LOTO - takes too long??

Apparently some one did not do a correct LOTO

Here is result. Now that is what I call a dmaged commutator.
If anyone has any good pictures of DC equipment damage like this I sure would like them.

State Ferries think they MAY have a spare. GE will take two years to build a new one.

That is all teh info I have and it is from media.

See at
http://www.nwcn.com/news?fId=177937191&fPath=/news/local&fDomain=10212

leitmotif said:

Apparently some one did not do a correct LOTO

Here is result. Now that is what I call a dmaged commutator.
If anyone has any good pictures of DC equipment damage like this I sure would like them.

State Ferries think they MAY have a spare. GE will take two years to build a new one.

That is all teh info I have and it is from media.

See at
http://www.nwcn.com/news?fId=177937191&fPath=/news/local&fDomain=10212

Click to expand...

Wow Dan, that is a huge amount of damage. It is hard to believe they would miss a simple step like LOTO when their life was on the line. They are incredibly lucky no one was killed or seriously injured.

They are saying up to two years and millions of dollars to repair it. Ouch!

Stu....

There was speculation on another site that it may have been a locked rotor.

Used to repair commutators - have seen a few melts in my time but that one looks pretty big!
Be cutting new segments for a fair while to repair that one!

One of the problems with LOTO training I have seen is they rely on test running motor instead of going in and checking with meter. I think this is wrong.

If you hang the tag on the wrong breaker (I have seen this done a couple times) then yeah you did LOTO but you just may be getting into trouble here,,,,

In Navy we had a guy shut the output breaker on a 250 VDC diesel generator when it was shutdown. It turned the generator and engine over but there was no damage to the commutator. Oh yes that breaker tripped allright.

I theorize that even if they did shut the breaker on a stationary motor it would not have harmed it. Tbat is assuming the motor and shafting do not have jacking gear like those on steam turbine setups. This unit was undergoing maintenance so who knows what was disconnected or laying on frame and creating a short or what. One thing for sure that commutator is nearly beyond salvage.

Anybody in a repair shop have some good photos of badly damaged commutators - I need them for electric vehicle training program. Oh yeah - please.
Dan Bentler

Dan,

I have quite a few ranging from 75HP-4000HP, let me dig them out for you.

nic00 said:

Dan,

I have quite a few ranging from 75HP-4000HP, let me dig them out for you.

Click to expand...

Since this is for Electric Vehicles - mostly automotive - 75 HP "range" would be most appropriate. Bigger would not hurt though.

Thanks for the help

Dan Bentler

leitmotif said:

Since this is for Electric Vehicles - mostly automotive - 75 HP "range" would be most appropriate. Bigger would not hurt though.

Thanks for the help

Dan Bentler

Click to expand...

May be a big electric vehicle ^_^ weighing circa 120T

the LOTO procedure may have been flawed a bit.
'Wrong Breaker Operated'
I have found it amusing when attending some companies manditory LOTO training. Having an Up to date HV ticket - these companies are still nowhere near that LOTO -
A Written permit to access specific HV switch gear and the clear marking associate 'UNDER ACCESS PERMIT' and 'LIVE' equipment is a requirement.
I think the OSHA groups need to do a restudy of the LV systems

Dan,

Please see attached images of a 100HP Shunt motor.

nic00 said:

Dan,

Please see attached images of a 100HP Shunt motor.

Click to expand...

For sure things look over heated. Wild guess was this from flashover? My training was to concentrate on making things run right - they must have done well since I have never seen destroyed equipment like this.

What I have observed with hobby Electric Vehicle owner / self converters is they have heart attack when motor cost exceeds $2000 USA. So they buy what I think are undersized motors.
Sellers support this by marketing
60 HP -
then in fine print (peak) -- 15 continuous.

leitmotif said:

For sure things look over heated. Wild guess was this from flashover? My training was to concentrate on making things run right - they must have done well since I have never seen destroyed equipment like this.

What I have observed with hobby Electric Vehicle owner / self converters is they have heart attack when motor cost exceeds $2000 USA. So they buy what I think are undersized motors.
Sellers support this by marketing
60 HP -
then in fine print (peak) -- 15 continuous.

Click to expand...

A rectifier in the control circuit was kaput, which lead to the current limiting within the mag amp control not working. The increased current caused brushes to stick in the boxes which then resulted in a flashover.

Repair cost's on these machines are not cheap either!