How to make proper installation with LOTO for power monitor

[5618]

Hi. I’m looking to replace a basic Shark power monitor with a newer one with communication options, probably PowerMonitor 5000. The existing one is panel mount on the incoming gear which has arc flash potential where no safe PPE exists. I can’t open it while energized.

We have a rare power down day coming up and want to prepare for a new power monitor we don’t have yet. I want to get voltage and CT leads prepared from the unsafe zone to a new enclosure that will house the power monitor as a lower arc flash category enclosure that can be opened while the main gear is energized.

For the voltage leads, I’m pretty sure I can make sure they’re properly fused in the existing enclosure to limit the energy to the new enclosure. I’m wondering if a panel mount disconnect would be the best way to provide a LOTO point before the voltage leads leave the unsafe enclosure.

I am also wondering the best way to deal with the CT leads. I know a shorting block is the way to make the leads to the monitor safe to connect and disconnect. I know they don’t have the energy for a severe arc flash, but I want to make sure it’s proper.

I’m thinking that an intermediate enclosure might be the way to go to hold the shorting block. The CT leads would come out of the gear and land on the block. From there, a continuous piece of wire for each CT would leave the block, go to the meter enclosure, through the meter, and back to the block. We could PPE up, open that intermediate enclosure, short the block, then remove the wires to completely de-energize that part of the monitor enclosure. A lock tab on this enclosure would provide a LOTO point. I kinda want to put a secondary fuse holder or other disconnect means in this enclosure for the voltage leads to share a single LOTO point with the CTs. That seems less proper, but not any worse dealing with the shorting block.

Please give any suggestions, examples, or other insight you might have. Thank you.

 

[5618]

As a follow up, we actually have two incoming feeds. Each one will get a new PowerMonitor 5000. The old one has a Shark meter, the newer Siemens gear has a Siemens meter. I knew what was inside the old gear. I had no idea what was inside the newer gear.

When I last posted, I was looking for a way to LOTO current and voltage to de-energize the new power monitor enclosure. I didn't find any LOTO device to short the CTs, so I didn't bother with LOTO for the voltage.

When power was down and I explored the innards of the gear, I changed my mind about replacing the old meters. The old ones stayed and I'm adding the new ones. I put an enclosure on top of each gear to house the future power monitors.

We got two 1400-PM-ACC kits. They didn't come with a traditional shorting block like the existing ones in the gear. They are a series of Allen Bradley contact spring terminal contact blocks with push in jumpers. I'm not sure if I like that, but that's what we had. I wired the current leads in series with both meters. (well, to the shorting block terminals in the new boxes)

For voltage leads, I brought a set of wires up to fuse holders mounted in the new enclosure. At the gear end of those wires, I replaced the original fuses in the old gear with low peak CC fuses. The newer gear had good fuses.

The Siemens gear has a control transformer to supply 120V for that meter. It appeared to be direct and unfused from the secondary to the meter without a quick and easy way to use that to power my new meter. I think it was 50VA which might not be enough anyway. I'm not revisiting that with the gear energized, even though that meter is reasonably housed to be opened if needed while energized.

If I had more time, I might have done something with that control transformer and done something similar in the old gear to power the new monitors, but the allotted window was ending. I'll have to bring in 120VAC or maybe 24VDC from elsewhere to the new enclosures.

 

[cardosocea]

Last I had one replaced (was actually a current meter for an energy meter), the guys doing the work installed some heavy duty terminal disconnects on purpose to allow the current and voltage leads to be isolated in the enclosure where the meter was installed.