# good idea?



## sparky970 (Mar 19, 2008)

Saw some guys replacing brushes on this today. Don't know if it was generating, but it was running. Is this a bad idea?


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## B4T (Feb 10, 2009)

It must of been done to manufactures SOP or the guys must of missed all the PPE classes..


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## Theriot (Aug 27, 2011)

sparky970 said:


> Saw some guys replacing brushes on this today. Don't know if it was generating, but it was running. Is this a bad idea?


It's not a generator it an ice cream machine.


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## erics37 (May 7, 2009)

Is it a steam turbine generator of some sort?

EDIT: Or diesel or something?


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## TOOL_5150 (Aug 27, 2007)

erics37 said:


> Is it a steam turbine generator of some sort?
> 
> EDIT: Or diesel or something?


I can tell you for sure, it is definitely something.


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## HARRY304E (Sep 15, 2010)

TOOL_5150 said:


> I can tell you for sure, it is definitely something.


Yes it very well could be..:whistling2:


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## MDShunk (Jan 7, 2007)

That's an oldie too. I've seen pretty much that same generator in blue and green. Both from the mid 50's.


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## mrmike (Dec 10, 2010)

sparky970 said:


> Saw some guys replacing brushes on this today. Don't know if it was generating, but it was running. Is this a bad idea?


It is a steam turbine generating voltage probably supplying electricity for the whole plant.

It is one like we had in our plant where I worked. Ours produced 13,800 volts. We had to check & change brushes on it weekly-& yes while it is running. I can't remember what the field voltage was but There were many brushes on it, & lifting one & replacing one was no problem using High voltage gloves. We also had to "brush" the rotor on it, cleaning it...........


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## Big John (May 23, 2010)

The voltage on those is probably less than 200DC. 

Yeah, it gets done, but unless the thing never goes offlines, it's not necessary and increases the likelihood of an outage if someone drops a brush or something.

Besides which, I don't know what kind of short-circuit current is on that exciter, but I'm betting you wouldn't want to have your face in front of it.

-John


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## Zog (Apr 15, 2009)

I used to have to do the same thing on our generators on the sub, always scared the crap out of us, dangerous as hell.


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## MDShunk (Jan 7, 2007)

Generator guys:

How many brushes can you lift before the brush liftoff relay trips out?

Can you tell from looking at that pic whether it's a backpressure turbine or the condensing type? Hell, maybe that's not even a turbine. I just recognize the generator end.


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## nolabama (Oct 3, 2007)

mrmike said:


> It is a steam turbine generating voltage probably supplying electricity for the whole plant.
> 
> It is one like we had in our plant where I worked. Ours produced 13,800 volts. We had to check & change brushes on it weekly-& yes while it is running. I can't remember what the field voltage was but There were many brushes on it, & lifting one & replacing one was no problem using High voltage gloves. We also had to "brush" the rotor on it, cleaning it...........


would it spin your watch backwards?


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## nolabama (Oct 3, 2007)

Theriot said:


> It's not a generator it an ice cream machine.


mmmm ice cream mmmmmm


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## Big John (May 23, 2010)

MDShunk said:


> How many brushes can you lift before the brush liftoff relay trips out...?


 We actually don't use brush lift-off, because carbon tracking between the rings can mess it up.

We use an active field resistance monitor that still injects a signal and measures the return, but it's looking at the resistance between rings as well as from each pole to ground, so we end up getting ground-fault detection and short-circuit detection in the same device.

-John


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## anthonydavis4188 (May 16, 2012)

Ice-cream machine lol!


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## Legion (Oct 19, 2010)

sparky970 said:


> Saw some guys replacing brushes on this today. Don't know if it was generating, but it was running. Is this a bad idea?


It used to be standard practice to change brushes while online in power plants... and even done by _non-electricians_, I'm not sure what current policies are.


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## Lone Crapshooter (Nov 8, 2008)

I have changed the ones at work hundreds of times. We have a special tool that you stick in the brush holder and releases the brush and it comes out.

Our exciter voltage is about 250 volts and we have 8 brushes per ring.


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