Medium voltage Metering 3

[mastlog]

Good day guys,
I would like to know how to setup energy meters for Medium voltage lines. I searched on google but couldn't find any meter where i can feed medium voltage directly. Can some one help me out how to accomplish this task.

I have 7KVA line 2500A And i want to install energy meter for this line. In addition the meter should have communication capability so that the data could be displayed remotely on some computer.

Thanks in anticipation,
Best Regards,

 

[magoo2]

Is this a student posting?

 

[mastlog]

No i am not a student. I am a professional control engineer. I would like to get an idea on this topic. Actually i need to prepare proposal for my company how to achieve this task.

 

[Zogzog]

You don't want 7kV going to a digital meter, you will use PT's and CT's as inputs. Tons of options out there and all depends on what you are trying to acomplish. All the major OEMs have meters like this and several specialty manufactures do as well.

 

[waross]

You can probably get your Current transformers and potential transformers supplied in one case. You may want 7.2 kV to 120 Volt potential transformers, (60:1) and 3000 Amp to 5 Amp current transformers (600:1).
You meter multiplier will be 36000. (60 x 600)
You will want revenue class CTs rather than protection class CTs.
Many KWHr meters for use with metering transformers have 5 Amp and 120 Volt inputs as standard. The indicated KWHrs must be multiplied by the multiplier (36000) for the true consumption.
Some of the newer meters have the capability to have the multiplier programed in and will indicate the correct KWHrs.
There are a few exceptions which probably don't apply here.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[amurray]

There are at least two types of metering you could use. Revenue meters are typically calibrated & certificated to be very accurate & used for revenue or billing purposes. Another option is a survey or panelboard meter that also reads energy values. This type of meter is typically less expensive then a revenue class meter. Both types of meters will have several communications options, but typically revenue meters have reading storage schemes so energy values are stored for download on a daily basis. Revenue meters may also have built-in modems and optical communication ports.

So if you are not looking for billing accuracy then you can save on the meter. You can also save some on the CTs by using protection class CTs instead of metering class. There are some vendors that I am familar with for both type of meters

Revenue meters - Transdata, Itron
Panelboard Meter - Bitronics, Electro-Industries, Schneider Electric (Ion Meters)

Andy

 

[mastlog]

Thanks alot guys... the information you have provided is sufficient enough to prepare a proposal for the client. Further i have received some assistance from the CT/PT suppliers.

Thanks again.

 

[ScottyUK]

"You can also save some on the CTs by using protection class CTs instead of metering class."

Thats a good way to destroy your instrument if the CT is installed on a system with a high fault level. Metering CTs are designed to saturate and limit the secondary current during a through fault to protect the instrument; protection CTs are designed to remain accurate ratio at many multiples of their rating and most meters aren't designed to withstand that kind of overload.