3 Pole vs 4 Pole Circuit Breaker Usage
3 Pole vs 4 Pole Circuit Breaker Usage
(OP)
Hi Mates,
kindly illustrate the difference between 3 pole circuit breakers with 4 pole.
one quite significant difference i aware is on the price between 3pole vs 4 pole based on same rating.Because 3pole cheaper, so we always facing recommendation to use 3 pole rather than 4 pole.
Therefore need your help to understand more on the difference in application between 3 pole with 4 pole.
thanks.
kindly illustrate the difference between 3 pole circuit breakers with 4 pole.
one quite significant difference i aware is on the price between 3pole vs 4 pole based on same rating.Because 3pole cheaper, so we always facing recommendation to use 3 pole rather than 4 pole.
Therefore need your help to understand more on the difference in application between 3 pole with 4 pole.
thanks.






RE: 3 Pole vs 4 Pole Circuit Breaker Usage
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
But Skogsgurra, why is TN-S systems must switch the neutral pole at the same time? Kindly elaborate more on the technical side?
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
One is that the N conductor often has a smaller area than the L1-L3 conductors and that means that the N conductor can be overloaded if it is not protected and can be opened in case of an overload.
Another reason is that the N conductor usually has some residual voltage on it. If you want to make sure that an installation is completely "dead" (=no potential at all), then you need to break also the N conductor. This is often the case in hospitals.
This Schneider link has more information. http:/
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
TN-S system, that mean : Neutral conductor (N) and protective conductor (PE) are separated.
BTW, additional systems:
TN-C : N and PE are combinated , now is PEN.
TN-C-S, you have combination of both of system
And, what I remambare: N-is blue color and PE is yellow/green color. And additional systems are TT and IT ( isolated system or HI sytems)
Regards.
Slava
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
it's some very schematic drw. I try found my old papers with "better" drw.
Regards.
Slava
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
amount of Triplen Harmonics. This would be a result from
a Delta-Wye transformer connection. The triplens are not
cansuled in the neutral as other currents,but they add
as much as 1.73 X phase current. Single phase computer
systems are well known for this (non-linear loads).
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
There is more to grounding than you think. What is the ultimate truth in the US may not be the truth in Europe. And, without being overly partial, I dare say that we have analysed these problems a lot more thoroughly than you have on your side of the pool. Read and learn!
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
I would like add :
http
and
http://w
Regards.
Slava
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
I hope you are hiding in a bunker!
Slava,
Thanks for that IEE download. I have seen it but lost my copy. - I want to send it to a few guys at work.
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If we learn from our mistakes I'm getting a great education!
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
I'm not convinced that switching neutrals is a viable means of getting around the problems created by having two neutral-ground bonds when one is trying to detect ground faults using a residual connection.
I don't know which side of the pond may have done the most research on the topic, but regardless both sides of the pond seem to be comfortable with what they do and rather uncomfortable some of the practices on the other side of the pond.
In the example of the figures cited, I would leave the wye points ungrounded and bring in four wires, landing the neutral on the switchgear neutral bus and then forming a single neutral-ground bond in the gear. That way there is only one return path for ground faults and they can be readily detected and cleared.
But if you are satisfied with the safety and efficacy of the protection for your system designs then I won't argue with you.
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
The big conceptual problem seems to be that we make a very definitive difference between Neutral and Ground in TN-S installations. During my visit this October to some drive installations in Elizabeth, NJ, I was told by the foreman that everything had been done wrong in those cranes. Mainly because of the way the Neutral and Ground were connected and used.
It takes some exposure to a system to fully understand it. The TN-S system is not just another way of doing it. It is a way of keeping installations safe in a lot of fault situations. But, surely, it can be a can of worms for those that are not used to think "outside the NEC".
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
As David alluded to, residual connected earth fault detection becomes unpredictable with multiple neutral-earth bonds, but multiple neutral-earth bonds are not permitted under UK regulations except in a PME installation. PME installations are explicitly prohibited in the UK except for utility distribution systems so for most people the problem of multiple neutral earthing does not arise if a four-pole breaker is used to open the neutral when disconnecting the source, thus removing the neutral-earth bond at the origin of that supply. A three pole breaker would leave an additional neutral-earth bond connected which would potentially upset any residually connected earth fault detection relay such as those commonly fitted within ACBs, in addition to being a code violation. I guess the US solution would be to use an isolation transformer for each supply and locally earth the transformer secondary neutral point on the switchgear?
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If we learn from our mistakes I'm getting a great education!
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
David, in his post could have been wary of correcting problems related with too many ground paths for residual-connected earth fault protections!
Also, newer systems configurations on the other side of the pond require newer electrical protection equipment! Makes millions!
I prefer more simple and cheaper systems!
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
What is system in US, like to TT?
Regards.
Slava
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
If there is another ground source, such as a delta-wye transformer or a generator, it is a "separately derived source" and it's neutral is grounded at the source. NEC prohibits grounding the neutral at more than one point in each separately derived system. If you have two separately derives sources connected to a transfer switch, then you need a four-pole transfer switch to switch the neutral so that it is only grounded at one point in each separately derived system. If there are breakers connecting two separately derived system, then they need to be four-pole breakers for the same reason.
This doesn't seem too different from what the common European practice is, based on references in previous posts.
You can have a generator connected to a three-pole transfer switch, but the neutral cannot be grounded both at the generator and at the service disconnect. The problem with this is that if the neutral is grounded only at the service and the system is running on the generator, ground fault current would have to flow through the protective ground to the service and then flow through the neutral to the generator source. This increases the impedance and can increase fault clearing times.
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
Where is the installation to be? What with pond-sides and all, that may well be the dominant factor. Right guys?! A 4-pole breaker may be used in other instances where 4 phase conductors are to be disconnected simultaneously.
Thanks to some of our regular contributors for continuing to share some of their expertise and insights (and links!!!) with us. (bunkers notwithstanding)
I know I've learned a bit from this thread!
RE: 3 Pole vs 4 Pole Circuit Breaker Usage
More or les both of systems have same advantages and disadvantages.
We use both of system, but deciding is case by case.
Regards.
Slava