How much to R&R an E-mon D-mon?

[LarryFine]

Hey, guys, I'd like opinions on removing and replacing an inoperative 8-year old E-mon D-mon, the meter and the CT's. It's a 2500a 480Y/277v service in a store in a mall. The meter is mounted on the face of the switchgear within 2 ft of the busbars the CT's are on.

The existing unit, along with a second meter, registers power use, but neither accumulate watt-hours. I think the second meter (which mounts to a base like, and looks somewhat like, a POCO meter) I wonder if two sets of CT's might interact this way, but I doubt it.

I'll have to kill the main power, bring in a couple of lights on an inverter, and working after hours. I figure on this taking not more than an hour, will plan on two hours, and will ask them to allow me three hours. I'll have to remove both existing meters and sets of CT's

Before I submit my proposal, can anyone think of any reason two separate sub-meters would share the same symptoms, not registering KwH's? The other meter has an LCD readout with little bars across the bottom that represent a moving disc, and they move.

I am recommending replacement, rather than troubleshooting, the existing unit, which is past the 5-year warranty. I talked with tech support at E-mon, and the guy basically agrees with me. Any and all thoughts are welcome. Thanx!

 

[iwire]

Be careful when ordering that you get the right E-Mon Demon meter, may sound obvious but I have been sent the wrong ones more then onces (others placed the order)

Get split CTs so you don't have to pull the conductors off the terminals.

You probably already know this but keep the CTs loaded before energizing the service.

 

[LarryFine]

Be careful when ordering that you get the right E-Mon Demon meter, may sound obvious but I have been sent the wrong ones more then onces (others placed the order)

Yep. I need the 4803200D.

Get split CTs so you don't have to pull the conductors off the terminals.

Absolutely, like the last one I did.

You probably already know this but keep the CTs loaded before energizing the service.

Oh, yes! Just like CT's. :wink:

 

[emahler]

You probably already know this but keep the CTs loaded before energizing the service.

can you explain?

 

[charlietuna]

You should have three wires providing each meter phase voltage and one nuetral. Then a pair of wires from each CT. Depending on the age, you should be able to troubleshoot each meter from the meter. Are you sure they EVER worked ? If the polarity on the C.T. is wrong or if the phase voltage tap(A-B-C) doesn't match "IT"S" C.T. phase it will not record. Don't forget the C.T. have to have the line-load in the correct direction. I would contact E-MON again and let them walk you thru troubleshooting the existing units--they are usually very good. Both meters acting the same sounds like it might be "operator error" and this equipment is fairly reliable. This might be the first time they are attempting to monitor power useage?

If your going to replace the existing, make sure you have everything pre-fabbed--the C.T. with extended wire if necessary and phase tape to match them to their phase voltage. This is time consuming, especially as tight the termination space is. Three hours should do it--IF YOUR PREPARED.

 

[LarryFine]

can you explain?

A CT will act as a step-up tramsformer if the secondary is left open when the primary is carrying current. The insulation on the wire in the coil can be breached by the high voltage developed.

 

[emahler]

A CT will act as a step-up tramsformer if the secondary is left open when the primary is carrying current. The insulation on the wire in the coil can be breached by the high voltage developed.

ok....never heard the phrase bob used...not i'm hip:grin:

 

[LarryFine]

Are you sure they EVER worked ?

Hard to say. The guy who initiated the service call started in Feb, and nobody seems to know how long they've been out of commission.

This might be the first time they are attempting to monitor power useage?

They've been using them to recover power costs from each tenant. I installed one in the same mall several years ago.

Three hours should do it--IF YOUR PREPARED.

Thanx for the advice. As stated, I have installed them before, and I know what to look for.

Added: The last one I did took me about an hour.