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Rotary Switches In New Substations

Rotary Switches In New Substations

Rotary Switches In New Substations

Is there any benefit to ditching rotary switches in substations and letting relay push buttons and LCD mimics do the HMI?

Also, what is the typical way one goes about blocking close with rotatory switches if both primary and secondary relays happen to be disabled or unarmed?

Looks simpler without all these >>>

RE: Rotary Switches In New Substations

Are they lockable with padlock?

Best Regards A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: Rotary Switches In New Substations

As discussed in https://www.eng-tips.com/viewthread.cfm?qid=448754, there are both benefits and as problems to eliminating rotary switches.

What do you mean by blocking close? Do you mean adding wiring interlocks to prevent an operator from using a manual rotary switch to closing a breaker with both relays disabled? I had never considered that particular failure mode.

RE: Rotary Switches In New Substations

When I was younger, I was all for reducing panel footprint and using push buttons or an HMI. The longer I have been in the game the more I think that it is a bad idea or an idea with few benefits. SEL and other relays claim to be able to mechanically lockout devices and for some of their contact switches to retain position on power failure but I don't see anything that is as straight forward as a physical contact being open or close. It is the standard way of doing things. Lockout and tagging it out is similar to all other equipment. I would feel comfortable betting my life on the device not failing. I know it can be done other ways but I am unsure if the benefits outway the risk. I could see it for maybe low voltage equipment that it isn't a big deal if it misoperates, like small pumps. I don't know. It feels like a solution in search of a problem. I don't know if space is much of an issue due to the fact that you want equipment segregated if you can so when you have maintenance you aren't taking out two lines or two seperate pieces of equipment at the same time. That said, I have seen substations that went all the way with 61850 and they look very clean.

RE: Rotary Switches In New Substations

I think you have to distinguish between control switches and lockout relays. The main benefit to eliminating control switches is reduced cost and simpler wiring. IMO, lockout relays still serve a valuable function that cannot be directly equaled in digital relays.

RE: Rotary Switches In New Substations

For control switches, I think it depends on the process. I would be more conservative the more expensive or dangerous the process is. If a station was dark, it would be very nice to be able to operate the breakers or whatever without needing the relays. One part that I think needs to be taken into consideration is what if your relay or HMI fails, are you ok with not having control or jumpering connections until you get the equipment replaced?

RE: Rotary Switches In New Substations

We always build our applications so that they can be run without the HMI, I can even remove it while the machine is running nothing happens.
But we do not have any manuell switches for the same functions.
If the HMI breaks and we can't replace it straight away, we can always drive by manipulating signals online via PLC.
All mayor and security/safety funktions which are many, are still mechanical switches.
You can't have that kind of functionality through a standard HMI it's not allowed.
There are some brands that has safety functionality on mobile HMI though.


“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: Rotary Switches In New Substations

@Bacon4Life: Thanks!

Yes, preventing manual breaker closure with both protection relays disabled.

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