CO-9 over current relay

[mikeengurs]

I have a feeder with CO-9 relay I'd like to coordinate with downstream breakers. The time delay element is adjustable, but the instantaneous element (IIT) is the problem. Does anyone know if we can add a timer to the IIT element? How is that done?

 

[oldfieldguy]

That function isn't part of the relay. You could add an outboard time delay relay.

old field guy

 

[DTR2011]

for the cost of adding an outboard timer, you may want to consider a drop in replacement for the CO-9, which is digital and has this and many other functions incorporated.

 

[cranky108]

Might check with Basler for in the case replacments. They might have time delays on the 50 function.

 

[Zogzog]

The Basler replacements are popular and a easy solution. I have a pile of these if you have a hard time finding them.

http://www.basler.com/html/be1retrofits.htm

 

[mikeengurs]

Thanks guys! Basler replacement relays are good options. Is there an advantage of using new relays, instead of just adding an external time delay elements (other than much more features maybe)?

 

[JG2828]

There are no moving parts, its easy to change settings, calibration will not drift over time, etc.

 

[DTR2011]

Add to JG2828's comments.

The skill sets to maintain and calibrate old devices is diminishing. Ordering replacement parts is costly. Once understood, a digital relay is much easier to test.

A digital relay has a digital file containing the settings. I don't know how many times I have come across EM relays where finding a paper trail for the settings is next to impossible.

A digital relay can communicate metered values. A digital relay has fault and event records.

A digital relay can utilize setting changes for Maintenance / Arc Flash mitigation.

The Basler is a nice solution, for nearly plug and play operation. The Basler design does have integral provisions for a test paddle. If you choose another Relay manufacturer, please do not forget test switches. I think ABB (US) has a version for adapting a CO relay with the FT switch built in.

 

[cranky108]

smallgreek, While the Basler retrofits are solid-state, they are not microprocessor (at least not in an I/O since).

But you make a good point about switching to newer relays.

And ABB did have a version for replacing CO relays. I don't know if they still offer them.

 

[DTR2011]

Cranky,

You are correct. I was thinking of the Basler 851 Series, which are digital and fit into the CO case. The BE 50/51B, I believe are the single phase replacements (SS).

 

[ScottyUK]

When considering the relative advantages and disadvantages it's worth remembering that there are electro-mechanical relays still in active service on the network which were installed long before the transistor was discovered. I love the flexibility of the microprocessor relays, but I'm absolutely sure they won't last as long their predecessors.

I also think the new relays are responsible for over-protection (the temptation to use every function 'because it is there'), and for dumbing down the subject to the majority of users by taking away much of the complexity of a traditional scheme. Perhaps the latter is good for those of us who have to deal with protection as one of the many things we need to have a decent working knowledge of without ever getting the chance to become an expert in the subject.


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If we learn from our mistakes I'm getting a great education!

 

[oldfieldguy]

Scotty & Smallgreek-

Ah, the pros and cons.

Electromechanicals. I know it can be a hunt to find documentation for the settings, but you can look in the window and SEE the settings. Repairs? I've serviced thousands. Repairs are few and far between and can be accomplished by a guy with reasonable mechanical skills and simple (though small) hand tools. I never had to worry about the firmware version on a CO relay.

Microprocessor-based... Aside from flexibility, one term: "Fault records". Access to MORE information after a fault has kept me from scratching my head in all too many cases.

I started out on CO's and IAC's,, and they're great equipment, but please don't make me go back.

Mike-

If it's an option, you REALLY ought to look at upgrading to something like a GE SR350 or something in that capability range.

old field guy

 

[mgtrp]

I'd take the numerical relay if I could. There are numerous relays that fit in a CO9 footprint - SEL, Basler, GE, etc - but a numerical relay would usually be best.

With regards to adding a timer to an instantaneous element - of course this can be done when the instantaneous element is brought out as a separate contact (from memory, this is the case for a CO9) but this isn't usually desirable for an instantaneous element as it adds additional unreliability.

 

[cranky108]

Scotty, so true.
I have been acused of not using microprocessor relays to there full capability. For which I responded, "do you really need sync-check on every distribution circuit. And by the way when are you going to install the PT's for that".

If you go with microprocessor relays, keep the settings simple, and only use what you need.

I haven't used a Basler relay in several years. They sort of got off on the wrong side here.
And I rarely use GE relays because one I don't like there sales people, and another they obsolete there relays to quickly for me.