Circuit breakers vs Reclosers

[linehand]

Just curious if anyone out there has a similar system? We are a small utility and buy our power from a larger. Two feeds, one on each end of town. 34.5kv sub transmission looped to feed 7 substations. I am looking to replace antiquated OCBs with something simple and more modern. I see many mfg of 38kv reclosers.Our current breakers are 1200a 19000 short circuit. These are fed from a subststion tx owned by the company we buy from. Looks like the reclosers are rated to handle what we have. Is there any reason why I simply couldn't put these lower cost reclosers in place of the breakers? Just need to have a remote open/close switch away from the recloser.
Also if these will work, I'm thinking why not use similar reclosers 2 per sub feed to replace ancient air break switches with electro mechanical controls?

 

[amurray]

Hi Linehand,

We have seen issues/failures with reclosers & associated controls used in a substation application. Though these have only been a few cases so I can't make any across the board assumptions we are more comfortable with using circuit breakers & relaying in substation applications. We have worked with some municipals that replaced the recloser with circuit breakers after having issues. I am sure the cost of the reclosers compared to circuit breakers & relaying is attractive, but they just don't seem to perform like circuit breakers.

Hopefully others here can give you their experience.

 

[dpc]

We see reclosers used in small rural distribution substations in place of circuit breakers quite often. They are generally less expensive. The main concern is the interrupting rating. Historically, the reclosers had lower fault ratings than circuit breakers so their use in large substations was not possible. Modern equipment has higher ratings, but breakers are still more robust the reclosers in general. Also, breakers have much higher continuous current ratings - typically 1200 A versus 600 A (or 560 A) for reclosers.

I prefer breakers, but they can be a tough sell. A lot of investor-owned utilities are using metal-clad switchgear to reduce substation size and costs, so reclosers are not an option in this type of design. Most linemen don't like switchgear - they think it is less safe.

dpc

 

[HornTootinEE]

Linehand-

I've used reclosers in many distribution substation applications and never had an issue with them. But that was at 12.47Y kV. I've heard of other utilities around me using reclosers at the 25 kV voltage with success as well. Again, it's going to depend on your full load rating needs and also your interrupt rating. I know you can get reclosers that push the 20,000A interrupt rating, but 12,000A interrupt is very common. The ones I'm familiar with are the Cooper NOVA/NOVA-TS with the Cooper F6/F6-TS control, or the G&W Viper/Viper-ST with the SEL-351R or 651R controls. Both those units come in several configuration options including the ability to put the control in a control house if you wish. The highest full load amp rating I've seen on them though is something like 800A, which may or may not be an issue for you. Here where I live (ND), even the IOUs around here don't go much over 400A on a single circuit.

The hydraulic reclosers (traditional reclosers)had low interrupt ratings (<6000A) and pretty low full load amp ratings. You can still get that type of unit if you want as a line recloser. Wouldn't put that type of unit in a Substation ever-even though it was done in the past at my previous place of employment. Some of the old timers argued to keep using them-I threw a fit. haha

I know ABB and Siemens also make a "recloser" as well. I'd check into their offerings also. Rumor has it the Siemens now is carrying the SEL-351R control after trying to build there own?? Not sure. But I have personally had much success with the G&W and Cooper offerings in a substation application.

 

[mgtrp]

We use reclosers quite a lot in substations in our distribution system, safe with the knowledge that our available fault currents are very low (at times, they border on the continuous load current of the recloser...).

One issue that we have run in to from time to time is that many reclosers are line-powered, which means that you must have voltage on one particular side in order to close. This means that you can't energise the substation from the feeder, and also can't do testing so easily. Low-voltage close coils are often more suitable for substation applications.

 

[jghrist]

One advantage of reclosers over breakers in substations is the ability to have single-phase tripping. This can reduce the number of momentary outages by tripping only 1/3 the customers for a temporary fault. Permanent faults will lockout three-phase. Fast reclosing after a single-phase fault and trip will allow most three-phase motors to ride through the momentary interruption. Contactors would drop out for a three-phase trip.

If the available fault is limited to 10kA, then the recloser interrupting rating is adequate. Loadbreak elbows and most distribution cutouts are limited to 10kA, so you generally have to limit transformer sizes and/or impedance to keep faults below 10kA.

If you use line regulators, this will be the limiting factor for load current, not the 560A or 800A recloser rating.

 

[Mbrooke]

There is no reason why you could not use a recloser in place of a breaker. As long as the new reclosers are capable of handling the fault and continous current conditions that will be encountered on your system they will function without problem. Many Utilitys including ours use pole mount reclosers on subtransmission circuits for providing a second source to factorys, mid-point sectionalizing and the like.

Nearly all new reclosers are controlled electronically via pole mount cabinet that can easily be outfitteted with remote communications and switching ability.

Replacing the air-break switches with reclosers for me would be a no brainer investment. The responce parameters from the elctro-mechanical relays can be easily be transfered to the recloser control. Loop scheme logic (assuming its not already there) can also be progamed in to automatically give each sub 2 sources, ie a faulted line can be isolated automatically between the substations with no prolonged outages. Up North this has also helped us out with problems found in open air break switches like animals climbing over them.

 

[linehand]

Excellent information in these posts. Thank you.