Re: can unbalanced 3 phase load make meter run faster?

[Me]

NO!!!


There is 3 phase wire coming into the computer building from the
electrical post outside. Do you think it is important to balance
the load in the 3 phase output of the panel. What is the worse effect
if the load is not balanced. Can that cause the 3 phase electrical
meter to run faster than normal??

K

 

[Ben Miller]

NO!!!

Not always true. If a meter is properly configured using three elements for
a 4-wire system, or two elements for a 3-wire system, then it will register
correctly regardless of balance.

However, utilities sometimes install three-phase meters that use fewer
elements in non-standard arrangements, and the accuracy is based on
assumptions regarding voltage and/or current balance. As an extreme example,
you can meter a single three-phase motor load with one element and then,
either through a multiplier of three or an appropriate register ratio,
obtain three-phase kWh. This will work as long as volts & amps are balanced.
If you add a single-phase load to the phase that is metered, it will
register three times the actual additional load. Of course, it will not
register at all if the load is added to one of the unmetered lines.

Since his system is for a building that is always going to have single-phase
loads, it was most likely metered correctly, but it could have a meter that
would be affected by balance.

Ben Miller

 

[Charles Perry]

Note I installed the 3 phase electric meter myself after connecting
3 big wires to the power lines. In other words, the building doesn't
have existing meter. I let my men tap directly from a high powered
transmission line. I didn't design the load in each phase, I just put
whatever I can put in. That's why I'm concerned if the meter would
run faster if the load is not balanced (which isn't).

kyle

You need to explain this a little more clearly. Why would the building have
no meter? Is it part of complex of buildings with a single utility revenue
meter? You tapped a transmission line? What voltage? Wye or delta? What
Form is the meter (it is stamped on the face plate)?

You see, knowing that the utility did not install this meter it is all
together possible that the meter may not be the correct form for the service
voltage and type. If that is the case then unbalance could affect it
greatly.

Charles Perry P.E.

 

[Ben Miller]

Note I installed the 3 phase electric meter myself after connecting
3 big wires to the power lines. In other words, the building doesn't
have existing meter. I let my men tap directly from a high powered
transmission line. I didn't design the load in each phase, I just put
whatever I can put in. That's why I'm concerned if the meter would
run faster if the load is not balanced (which isn't).

kyle

This scares the hell out of me!

Ben Miller

 

[Charles Perry]

This scares the hell out of me!

Ben Miller

At the risk of offending Phil, it scares me also.

Charles Perry P.E.

 

[Ben Miller]

I got scared too that day when the electrician I hired tried to connect
the 3 wires to the transmission post. He accidently touched the 2 live
wires together and there was this huge loud spark nearly making him fall
15 meters down. Glad he was able to balance himself or may have to answer
his medical expense. But it's ok now since the wires were
successfully installed. Btw. not sure whether the meter is delta wye
or others since I just bought it on recommendation by people.

So let me see if I have this straight so far...
You sent an unqualified electrician to make a connection onto the utility
lines, which the landlord said would work, with a wire size that was a guess
based on an unknown load, with an unknown meter configuration that some
people told you to buy. He shorted the lines and is lucky to be alive, but
things are OK now since everything is working.

You didn't mention anything about permits, inspections or meter installation
by the utility. I hesitate to ask, but do we assume that none of that took
place?

Ben miller

 

[Charles Perry]

Because the building load is already used up so the landlord told
me to connect my own wires to the posts since the existing ones are
in full capacity. The landlord also said the transmission lines can
handle it. So I hire some electricians to connect it to the post using
thick 4/0 wires. My concern is the 3 phrase electric meter since I
didn't design all loads to be balanced.

kyle

Where are you? Making such a connection is illegal in most places that I
know of. I guarantee you did not connect to transmission lines since you
and your electrician are alive. Transmission voltages start at around 35kV
(this is distribution for some, subtransmission for others).

If you do not know what you connected to (wye or delta) then you can't
possibly know if you have the correct meter (it matters...alot), and then we
cannot answer your unbalance question.

Charles Perry P.E.

 

[Charles Perry]

I already made downpayments to the place but initially told them I'd
just put up 30 computers. When they learned it's double. We were
supposed to apply at the electric company, but it would take weeks
or months and we can't afford delays. So since we would tap legally
with meter. We have to do it deep in the night to prevent policemen
from seeing us and arresting us as they usually arrest people tampering
with power lines. But we are not stealing electricity but just tapping
it with legal meters approved. And we can't afford long delays from
permit application. To be sure the wire won't overheat. We use very
thick ones called 4/0. Now the balancing is what I'm concerned as well
as the internal wiring where I used a bit thinner ones (which I'm
thinking whether to replace with thicker ones and save electricity).

Kyle

Sorry, I can no longer help. You have obviously connected illegally. You
have no idea whether you have the correct meter for your service so there is
no way we can answer your unbalance questions.

What country are you in?

Charles Perry P.E.

 

[©¿©¬]

I understood he is connected at the input panel of the building entrance,
downstream from the utility meter. His power meter is used only for the
landlord to charge him his electrical consumption.

1. I am sure this installation is undersized & unsafe.
2. Unbalanced three phase load is not dangerous in itself if properly
protectected upstream by the right size three phase breaker. However, this
very breaker is going to trip when the first phase reaches the limit,
thereby cutting off power to all your load.
3. As for the meter running faster i.e. indicating more electrical
consumption, I doubt any one of us can answer without specifics you haven't
provided, and apparently you're not qualified enough in this domain to
describe.
4. Stick to your computer business and hire a qualified electrical
contractor.
5. Have you heard of Business Impact Analysis, it only means what will it
cost you if the cheap ad hoc electrical job fails ?

My humble guess is many times more the cost of a proper electrical
installation.

Tommy