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KWH readings, line and load side of transformer #213864 08/19/14 01:24 AM
Joined: Aug 2014
Posts: 4
C
captzap Offline OP
New Member
would the KWH readings be the same on the line side of a 480 volt transformer and the 208 load side of the transformer minus the efficiency effects?

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Re: KWH readings, line and load side of transformer [Re: captzap] #213867 08/19/14 09:47 AM
Joined: Apr 2002
Posts: 7,113
HotLine1 Offline
Member
By math, yes.

Welcome to ECN


John
Re: KWH readings, line and load side of transformer [Re: captzap] #213869 08/20/14 12:09 AM
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captzap Offline OP
New Member
Thank you.Installing Emon-Demon system for tenant metering

Re: KWH readings, line and load side of transformer [Re: captzap] #213870 08/20/14 01:53 AM
Joined: Jul 2004
Posts: 9,394
G
gfretwell Offline
Member
The difference should be a fairly accurate measurement of the various losses in the transformer and associated wiring.
Virtually all of the loss is eventually going to end up as heat, as is the case in anything electrical.
When we were calculating HVAC loads in computer rooms the sensible heat always included the total electrical input to the room at 100%. (3412.142 BTU per KWH, usually rounded off to 3400)


Greg Fretwell
Re: KWH readings, line and load side of transformer [Re: captzap] #213871 08/20/14 09:23 AM
Joined: Apr 2002
Posts: 7,113
HotLine1 Offline
Member
Just an FYI, follow the Emon install instructions...


John
Re: KWH readings, line and load side of transformer [Re: captzap] #213874 08/21/14 12:20 AM
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captzap Offline OP
New Member
Yes, it was designed by an engineer who shows 2 sets of ct,s on the load side of transformers. This will work in favor of the tenant. I would correct this but they sent 208v meters, need 480v meters to make it work. The landlord will have to take the heat.

Re: KWH readings, line and load side of transformer [Re: captzap] #213875 08/21/14 01:35 AM
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Posts: 9,394
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gfretwell Offline
Member
If the tenant is actually supposed to pay for what they use, the CTs should be on the load side of the transformer.
The transformer is the landlord's equipment and he needs to recover that money somewhere else in the rent, just like he has to do with parking lot lights and exit signs.


Greg Fretwell
Re: KWH readings, line and load side of transformer [Re: captzap] #213877 08/22/14 12:38 AM
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Posts: 4
C
captzap Offline OP
New Member
Thanks for the input, system is up and running. Now it is time to teach the landlord how to read and bill for KWH & demand

Re: KWH readings, line and load side of transformer [Re: captzap] #213878 08/22/14 01:43 AM
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Posts: 9,394
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gfretwell Offline
Member
I assume this is sub metering (landlord owned meters). He will need to compare the total PoCo bill to what he records for each tenant and consider the difference "house load" and recover that in another manner.
I am not sure where you are but in Florida they have to bill sub metered power at the same rate they pay, including all attached fees. They can't tack on a landlord service fee or increased rate as part of the power bill.
Prior to that law, there was lots of abuse. Places like trailer parks were marking up the power 100%.


Greg Fretwell
Re: KWH readings, line and load side of transformer [Re: captzap] #213880 08/22/14 11:11 AM
Joined: May 2005
Posts: 984
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ghost307 Offline
Member
Be sure that he doesn't make a profit on the resale of electricity. Even if it's an honest mistake you risk being on the wrong side of the law.
Their best bet would be to contact the local Utility to make sure that they're allocating the electric costs properly and within the rules.
Here in ComEd territory...resale isn't allowed no matter how you split up the bill (which is overkill IMHO).


Ghost307

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