Circuit Switcher vs. Circuit Breaker
Circuit Switcher vs. Circuit Breaker
(OP)
What is the difference between a Circuit Switcher and a Circuit Breaker?
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Circuit Switcher vs. Circuit Breaker
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RE: Circuit Switcher vs. Circuit Breaker
if you want to install a chillar as an example you need to install a circuit switch near you for maintenance purpose,
then you can be sure that no body could switch on power by mistake .so you should install a circuit switch (isolator ) to cut the power and control it . You don't need to install a circuit breaker.
RE: Circuit Switcher vs. Circuit Breaker
RE: Circuit Switcher vs. Circuit Breaker
The primary difference is the interrupting rating. The circuit breaker will generally have a higher short circuit interrupting and withstand capability, and is capable of high speed reclosing.
The circuit switcher generally has a lower interrupting rating and is not applied in reclosing applications. But it is much less expensive. These are typically applied for high-side transformer protection.
RE: Circuit Switcher vs. Circuit Breaker
RE: Circuit Switcher vs. Circuit Breaker
Mark in Utah
RE: Circuit Switcher vs. Circuit Breaker
IEEE is working to make a standard for the Switcher. They already have a draft standard (P1367).
The draft gives following definition:
QUOTE:
A mechanical switching device with an integral interrupter, suitable for making, carrying, and interrupting currents under normal circuit conditions. It is also suitable for interrupting specified short-circuit current that may be less than its close and latch, momentary, and short-time current ratings.
NOTE: This device may be suitable for transformer protection where the majority of faults are limited by the transformer and system impedance.
UNQUOTE:
This means it is to be used on the inputside of the transformer in a radial system. Any fault on the output side of the transformer will be limited by the transformer (and system) impedance.
Some countries call them interrupters. They are mainly used in railway application. There is always a breaker behind this interrupter.
The difference is very thin and difficult to appreciate. I can not appreciate. However, it is that way.
Hope this clarifies the subject.
RE: Circuit Switcher vs. Circuit Breaker
RE: Circuit Switcher vs. Circuit Breaker
The pragamatist will always claim that a piece of equipment can always interrupt a fault, but there may be pieces of it around the yard.
As for S&C, they have a very good reputation in the industry. I have no problem accepting their ratings at their word. You have the same problem with all manufacturers. Can you guarantee that ABB hasn't fudged on their ratings? G.E.? Siemens? You can't, but you can bet that if you buy your equipment from manufacturers with a proven reputation, they've probably not fudged the numbers.
Mark in Utah
RE: Circuit Switcher vs. Circuit Breaker
I'm going from memory here, but when I applied S & C Mk V circuit switchers at 69 and 138 kV, I recall several different application categories numbered A, B, C, etc. The IC ratings varied between categories. We used the Mk V for transformer protection/switching, and I recall it only had about an 8 kAIC rating for that application.
I guess the difference between S & C and manufacturers of ANSI rated gear is that ANSI is an independent body that publishes standards detailing the minimum construction features and test procedures, and defines the ratings. The manufacturer may try to fudge, but you can ask for certified test results and compare them against the ANSI standards.
S & C (for circuit switchers, anyway) doesn't follow standards set by an independent body. S & C finds a niche for products that don't fit the ANSI world, thus giving them a proprietary product that is difficult to specify for competitive bidding and more often than not leading to sole sourcing. It's a brilliant marketing strategy to eliminate the competition. If the customer doesn't require the assurance of ANSI, then buy S & C. In my experience, the S & C circuit switchers are only marginally cheaper than an ABB ANSI-rated live-tank breaker (HFD or LTB).
Having said all that, I have used S & C products several times in the past (usually fuse gear) and agree with Mark that they have a good reputation.
RE: Circuit Switcher vs. Circuit Breaker
Redtrumpet, how did that 8kA compare to your maximum available fault current?
One legitimate use of a low rated CS would be on the source side of a delta wye transformer with restricted earth fault protection on the low side. Internal faults on the low side would be cleared by the switcher, while high side faults would be cleared by remote line protection. No attempt by CS to clear the high side internal fault.
RE: Circuit Switcher vs. Circuit Breaker
RE: Circuit Switcher vs. Circuit Breaker
In the example I gave above, CS would be required to make the full available fault current at its terminals, (darn, forgot those grounds again) but would only be required to interrupt the transformer impedance limited current from the restricted earth fault.
RE: Circuit Switcher vs. Circuit Breaker
Circuit switchers are not as capable as circuit breakers, but that is often not the right comparison. Circuit switchers are typically used on distribution transformer primaries where fuses were typically used in the past. Use of circuit switcher in place of fuses is a major improvement in protection. For most of these applications, there is no way that the cost of a 115 kV or 230 kV circuit breaker could be justified.
Circuit switchers have a long history of successful application and I suspect that they will co-exist with circuit breakers (and fuses) for a long time to come.
RE: Circuit Switcher vs. Circuit Breaker
dpc - I didn't mean to create the impression that circuit switchers are unusual. I know they are used extensively by utilities. I work in private industry, however, and the circuit switchers I was involved with were installed by an institutional client (university) that subcontracted with the local utility for its substation maintenance. Non-utility clients are often less sophisticated than a utility and may not know the limitations of a circuit switcher. If you are not a utility, I believe you should know these are not ANSI-rated devices. The Mk V circuit switcher cost us about $80k Canadian. An ABB LTB ANSI-rated breaker would have been about $90k Canadian - not a huge difference for a more capable device.
However, in our application the S & C circuit switcher was adequate, the client understood what they were getting, and we used it.
Not everyone in these forums works for a utility and the needs of the non-utility client have to be understood as well.
RE: Circuit Switcher vs. Circuit Breaker
RE: Circuit Switcher vs. Circuit Breaker
So, the circuit switcher is quite a bit cheaper in the end.
RE: Circuit Switcher vs. Circuit Breaker