Arc Flash and Infared Inspection of Switchgear

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Davebones

Senior Member
We are starting to get a push from management to start doing more preventive maintenance . One of things they would like to do is more infared scanning . We have five ( 5 ) services that come into the plant . At the switchgear of each service the incident energy level is at least 94 cal/cm2 or greater . The warning label says ( Dangerous ! Exceeds NFPA 70E PPE Categories ) . How do you get to do infared scans when the incident energy level is so high and no PPE will protect you . Just looking for opinions on how other maintenance shops are dealing with this ...
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
There are windows that can be added to allow you to scan the interior without opening up the gear.

I am not convinced that the typical IR scanning that most places actually do is worthwhile. I think it should be done at times of peak use. Many places actually do it during scheduled shutdowns.
 

hurk27

Senior Member
well you got one of those problems that really doesn't have an answer, since the only legal way to open that switch board is to have it shut down, but then this kind of defeats the IR scanning because you are looking for hot spots that will only show up when there is current loading, sure you could shut down and quickly open the panel then snap some images of the connections but if you have a connection that cools it's self then you could miss an important spot and make your PM worthless. or power up the panel leaving the door open but that too would be a big OSHA violation if something were to happen, so I guess that I am of no help in this matter, kind of a like being caught between a rock and a hard place, please the boss and take a chance with getting hurt or killed, make the boss aware of the issue and see if they can have a window installed when the line is down, nether is a good choice the the latter is the one I would pursue?
 

Sahib

Senior Member
Location
India
If you use ultra sound detection with IR, effective use of IR after equipment shutdown is ppssible.
 
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petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
well you got one of those problems that really doesn't have an answer, since the only legal way to open that switch board is to have it shut down, but then this kind of defeats the IR scanning because you are looking for hot spots that will only show up when there is current loading, sure you could shut down and quickly open the panel then snap some images of the connections but if you have a connection that cools it's self then you could miss an important spot and make your PM worthless. or power up the panel leaving the door open but that too would be a big OSHA violation if something were to happen, so I guess that I am of no help in this matter, kind of a like being caught between a rock and a hard place, please the boss and take a chance with getting hurt or killed, make the boss aware of the issue and see if they can have a window installed when the line is down, nether is a good choice the the latter is the one I would pursue?

there is no requirement that the door be closed just because of the IE available. As long as everyone stays outside of the arc blast zone there is no reason the door can't be open for IR inspection.
 

Davebones

Senior Member
At 94 cal/cm2 the Flash Protection Boundary is 257 inches . Roughly 21.5 feet . Is that really feasible to even consider trying to do Infared Scan at this distance ?
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
At 94 cal/cm2 the Flash Protection Boundary is 257 inches . Roughly 21.5 feet . Is that really feasible to even consider trying to do Infared Scan at this distance ?

Have you performed a risk assessment as required by 70E-2015, in articles 130.4 and 130.5(1) as well as other locations?

The Arc Flash Protection Boundary is the point where the incident energy is only 1.2 cal/cm^2, how close can you be and still be in 40 cal/cm^2 PPE?
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
But someone has to be close enough to unbolt/open the door or cover.

they can turn the power off to open the door and then get the heck out of the way and turn it back on.

I am not saying it is the most convenient thing to do, but that is one way.

By being clever you might find other ways to do it.

You can also get an upstream OCPD that has a mode where it operates a lot faster then normal while that mode is selected that reduces the available IE while in that mode. You turn the key to faster operation, open the door, and turn the key back to normal.

There is no rocket science involved here. It is just about money mostly.
 

wbdvt

Senior Member
Location
Rutland, VT, USA
Occupation
Electrical Engineer, PE
At 94 cal/cm2 the Flash Protection Boundary is 257 inches . Roughly 21.5 feet . Is that really feasible to even consider trying to do Infared Scan at this distance ?

AR PPE is only required when the task being performed has the risk of an arc flash associated with it. Therefore, removing a cover to expose the energized equipment is a task which requires AR PPE.

Once the cover is off, the risk of creating an arc flash is removed as long as there is no work being done near the energized parts. What you have now is a different hazard - shock. Therefore one needs to adhere to the limited and restricted approach boundaries. If the infrared tech is an unqualified electrical worker, he could still perform the IR at the limited approach distance.

Since you have had a study done, I guess there was no way to reduce the incident energy so I am guessing that the protective device is on the primary side of a transformer and this equipment is connected directly to the transformer low side. The best option is to have IR viewports installed at the next equipment shutdown.
 

Sahib

Senior Member
Location
India
they can turn the power off to open the door and then get out of the way and turn it back on.
You can also get an upstream OCPD that has a mode where it operates a lot faster then normal while that mode is selected that reduces the available IE while in that mode. You turn the key to faster operation, open the door, and turn the key back to normal.
In doing so, approach distance as pointed out above to avoid any arc flash due to any fault after the cover is removed is to be respected.
At 94 cal/cm2 the Flash Protection Boundary is 257 inches . Roughly 21.5 feet . Is that really feasible to even consider trying to do Infared Scan at this distance ?
Consult the IR scanner manufacturer.
 

pfalcon

Senior Member
Location
Indiana
How about:
Turn it off.
Mount and focus the camera for the picture.
Turn it on.
REMOTE trigger the camera.
Turn it off.
Collect the camera.

Who says someone has to be holding the camera?
 

zog

Senior Member
Location
Charlotte, NC
Just install IR windows and you never have to worry about it again, or better yet install IR sensors in the gear for continous monitoring/alarms. We have installed many of both of these systems with great success.
 

mayanees

Senior Member
Location
Westminster, MD
Occupation
Electrical Engineer and Master Electrician
clever AND safe

clever AND safe

.. to Bob's point, I will reduce my PPE requirements by increasing the working distance. IE is calculated from a given point source in the gear, but the arc flash boundary is typically based on the front of the gear. So a typical 480V piece of gear with an IE posted on the AF label can be accessed with a lessened PPE if the point source is not at the front of the panel.
If I double the working distance, the IE is reduced to approximately 1/3 of the posted IE level.
I'll typically do data collection in PPE 2, and will keep far away enough from an IE point source to remain protected by the 8 calorie suit. A typical example is that I can get within 48 inches of a 40 calorie source in PPE 2 and still limit potential burns to 2nd degree.
 

meternerd

Senior Member
Location
Athol, ID
Occupation
retired water & electric utility electrician, meter/relay tech
Our IR cameras have a video out connection. These can be sent to a recording device or to a remote monitor. If you set up the camera, clear the area, open the covers and fire it all up, could you not then monitor the images from a safe distance? Just a thought. Our cameras are FLIR, so maybe they're unique.
 

rt66electric

Senior Member
Location
Oklahoma
IR cameras do not read through glass.??

IR cameras do not read through glass.??

Just install IR windows and you never have to worry about it again, or better yet install IR sensors in the gear for continous monitoring/alarms. We have installed many of both of these systems with great success.

I have played with a IR camera ... It does not "see through" or "read through" glass.
It either reads the temperature of the glass , or senses the heat reflected image , like a mirror. similar to a selfie in a mirror.

is there a special window??
 
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