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 Post subject: Substation Kiosk
PostPosted: Wed Apr 17, 2013 6:11 pm 

Joined: Tue Mar 05, 2013 3:06 pm
Posts: 1

I am new to the forum and would like to get some feedback on Kiosk Substations. Here in Australia and I assume all over the world, substation kiosks are key for MV distribution. They are located next to paths, in parks and basically everywhere, especially with underground power networks. Now the chance of an Arc flash event in these substations can occur and I have been looking at ways to either eliminate the risk associated with Arc flash or reduce the risk. I know that there is an Arc flash rating for these substations, being IAC-A or IAC -B or IAC - AB. But this rating is only for the medium voltage side.

Now my question is has anyone had any dealings with these kiosk substations and what did you do. I know you could get the IAC - AB rating and then also install LV MCC arc contained units but that would be huge money. Also do you agree that the MV side is much more likely to arc. The MV side has fuse protection so the Arc level is low, whereas the LV side is quite high. Being cat 4.

Would really appreciate any feedback.

Thanks Bradley

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PostPosted: Sun Apr 21, 2013 4:38 am 
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Joined: Tue Oct 26, 2010 9:08 am
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Location: North Carolina
The MV side is normally LESS likely to arc especially because the maintenance requirements to minimize damage due to tracking/PD which does not occur below about 2000 V and that you have greater separation and (in US installs of similar equipment) thesedays everything is dead front with IEEE 386 connectors, arcing faults are very unlikely. At 400 V or below arcing faults are pretty common failures (about 90% of cable/connection faults are arcing phase to ground as per IEEE Gold book). The major difference is that as the voltage decreases much below 400 V the likelihood that the arc is self sustaining is very small. IEEE 1584 does not take this into account.

There are few choices. You can approach it with PPE. You can go to solidly insulated systems. You can use a breaker on the primary side (or "smart" fuses) and create a virtual breaker arrangement on the secondary side. You can use a hot stick to operate the primary disconnect from a distance. You can build equipment similar to ATEX initiative designs where an arcing fault is harmlessly vented. Or you can test the equipment in a testing lab such as Kinectrics to determine under what if any circumstances an arcing fault can be sustained. Last possible option is adding an arc "terminator" type device that purposely shunts either the bus or resistors temporarily to quench the arc.

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