Generator Testing

[mickeyrench]

When testing a generator backup for a 480volt 4000amp. gfci service is the testing person suppose to be a quilfied employee and should he be suited up. Testing can be under a load or not under a load. Also the company policy says no work over 2* hrc. We have never racked out switch gear . We due remove buckets in mcc and according to 70e it a 4 on hrc task list.
Can someone point out the rules on these situations ?
Thanks

 

[zog]

When testing a generator backup for a 480volt 4000amp. gfci service is the testing person suppose to be a quilfied employee and should he be suited up.

You mean testing a GF system? Need to know exactly what they are doing but if they are properly testing a GF system yes they need to be qualified and wearing the roght PPE.

Also the company policy says no work over 2* hrc.

On a 4000A service you are going to be > HRC 2*, in fact chances are you are outside the limits of the tables and should be using the tables anyways so HRC's won't apply. The Ei needs to be calulated if you are outside the table limits and your Ei's will likely be very high (>40cal)

We due remove buckets in mcc and according to 70e it a 4 on hrc task list.

There are remote bucket extractors availble for this.

Can someone point out the rules on these situations ?
Thanks

Didn't your company just have 70E training or am I confusing you with someone else? Your training should have covered all of this, if not it obviously was not sufficient.

 

[brian john]

1. What kind of testing? Using site load and mainly operating an ATS or connecting temporary load load banks.
2. Is this done remotly from a control panel or are you in an ATS.

Need more information to give a meaningful answer.

 

[mickeyrench]

From what i can see the m.m. simulates a power failure and the gen is suppose to kick in. I ask the m.m. why he did not have ppe on and he said he is not reqired to . He said he is only operating a switch and not opening any doors.

 

[zog]

From what i can see the m.m. simulates a power failure and the gen is suppose to kick in. I ask the m.m. why he did not have ppe on and he said he is not reqired to . He said he is only operating a switch and not opening any doors.

Did he go through this training also?

Sounds like you have some serious issues there.

 

[mickeyrench]

You are correct Zog . We did have training ,a couple of videos and field test that consisted of showing us how to use a voltage tester. The instructor was not an electrician or a engineer . I asked him about the size of our service and that it might be out of the limits for the tables and he said that it was not.
I want to go to the plant manager but just don't know enogh about it to get it across. 4000amp 480v cb with a sd d digatrip 500rms module .
note 4 says that maximuim 35ka short cicuit available for fault clearing.
Our switch gear s s c is rated for 85ka. and the main bus is 100 ka. I believe this enough to be out side the table limits. But my thinking is that the digatrip unit on the cb might be keeping it below the limits in some way.
The tables say operating switchgear cb with the doors closed is an hrc 0 . is that true? Thats for all your time.

 

[zog]

You are correct Zog . We did have training ,a couple of videos and field test that consisted of showing us how to use a voltage tester. The instructor was not an electrician or a engineer .

That is just going through the motions, and p's me off.

I asked him about the size of our service and that it might be out of the limits for the tables and he said that it was not.

I bet $500 he has no idea if it is or not.

I want to go to the plant manager but just don't know enogh about it to get it across. 4000amp 480v cb with a sd d digatrip 500rms module .
note 4 says that maximuim 35ka short cicuit available for fault clearing.
Our switch gear s s c is rated for 85ka. and the main bus is 100 ka.

Just because your switchgear has a 85kA rating dosent mean you have >35kA available, but is a good clue you do. Someone spent the extra money for the higher interuption ratings for a reason.

I believe this enough to be out side the table limits. But my thinking is that the digatrip unit on the cb might be keeping it below the limits in some way.

It wont do anything to keep fault currents low, but depending on the available trip functions and thier settings it may keep your clearing times within the table limits. Post a picture of the trip unit so we can see the settings, or if you can't do that, post the settings.

Is this fed by a transformer owend by your company or a direct utility feed? If it is a transfomer post all the nameplate info, if not, you can call your utility to get the available fault current to your facility.

 

[mickeyrench]

I do have some other info on the square d digatrip rms 500 cat# t55 c15g.
The transformers are 6 - at 500 kva ea. own by utility co. primary is 13.5v.
the cb are sguare d type ds-840 power zon 111. thanks.

 

[brian john]

What is his exposure?

 

[mickeyrench]

e is at the panel and hits the test switch and gen runs for 20 min .I am not sure if he tuns switch back to on position. thats about it. he said the table calls for a hrc 0.

 

[zog]

I do have some other info on the square d digatrip rms 500 cat# t55 c15g.

That dosent help, we need the actual settings.

The transformers are 6 - at 500 kva ea. own by utility co. primary is 13.5v.

Are the 6 transformers all connected in paraell? What are the %Z values for each transformer?

 

[brian john]

So he goes to an ATS or a remote Annuciator and operates a toggle test switch?

 

[mickeyrench]

Zog, did not have a chance to get into trans. area today. I did get the info of the module on mainbreaker. all the numbers are in a box and "in " outside box.
1. long delay setting = 1.0 ln
2.long delay time = 7 sec @ 6 ln
3.short delay pickup= 3 ln
4. short delay time = .5 sec
5. gfi pickup = b ln
6. breaker trips 6t & gft test amps 3ln
7. gf time .5 sec
All the building feeds had one of the settings set at 24 , Ithink it was the long delay . Thanks again

 

[zog]

Zog, did not have a chance to get into trans. area today. I did get the info of the module on mainbreaker. all the numbers are in a box and "in " outside box.
1. long delay setting = 1.0 ln
2.long delay time = 7 sec @ 6 ln
3.short delay pickup= 3 ln
4. short delay time = .5 sec
5. gfi pickup = b ln
6. breaker trips 6t & gft test amps 3ln
7. gf time .5 sec
All the building feeds had one of the settings set at 24 , I think it was the long delay . Thanks again

With your six 500kVA transformers feeding a single 4000A breaker, assuming Z=5% for your transformers you have about 72,170A of available fault current comming into that gear.

Your arc flash currents will be somewhere above 27,424A and less than the 72kA.
Your breaker does not have an INST trip function, so you will have a time delay in an arc flash event that will cause Ei to be way higher than if you had Ei.

There is no way, based on the info you have posted, that this equipment is within the limits of the tables and your facility is required per the NFPA 70E to do an arc flash analysis.

Now there is a simple solution, you can retrofit your breaker you described above with an arc flash reduction switch, like the Quick Trip system from Utility Relay. Basically what it does is allow you to flip a switch and have "maintenence setting" on you trip unit, we do several of these every day and have seen most results reduce arc flash HRC's from 4 or dangerous, to 1 or 2 with the switch on.

 

[mickeyrench]

zog, first I like to thank you for your time , I plan on going to the pm and give him the information and hopefully he will do the right thing. Because if something like an accident should happen it can't be said "I did'nt know".
I mention it to a couple of my bosses and all that is said is " I don't know anything about that ". I sometimes wonder if I should just go about my business and say nothing.
Again thanks for your help and if something comes about this I let you know.

 

[zog]

zog, first I like to thank you for your time , I plan on going to the pm and give him the information and hopefully he will do the right thing. Because if something like an accident should happen it can't be said "I did'nt know".
I mention it to a couple of my bosses and all that is said is " I don't know anything about that ". I sometimes wonder if I should just go about my business and say nothing.
Again thanks for your help and if something comes about this I let you know.

OK, I just did some quick calcs using some assumptions, maybe one of the other guys with some software handy can check my math (Did it long hand). But I think you have a good arguement. If you look in the back of the 70E you will see some basic fault current calcs. FYI, your 0.5 ST delay means the breaker will trip in about 0.5 seconds at 6X the ST pick up, so for your breaker that is a 0.5 Sec delay for a 24,000A fault.

 

[mickeyrench]

Zog, I spoke to my m. m. today and he spoke to the pm about our service could be out of limits of the tables and the plant manager sounded very concerned. He plans to call and get some answers to the way this has gone. He wants me to write done the problems so he can ask the questions to the people who are "company people" about this situation. He said he is committed to getting it right. Hopefully he does.

 

[zog]

Zog, I spoke to my m. m. today and he spoke to the pm about our service could be out of limits of the tables and the plant manager sounded very concerned. He plans to call and get some answers to the way this has gone. He wants me to write done the problems so he can ask the questions to the people who are "company people" about this situation. He said he is committed to getting it right. Hopefully he does.

Sounds good, good luck. Let us know what happens.