Some help with an industrial Elec drawing from 1998

Calahonda52

Need some help with the attached.
Need to understand the diagram:)
What does MDM mean in this context.
Are there two ESB supplies to each of the 800 Amp ACBs?
whats the Mechanical interlock about/for
Are the ESB CT's for their meter?
Thanks, as always.

ps
what are Motor Control Centre (MCC) Control panels for: I have a 37 page pdf ( entitled MCC 1 Control Panel wiring diagram ) for the AHUs

Luckysasha

MDM is Max Demand Meter
I'd say the two supplies are possibly one from ESB rural supply and the other one is from a standby generator or similar non ESB source. The interlocking is to prevent back feeding on to the ESB network.
The ESB CT's are for metering purposes. Anything over 100A per phase is metered via CT's.

Calahonda52

Luckysasha wrote: »

MDM is Max Demand Meter
I'd say the two supplies are possibly one from ESB rural supply and the other one is from a standby generator or similar non ESB source. The interlocking is to prevent back feeding on to the ESB network.
The ESB CT's are for metering purposes. Anything over 100A per phase is metered via CT's.

Thanks.
Spot on re the standby generator:)
What purpose does the MDM serve as opposed to the normal meter?
Why have one on the generator circuit?

Luckysasha

As far as I can remember from my time in metering, the MDM meter was the customers meter. The ESB meter is not show in the drawing. It's just represented by the CT's. Max demand meters where also referred to as landlord meters

Stoner

There would not be an ESB customers meter on the generator though would there ?The change over panel would offer either or power as suggested but there would be no esb meter if one supply is from a genset the esb can't charge for your generation. I agree mdm sounds like maximum demand, but as you know that is still a term used today.

It might be some sort of multi digital meter.
Just a thought

Also if there were two esb supplies from different sources they would be metered and interlocked. But I dont think that's the topology for that in the pdf.

Calahonda52

Thank guys, going on site this morning so will hopefully know more.:)

Luckysasha

Stoner wrote: »

There would not be an ESB customers meter on the generator though would there ?The change over panel would offer either or power as suggested but there would be no esb meter if one supply is from a genset the esb can't charge for your generation. I agree mdm sounds like maximum demand, but as you know that is still a term used today.

It might be some sort of multi digital meter.
Just a thought

Also if there were two esb supplies from different sources they would be metered and interlocked. But I dont think that's the topology for that in the pdf.

No the Max demand meters are for the customers reference only. They would be located in the customers switch room. The CT's refer to the ESB meter which would be separate from the customers meters. They are usually located in the same switch room but I have seen them mounted in the ESB sub

Dardania

Calahonda52 wrote: »

ps
what are Motor Control Centre (MCC) Control panels for: I have a 37 page pdf ( entitled MCC 1 Control Panel wiring diagram ) for the AHUs

It should be the power & controls to the mechanical plant (as you say air handlers, pumps, boilers etc.)

I have drawn countless of those schematics - it's good to hear you're going on site, as these schematics are usually not updated following construction, so be ware of inaccuracies. Or if they are updated, you will find the revised drawings in a document holder in front of the panels

Calahonda52

Thanks again to all of you:
its a Carlo Gavazzi EM 26 - 96 Energy Analyser thats on the ESB feed and a Electrex Multi Data Meter, so MDM on the Gen ACB

Both are not working: they then have Socomec Countis E 50's on a newer distribution board installation.

Its a very high spec setup and everything is maintained/recorded so the pdfs were as installed/changed, updated in May 2014