Energy meter multiplication factor

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siva

Member
Hi
I am working with US Navy,Middle east.Here our contractor fixed one energy meter made in Saudi arabia.This is a 3 phase 50 hz meter working with CT.The ratio of Current transformer is 400 to 5.It is not mentioned any multiplication factor.But on the front side of the meter there is a blank room to write the multiplication factor.Can we find this factor from the CT ratio.

Thanks in advance
Siva
 
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newt

Senior Member
Re: Energy meter multiplication factor

First you will have to determine if the meter itself has a constant of 1. Some meters will have aconstant of 1.5 or 2. most electronic meters have a constant of 1.kh x reg. ratio x first gear \ 10000 = meter constant. Then you can multiply any ct or pt ratios to the meter constant to get the billing constant, I hope this helps.
 
S

siva

Member
Re: Energy meter multiplication factor

Hi
Thanks Newt.But in Meter's data sheet, it is mentioned that Meter constant(r./kWh)= 2400.What it means? I have to multiply CT ratio with 2.4..?
Please advise..

Thanks

Siva
 
N

newt

Senior Member
Re: Energy meter multiplication factor

Is this meter electronic no moving gears if it is electronic I believe it would be a constant of one.I think your billing constant should your ct ratio.The manufactor of the meter should be able to tell you the meter constant.Dont forget to include pt ratio if you have any.What form is this meter and manufactor.Do you have any other nameplate data.
 
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newt

Senior Member
Re: Energy meter multiplication factor

If the meters kh is 2.4 then the meter should have a multiplier of 2.So your billing constant should be 2 x ct ratio = 160
 
S

siva

Member
Re: Energy meter multiplication factor

Hi Newt...
I still confused.What is kh? Is it equaled to kwh?Or is it a constant?The data sheet shows these details...

Made - MEMF (Saudi Arabia)
Model - T 31Ctp2
Rated secondary current of CT (A) - 5 Amps
Torque at basic load (x10-4Nm) - 24.3 at 5 Amps
Rated number of revolutions - 600
at basic load (r.p.m.)
Meter constant ( r./kWh) - 1200 (2400 was by mistake)

Thanks for your patience

Siva
 
N

newt

Senior Member
Re: Energy meter multiplication factor

Kh is watts per revolution of disk.First gear is the number of teeth on the gear that attaches disk to shaft usually 50 or 100.Register ratio should be on the fase of the meter,On elec/mechanical meter.A total electronic meter will have no mechanical parts,the ones that i deal with have a constant of one.I can not safely tell you the meter multiplier with the listed info.Sorry (I can look in my meter handbook 4/27 and see if i have any other info)
 
R

rattus

Senior Member
Re: Energy meter multiplication factor

Newt, shouln't we say that the meter constant indicates watthours/revolution instead of watts/revolution?
 
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eutaw42

Member
Re: Energy meter multiplication factor

Have looked at electric meter readings for 30 years-- If no CT was used then the difference in the readings gave the kwh used -- demand kw was as indicated on the meter (reset at each reading). If CT metering, usually had 200/5 cts - 40 meter constant, 400/5 cts - 80 meter constant. This constant was mutiplied times both the meter kw reading and the difference in kwh readings for the period of use. This is true for digital or analog meters. Seems like you have an analog meter and are discussing the factors involving the meter's disk turning rate. This is not a factor in the meter constant applied for CT metering. We manually wrote in the constant (40 for 200/5 cts) on the meter face and entered this into the billing data.
 
N

newt

Senior Member
Re: Energy meter multiplication factor

We have many meters that have a constant of 1.5 or 2 depending on the mechanical gears of the meter.That is why it is important to know the kh, gear ratio,and first gear.That is where you need to start it may not be just the ct ratios.Most ge meters have a constant other than one.
 
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