all the details. Please don't let my inability to give you "good" info prevent you from responding.

BrianJohn: There's a lot for me to glean from all the back and forth, and I appreciate what you have to say. You obviously have a lot of knowledge in a variety of fields. I thank you for your input.

D.
 
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