# Transformer Dischargeing



## Dennis Alwon (May 9, 2009)

I have no idea but I wouldn't do it the way dad did.  :laughing:


----------



## guest (Feb 21, 2009)

First off, transformers do not store voltage so why would you want or need to "discharge" it? :whistling2:

Second, throwing a chain at ANY equipment is dumb, if it happened to be energized you'd end up with a series of molten grenades (the links) flying around. 

Now, if we are talking about safety grounds for protection while working on equipment they make such things and are commonly used by POCO's for HV work. Here's a link to one of many companies:

http://burlingtonsafety.thomasnet.com/category/grounding-equipment

Chains are NOT an approved method of safety grounding and IIRC never have been. 

And even with safety grounds, you MUST follow proper LOTO procedures in any event....safety grounds can FAIL under sufficient fault current and cause greater hazards.


----------



## Morrison9493 (Apr 20, 2012)

Thanks for the input. In my Dads defense, He's 75 years old and that the way the "used" to do things, back when the code book was more like a pamphlet. I've spoken with our local utility workers, and they said to always ground it before PMing the thing, so YES i'm referring to maint. proceedures:thumbsup:.


----------



## jza (Oct 31, 2009)

How can someone have such limited knowledge of electrical theory to think that a transformer needs discharging. Are you an electrician?


----------



## Morrison9493 (Apr 20, 2012)

jza said:


> How can someone have such limited knowledge of electrical theory to think that a transformer needs discharging. Are you an electrician?


 
YES I'M AN ELECTRICIAN! 3rd generation. My employer is requireing such a practice. No I've never heard of it being done before, THATS WHY I'M ASKING IF YOU HAVE!


----------



## Dennis Alwon (May 9, 2009)

guys just answer the question or state that no discharging is necessary. I had never heard of it either however they may have something there the op is not mentioning. Capacitors in the circuit would hold a charge. Are you sure that is not what you have.


----------



## Morrison9493 (Apr 20, 2012)

Dennis Alwon said:


> guys just answer the question or state that no discharging is necessary. I had never heard of it either however they may have something there the op is not mentioning. Capacitors in the circuit would hold a charge. Are you sure that is not what you have.


 
No, this is general maint. @ multiple schools sites. My employer is requesting it be done this way, by way of our safety officer.


----------



## Zog (Apr 15, 2009)

jza said:


> How can someone have such limited knowledge of electrical theory to think that a transformer needs discharging. Are you an electrician?


Actually they will hold a charge, the insulation of the windings has capacitive properties. Nothing I would worry about for something this small but you bet I ground both sides before working on a 50MVA 69kV/13.8kV transformer.


----------



## Big John (May 23, 2010)

I don't know how big a primary 480V transformer would have to be before I'd worry about capacitance, but I've never seen it.

Grounds are pretty exclusive to medium and high voltage.

-John


----------



## Amish Electrician (Jan 2, 2010)

I note that in another thread, one of the long-time members has trouble telling 'induction' from 'convection.' Could the OP be really asking about capacitors?

BTW, Zog ... some time ago you posted a pic of a tool for discharging capacitors. Oddly enough, since that time I have had to deal with some such capacitors, and the gizmo has come in handy.

I got a kick out of the maintenance guys who said "why bother?" ... then had a bit of a flash a few days later. 20 years running, never needed it ... I must have ahd six different folks at that company calling me and asking for the source.

http://www.cementexusa.com/pdf/CCDT.pdf


----------



## Southeast Power (Jan 18, 2009)

Morrison9493 said:


> Hey all,
> 
> I have a question regarding the proper proceedure for dischargeing a 480v-208 3 ph. transformer for the purpose of Pm'ing them. My father used to throw a truckers chain at'em a step back. I can't find anything on the web about it, and I've never had to do it before. Where I work is REALLY BIG on safety, otherwise I wouldn't worry about it. Also, is there a manufactured grounding strap for this? Thanks for ANY help:confused1:


The safe procedure or a small transformer you have would be LOTO. If you were concerned about a discharge then simply turn on a load after you de-energize it.


----------



## Morrison9493 (Apr 20, 2012)

Again,

I am the OP. I have worked with transformers for many years. I'm not talking about capacitors! I was wanting to know if you guys had ever heard of such a thing. I didn't join to be critisized by my fellow tradesman. I thought this was a "resourceful" exchange of knowlegde, not a roast!


----------



## Southeast Power (Jan 18, 2009)

Morrison9493 said:


> Again,
> 
> I am the OP. I have worked with transformers for many years. I'm not talking about capacitors! I was wanting to know if you guys had ever heard of such a thing. I didn't join to be critisized by my fellow tradesman. I thought this was a "resourceful" exchange of knowlegde, not a roast!


It's kinda like the local bar here. I think they like you, they haven't gone after your spellin yet..


----------



## nolabama (Oct 3, 2007)

I have never ever ever heard of discharging a small secondary transformer. Having said that safety nazi wants something they generally get it. I would get a primary ground clamp and install/ground the hv side and then install a #6jumper with alligator clamps between the secondary grounding and where the phase ties in. Then tell your safety guy he is an idiot and his mother is a whore.

Your safety nazi is likely confusing the discharge of primary transformers with the tool that the amish sparky sent a link on ( I think he uses the diesel electricity so thats aok) with the need to discharge the secondary transformers.


----------



## HARRY304E (Sep 15, 2010)

Morrison9493 said:


> Again,
> 
> I am the OP. I have worked with transformers for many years. I'm not talking about capacitors! I was wanting to know if you guys had ever heard of such a thing. I didn't join to be critisized by my fellow tradesman. I thought this was a "resourceful" exchange of knowlegde, not a roast!


Welcome to the forum Morrison 9493.

Remember you are dealing with your fellow tradesman who are Electricians and men,,,put ten men in a room and things can get rough.

In your first post you said that "your father used to throw a truckers chain at'em a step back to discharge a transformer"

I can say that, That is a very dangerous thing to do and would not recomend it any time.

In fact I never heard anything like that at all and thought you were joking.

If you could post the type and voltage of the transformers that you are working on I'll bet that you will get the correct answer on how to shut them down and make them safe so you can do your PM's on them:thumbsup:


----------



## Zog (Apr 15, 2009)

Morrison9493 said:


> Again,
> 
> I am the OP. I have worked with transformers for many years. I'm not talking about capacitors! I was wanting to know if you guys had ever heard of such a thing. I didn't join to be critisized by my fellow tradesman. I thought this was a "resourceful" exchange of knowlegde, not a roast!


Hey I am trying to help you here. And so are other guys, ignore the pipe benders, this is a tough room sometimes.


----------



## crazy electrician (Apr 30, 2011)

Amish Electrician said:


> I note that in another thread, one of the long-time members has trouble telling 'induction' from 'convection.' Could the OP be really asking about capacitors?
> 
> BTW, Zog ... some time ago you posted a pic of a tool for discharging capacitors. Oddly enough, since that time I have had to deal with some such capacitors, and the gizmo has come in handy.
> 
> ...


 What kind of tool are you talking about and why would you need it? I just short out the terminals with a screwdriver.


----------



## RIVETER (Sep 26, 2009)

Morrison9493 said:


> Hey all,
> 
> I have a question regarding the proper proceedure for dischargeing a 480v-208 3 ph. transformer for the purpose of Pm'ing them. My father used to throw a truckers chain at'em a step back. I can't find anything on the web about it, and I've never had to do it before. Where I work is REALLY BIG on safety, otherwise I wouldn't worry about it. Also, is there a manufactured grounding strap for this? Thanks for ANY help:confused1:


When it is off...it is OFF. Why would there be a reason to discharge it?


----------



## Big John (May 23, 2010)

RIVETER said:


> When it is off...it is OFF. Why would there be a reason to discharge it?


 I don't know that there is a reason for low-voltage. 

But you get into voltages above that, and it doesn't matter if it's off: It's not dead until it's grounded.

-John


----------



## CADPoint (Jul 5, 2007)

The first electrical trick is to coil something, but static grounding of terminals is done all the time by POCO's, go by any yard and there sitting there tapped together.

What's the big deal, Welcome to the Forum.


----------



## BBQ (Nov 16, 2010)

Big John said:


> I don't know that there is a reason for low-voltage.
> 
> But you get into voltages above that, and it doesn't matter if it's off: It's not dead until it's grounded.
> 
> -John


In the area of Westerly RI they have some 39kV distribution and before they work on a pad mount they pull the conductors off of the over head supply and ground them out.


----------



## BBQ (Nov 16, 2010)

Morrison9493 said:


> Hey all,
> 
> I have a question regarding the proper proceedure for dischargeing a 480v-208 3 ph. transformer for the purpose of Pm'ing them. My father used to throw a truckers chain at'em a step back. I can't find anything on the web about it, and I've never had to do it before. Where I work is REALLY BIG on safety, otherwise I wouldn't worry about it. Also, is there a manufactured grounding strap for this? Thanks for ANY help:confused1:


I work with these all the time and have never once done anything specific to discharge them. 

As has been mentioned if you are concerned just put a load on the secondary.


----------



## nolabama (Oct 3, 2007)

BBQ said:


> In the area of Westerly RI they have some 39kV distribution and before they work on a pad mount they pull the conductors off of the over head supply and ground them out.


It keeps them alive.


----------



## Zog (Apr 15, 2009)

jza said:


> How can someone have such limited knowledge of electrical theory to think that a transformer needs discharging. Are you an electrician?


Nice job insulting the new member when you have no idea what you are talking about. 

Are you an electrician?:laughing:


----------



## HARRY304E (Sep 15, 2010)

Zog said:


> Nice job insulting the new member when you have no idea what you are talking about.
> 
> Are you an electrician?:laughing:


He has not logged in since his last post


----------



## Mulder (Sep 11, 2010)

Zog said:


> Nice job insulting the new member when you have no idea what you are talking about.
> 
> Are you an electrician?:laughing:


Zog, of course you lockout and check to make sure what you are working on is deenergized,but at 480v do you discharge like the op is suggesting?


----------



## Big John (May 23, 2010)

Just because nobody does it, doesn't mean it's a stupid question. I've meggered large 600V stators at 1kV and seen them take several minutes to bleed down to zero volts after the voltage was turned off.

Maybe with a 480 transformer that was several MVA this might actually be a hazard? I dunno.

-John


----------



## Mulder (Sep 11, 2010)

Big John said:


> Just because nobody does it, doesn't mean it's a stupid question. I've meggered large 600V stators at 1kV and seen them take several minutes to bleed down to zero volts after the voltage was turned off.
> 
> Maybe with a 480 transformer that was several MVA this might actually be a hazard? I dunno.
> 
> -John


I didn't say it was stupid, I simply was trying to determine how many people actually do it.


----------



## Big John (May 23, 2010)

Mulder, that wasn't directed at you, I was just thinking out loud.

-John


----------



## Zog (Apr 15, 2009)

Mulder said:


> Zog, of course you lockout and check to make sure what you are working on is deenergized,but at 480v do you discharge like the op is suggesting?


Can't say I have ever worked on a 480/208V transformer, smallest I have ever touched is a 4160/480V maybe 500kVA and yes, I discharged it because it is in our ESWp's to do so. 

But Jza was insulting the OP based on theory and questioning if he was even an electrician for thinking about it when Jza is the one who should be reviewing his transfromer theory. :whistling2:


----------



## Zog (Apr 15, 2009)

HARRY304E said:


> He has not logged in since his last post


I don't blame him


----------



## wildleg (Apr 12, 2009)

I blame him. who else can log in for him ?


----------



## jza (Oct 31, 2009)

Zog said:


> Can't say I have ever worked on a 480/208V transformer, smallest I have ever touched is a 4160/480V maybe 500kVA and yes, I discharged it because it is in our ESWp's to do so.
> 
> But Jza was insulting the OP based on theory and questioning if he was even an electrician for thinking about it when Jza is the one who should be reviewing his transfromer theory. :whistling2:


You said it yourself, most transformers don't need to be discharged. I was assuming anyone working with a transformer big enough to required discharging wouldn't be talking about throwing chains at them.


----------



## Mulder (Sep 11, 2010)

Big John said:


> Mulder, that wasn't directed at you, I was just thinking out loud.
> 
> -John



No harm. I realize it wasn't at me, I just wanna know how the "big" guys do it. I have deenergized hv cable by grounding them out, but that was a long time ago. I am sure things have changed since then.


----------



## Hivoltage98 (Dec 17, 2010)

He should take a proper course on NFPA 70E safety and have formal training. This can spell out any bad practices and any false practices someone is asking him to do.


----------



## Zog (Apr 15, 2009)

jza said:


> You said it yourself, most transformers don't need to be discharged. I was assuming anyone working with a transformer big enough to required discharging wouldn't be talking about throwing chains at them.


No, you said "How can someone have such limited knowledge of electrical theory to think that a transformer needs discharging"

Based on "theory", all transfromers will hold a charge due to the design of the windings, but the smaller the transformer, the smaller the hazard. Before you go throwing insults around next time spend some time learning a little theory yourself.


----------



## Legion (Oct 19, 2010)

crazy electrician said:


> What kind of tool are you talking about and why would you need it? I just short out the terminals with a screwdriver.


Because you'd possibly be burnt alive doing that to some capacitor cells. We use a similar device to what they showed and still don proper PPE. Even if the cap cell or bank is designed to be self-draining upon being de-energized, there's no way of knowing that a fuse or connection hasn't deteriorated to prevent that from happening.


----------



## Amish Electrician (Jan 2, 2010)

Crazy Electrician:

The link I posted shows you the tool.

It differs from a screwdriver in that there is a resistor in the circuit; this lets the capacitor 'bleed down' over a few seconds, avoiding any damage a big spark might do to the finish of your heirloom-quality Commercial Electric tools. :laughing:

Mind you, there are capacitors, and then there are CAPACITORS. I use the tool with some caps that are part of a 400 amp, 900+ volt system. We're not talking Radio Shack stuff here.


----------



## mrmike (Dec 10, 2010)

Morrison9493 said:


> Thanks for the input. In my Dads defense, He's 75 years old and that the way the "used" to do things, back when the code book was more like a pamphlet. I've spoken with our local utility workers, and they said to always ground it before PMing the thing, so YES i'm referring to maint. proceedures:thumbsup:.


 
Coming from a Industrial background we covered just about everything including transformers. We never had to discharge 480 volt or less transformers when we P.M. d them. We just checked & torqued connections on a shutdown,without grounding them.

We had a lot of 13.8 kv transformers that we p.m d on a weekly basis for checking the oil level, etc. in TRANSFORMER STATIONS....

On a shutdown, we Would Check connections on these, & meggared everything, which was a tedious job as we removed all the bolts & cleaned the busses & then re-attached them & torqued them down. BEFORE doing all this, WE used grounding sticks from the connections to the Ground cable going to the grid, before working on any of them................................. Safely Discharging them of any stored voltage that could harm us...........

Wow, what old memories, this usually was an overnight thing on 11pm to 7am shift..........Long night...........

So Yes, if it makes you feel safer, even with 480v xfrm's, use a grounding stick from connections to ground. Usually a grounding stick is fiberglass with a cable & clamp........... Use the proper H.V. rated gloves to do this.................... there should be a step procedure wrote up to go by........................


----------



## jza (Oct 31, 2009)

Zog said:


> No, you said "How can someone have such limited knowledge of electrical theory to think that a transformer needs discharging"
> 
> Based on "theory", all transfromers will hold a charge due to the design of the windings, but the smaller the transformer, the smaller the hazard. Before you go throwing insults around next time spend some time learning a little theory yourself.


I'm well aware of the capacitor like properties of a winding, thanks. Please don't let our little argument make you leave the board again, LOL.


----------



## Zog (Apr 15, 2009)

jza said:


> I'm well aware of the capacitor like properties of a winding, thanks. Please don't let our little argument make you leave the board again, LOL.


Then why would you say "How can someone have such limited knowledge of electrical theory to think that a transformer needs discharging"?

You are just covering your tracks and you know it. You owe the OP an apology, but he left and went to Mike Holts forum where guys like you get booted.


----------



## nolabama (Oct 3, 2007)

I did not know transformers acted like capacitors. I have been told to ground HV before touching it. Seemed reasonable enough for me. How much of a charge can a little secondary voltage transformer hold?


----------



## jza (Oct 31, 2009)

Zog said:


> Then why would you say "How can someone have such limited knowledge of electrical theory to think that a transformer needs discharging"?
> 
> You are just covering your tracks and you know it. You owe the OP an apology, but he left and went to Mike Holts forum where guys like you get booted.


lmao hahahah


----------

