Signage for sharing a feeder

[Mule]

Got a 400amp feeder that feeds one chiller or another one via closing one safety disconect or another. The feeder is not large enough to carry both chillers. There are controls that will not allow both to run. This building does have a engineering person on staff that will orchestrate the switching back and forth, but I want to put up a sign on the disconects...what should it say?

[Cow]

"Mule was here"

[Mule]

"Mule was here"

WHAT? You lost me

[Mule]

So, Im thinking something like....

LOTO proceedure for switching chillers:

Shut down running chiller and LOTO
Unlock other disconect and start chiller
"DO NOT ATTEMPT TO RUN BOTH CHILLERS"

I dont how else to word it.....

[Mule]

Come on guys? What should I put on this sign....? This is a back up chiller

[billsnuff]

i would label them chiller 1 and chiller 2. IMHO it is the employers responsibility to write the LOTO procedures and train their employees. although not your responsibility, i would give them your input and leave the rest to them.

[wireguru]

I would actually interlock the power with a reversing contactor or something so its impossible to power both. Or at least present the option to the customer. I can see some chiller repairman trying to run both........

[mkgrady]

I would actually interlock the power with a reversing contactor or something so its impossible to power both. Or at least present the option to the customer. I can see some chiller repairman trying to run both........

That's what I did where a customer had two compressors. The feeder was only big enough for one at a time.

Isn't it a violation to connect more load than the feeder can handle?

Isn't it just a matter of time before someone runs both chillers and overloads the circuit? I say this even considering you plan to put a sign up warning against this.

[iwire]

Got a 400amp feeder that feeds one chiller or another one via closing one safety disconect or another. The feeder is not large enough to carry both chillers. There are controls that will not allow both to run. This building does have a engineering person on staff that will orchestrate the switching back and forth, but I want to put up a sign on the disconects...what should it say?

There are controls that will not allow both to run.

As far as I can see there is no need to do anything more.

[Mule]

We recently did the installation and as stated, this is a "back up unit" and is not needed unless one or the other is broken down for repairs or scheduled maintenance. The feeder comes from 3floors down in the basement. The feeder has parallel 2/0's in 2 inch conduits that feed the line side of both of these disconects via a gutter connection . Then the load from each safety switch goes respectfully to its chiller which are setting side by side on the roof. They are interlocked via, logic, and a control voltage interlock which controls respective contactors. The "OFF" machine will be locked out as a extra pre-caution. I just thought I would install a sign for "Dummies" in case the appropiate folks are not around when they need to switch machines.

[mdshunk]

If the control circuit won't let them both run, just let both disconnects on and don't worry about it. Sorta along the lines of what Bob says. Even if they did manage to run both somehow, what's the worst that will happen? A breaker will trip someplace. No problem.

[Mule]

If the control circuit won't let them both run, just let both disconnects on and don't worry about it. Sorta along the lines of what Bob says.

It was a decision among the client and myself, that in the case of mishap and both did try to start and knock out the fuses during a performance (community center) that it would be some what disasterous to the event of the evening....So the lock out, is just a precaution. The key will be right there with instructions, which brings us to this sign...:smile:

[mdshunk]

It was a decision among the client and myself, that in the case of mishap and both did try to start and knock out the fuses during a performance (community center) that it would be some what disasterous to the event of the evening....So the lock out, is just a precaution. The key will be right there with instructions, which brings us to this sign...:smile:
I see..... why not install a double throw switch, rather than two disconnects, then?

[wireguru]

It was a decision among the client and myself, that in the case of mishap and both did try to start and knock out the fuses during a performance (community center) that it would be some what disasterous to the event of the evening....So the lock out, is just a precaution. The key will be right there with instructions, which brings us to this sign...:smile:

at some point, some stagehand guy who thinks he knows EVERYTHING because he is the STAGE MANAGER is going to monkey with this

'ill just get both chillers running so i can cool MY STAGE quicker - i have a 400a 3ph service to them so thats 1200 amps, and each chiller says 400 amps, so thats 800amps and ive got 400amps left i can tie some lighting dimmers into'

id spend the few hundered bucks on the contactor. set of fuses and a trouble call will pay for it.

[Mule]

I see..... why not install a double throw switch, rather than two disconnects, then?

That was my suggestion....but they were convinced by the other bidder...bla bla....So they wanted apples for apples bid..


and there's more ....this NEW chiller....is actually a skid unit that is TWO chillers, which has ANOTHER feeder that we extended from one floor down stairs which is a bit smaller 250kcmil.....SO the NEW chiller has TWO sources of power....Which will be a warning sign in its self....Trane designed this unit to utilize these existing feeders

[mdshunk]

That was my suggestion....but they were convinced by the other bidder...bla bla....So they wanted apples for apples bid..


and there's more ....this NEW chiller....is actually a skid unit that is TWO chillers, which has ANOTHER feeder that we extended from one floor down stairs which is a bit smaller 250kcmil.....SO the NEW chiller has TWO sources of power....Which will be a warning sign in its self....Trane designed this unit to utilize these existing feeders
This might be one really good application for a Kirk Key system, with this additional information. They can be adapted to pretty much any kind of enclosure, operating handle, etc. No signage necessary. You can't screw up.

http://www.kirkkey.com/index.html

[Mule]

at some point, some stagehand guy who thinks he knows EVERYTHING because he is the STAGE MANAGER is going to monkey with this

'ill just get both chillers running so i can cool MY STAGE quicker - i have a 400a 3ph service to them so thats 1200 amps, and each chiller says 400 amps, so thats 800amps and ive got 400amps left i can tie some lighting dimmers into'

id spend the few hundered bucks on the contactor. set of fuses and a trouble call will pay for it.

The contactors ARE in place...just down stream...and redundant contactors would be more than a few hundred bucks..

[Mule]

This might be one really good application for a Kirk Key system, with this additional information. They can be adapted to pretty much any kind of enclosure, operating handle, etc. No signage necessary. You can't screw up.

http://www.kirkkey.com/index.html

Is that those sequenced keys I see on switch gear to obtain access inside?

[mdshunk]

Is that those sequenced keys I see on switch gear to obtain access inside?
Uh-huh.... mostly I see them for main tie main's or on the grounding switch.

[Mule]

Uh-huh.... mostly I see them for main tie main's or on the grounding switch.

Well that a good idea, if they want to keep them locked out, I'll suggest that for sure...thanks.....If would just trust the logic which is in Tranes PLC I think it will be fine. There is NO function that will allow them put BOTH in manual and hit start...

[mdshunk]

There is NO function that will allow them put BOTH in manual and hit start...
Oh, ... that would be the root of the problem you're trying to prevent. I understand better now.

By the way, the Kirk stuff ain't exactly cheap, but it's probably the cheapest way I can think of that you can 100% prevent the problem at this stage of the game.

[Mule]

Uh-huh.... mostly I see them for main tie main's or on the grounding switch.

I remember now...I seen those locks on a var compensator that I helped to install. It had a ground switch....So you had to pull the unit OFF line. Then it allowed you to take a key out and unlock the ground switch, then after that was closed, it allowed you to remove another key and unlock the cabinet to get inside....

[wireguru]

The contactors ARE in place...just down stream...and redundant contactors would be more than a few hundred bucks..

oh yeah oops. 400amp reversing contactor is 1200-1500 something dollars....

[mdshunk]

oh yeah oops. 400amp reversing contactor is 1200-1500 something dollars....
The best figures I have show that's going to be closer to 5 grand.

[Mule]

The best figures I have show that's going to be closer to 5 grand.

I did the whole job for 9grand and made good money....

[mdshunk]

I did the whole job for 9grand and made good money....
So, you don't want to sell a 5K contactor as an extra? :smile:

[Mule]

So, you don't want to sell a 5K contactor as an extra? :smile:

Nope, I dont function that way......I work for the client