This Happened Today!

PLC Pie Guy

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Jun 2013
Location
Halifax
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We had several power failures today, the power was off and on a couple times by the time we got around to all the equipment and got the mains disconnected.

After power was restored hours later we go into startup and recovery mode. All was good throughout the plant with the exception of one safety relay that didn't want to reset and had to be replaced, as well as one breaker that supply's a VFD on a conveyor.

I reached in and reset the breaker. BANG!!!! about 2' from my face this drive blows like a shotgun! Luckily, the worst injury I got was scraping my arm on the cabinet as I was doing a backwards commando dive in reaction to the blast!

At the time, I just kept going, replaced the drive and did what I had to do. Once I left work yesterday, I started thinking how lucky I was that the drive didn't completely blow apart and cause serious injury.

This is a 2011 MFG. Powerflex4M that was running on 460VAC.

Wear you PPE kids, and play safe!

IMG_3033.JPG IMG_3034.JPG
 
So here is my "Wear your PPE" story...

We were missing a spare drive, so we replaced the drive with a higher HP drive. To get that to work, I had to download the updated program to the CLX. While I was doing that, we still had the drive cabinet door open (which was in the view of a recording camera).

In the middle of my download to the CLX (ie absolutely NOTHING was running), the drive cabinet exploded. My electrician who was standing ten feet away jumped back from the hot shrapnel that came dancing across the floor. I am so thankful that no one was standing closer.

Our autopsy of the cabinet concluded that we had a phase to phase short across wires in a distribution block at the top of the cabinet. My guess is that there was some loose debris (metal shavings from installation??) that was probably there for a year or more that finally fell into a phase to phase short or maybe there was somehow a dangling thread of a wire that had been there.

What I emphasize to people is that this short was completely random - being experienced and careful would not have mattered that day. It was not caused by the electrician being careless (yes, by some one's previous mistake, but not by the electrician on this day). The electrician had been no where close to the distribution block that day. The short just happened to occur while the door was open and being video'd. Normally this would have been the classic troubleshooting call where the line suddenly stops and when the electrician shows up, he opens the cabinet, sees the black charring, and says "yep, I see the problem".
 
Now you understand
I have a policy whenever I power up a vfd or any drive I always have the panel doors closed and latched. It only need to happen once.
I have a client that had a mercury wetted contactor blow the inside of the panel door is now a nice bright silver color, it will never rust and paint will not hole. every time I pen that panel it reminds me to always close the door

thank the starts nobody got hurt I your plant
 
We had several power failures today, the power was off and on a couple times by the time we got around to all the equipment and got the mains disconnected.


I was looking at the outage map, I don't think I've ever seen so many outages in Halifax.



Now you understand
I have a policy whenever I power up a vfd or any drive I always have the panel doors closed and latched. It only need to happen once.
I have a client that had a mercury wetted contactor blow the inside of the panel door is now a nice bright silver color, it will never rust and paint will not hole. every time I pen that panel it reminds me to always close the door

thank the starts nobody got hurt I your plant


The field guys I normally work with are very strict about closing the panel whenever energizing a disconnect, and I'll never fault them for it.
 
On top of that, it was impressed upon me by the senior guys when I was a newbie to always stand to one side with your face turned away and use your non-dominant hand to throw the disconnect. I still do.

Maybe a bit of overkill but better safe than sorry, right?
 
Glad that you werent seriously hurt.

Have been in a similar situation. Razed all my facial hair off in a microsecond.
Now I dont turn my face away, but I wear glasses, and I shut one eye whenever I feel "this could be dangerous".
 
When I started out in the olden days it was impressed on me one hand for you and one hand for the company, keep one hand in you pocket. But that was back before OSHA and you had to be the safety engineer. I still get a lot of flack when I close the doors when I am on a job with other contractors. but after you have seen as many things blow up as I have you don't worry what other think my safety is in my hands.
I once had a manhole cover blow 20 ft in the air about 30 sec after I put the cover back on after an inspection. it makes one wonder if you picked the wrong trade.
 
After 35 years I still feel tense and expect something to happen when I turn on the power.

The only time something did happen was when I turned on the switchgear to a new (300 Amp) press and a junction box on the conduit run in the ceiling blew a hole in the cover and shot sparks across the building. Turns out the contracted electrician had a habit of not using a wood strut to hold the wires back - he used Unistrut regularly, and it cut through the insulation while the press was being assembled.

Still and eye-opener.
 
Glad your OK... do you guys have Flash PPE laws/standards up there? not that we use them down here but we have one (NFPA 70E) but its good to have something

The only time I get nervous is when you have the loading type switchgear and after you pump the jack a dozen times.... then you hit the button ((SLAM!!)) I had them bounce back and had to reload it all over, I also had a really old air compressor one time, the voltage I think was 2160? I know it was over 2k and you would get a blue light show on the floor every time you started it, each piston was larger than me.
 
Now I dont turn my face away, but I wear glasses, and I shut one eye whenever I feel "this could be dangerous".

Same here... plus a hand in the groin area. Just in case.

This always reminds me of the rampant stupidity in a former workplace where people were to purposely not wear PPE to see who and how long it took before people got stopped.
Needless to say, that was one hell of a pencil whipping exercise from most people.
 
I'm happy to hear you were ok.. This used to happen quite often almost every power bump not the off and back on but the off on off back on rather quickly scenario. We have installed line reactors on every drive and since have not replaced one drive. There was no planning back in the day so things jut got thrown together.. but I will say that they do work.. Regards..
 
We do have safety standards here. Again, like many of us, it may or may not be followed to the letter all the time.

I did have safety glasses on when this happened. But that is all. I really wasn't doing "electrical" work at the time, I was simply opening up the cabinet to reset the breaker. There are 60 drives in this cabinet all with individual over current protection.

Worst thing is, most the people reaching into these cabinets have no idea of the danger so a lot of times PPE isn't even worn. I do realize the danger and I did have (some) PPE and the "Pre-Breaker energize squint on".
We do send everybody to Arc Flash training annually to try and scare safety into them, but at the end of the day, its above my head who management says can work in the panels.

I often preach to them and say, electrician on every shift, they say not possible. Mechanics should have "basic knowledge" and are expected to do some electrical troubleshooting. But every time I get a call from one of them that are arms deep in a panel I say, just put down the meter and step back, Ill be there when I can.

Even recently here, electrical has been removed from the millwright program since Industrial Electrician is becoming a compulsory trade here. Until now, any man and his dog could work at this stuff in an industrial setting.

Its a big can of worms here being as we have had postings out for electricians for over a year now with no applicants other than 1st year apprentice so staffing each shift would be a problem. Especially when I have to tell any interviewee that its a nights / weekend position they are applying for.
 
Reminds me of a story down a slightly different vein. A facility I was working with had their incoming power spike up from 480 to around 700V. Got a call the next day from the power company saying "oops our bad, but we won't pay for any damages". Thankfully it was overnight when MOST things were powered down/disconnected. They spent the next two weeks replacing things as they found devices that had failed/been damaged.

Specifically I remember helping them with a braking resistor that was covered and surrounded with a giant scorch mark and then they were surprised it wasn't working as they expected....
 

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