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I need information on the major difference between an WHOLE CURRENT energy meter and a KWH energy meter, if there is.Any link or resource information would be of great help.

Thanks

Paul A.
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"Whole Current Meter" is an industry jargon term for a (probably) single phase meter used to measure AC mains current in which the whole current to be measured flows directly through the meter - as opposed to eg current transformer type measuring systems where the current is converted to an indirect variable which is measured by a meter which is not directly measuring the actual current.

This reference "Automated Meter Reading Key Information for Members" says on page 6

  • Additionally, electricity meters are one of two types, either whole current or current transformer. A whole current meter is where the electricity supply passes through the meter itself, while a current transformer (in simple terms an electro-magnetic ring around the wire) or CT meter is where current transformers are used. Whole current meters are used in single phase supplies whereas CT meters are used for three phase supplies.

This document "Validating non-utility meters for NABERS rating" notes some important practical consequences and areas of application. Viz -

  • Electricity meters ... are either ‘whole current’ (direct connect), where all the electricity flows through the meter, or CT meters, where the electricity flows through a Current Transformer which reduces the electricity to flow through the meter by a defined ratio.

    A whole current meter is typically used for loads up to 100 amps and CT meters for larger loads. An exception to this is where small panel mounted electronic meters are installed that use CTs regardless of the current flow

  • All non-utility electricity meters with CTs must be validated (and corrected if necessary) by a licensed electrician or electrical engineer to ensure that the CT ratio (meter multiplication factor) and wiring is correctly configured.

But

  • Whole current meters without CTs that are manually read, with no interpretation by a Remote Meter Reading System, are not subject to these rules

Note: A whole current meter measure current (Amps) and not energy (KwH) but a kWh meter may conceivably use either whole current or current transformer measurement methods.

Russell McMahon
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  • Thanks @Russell. It was very helpful! But is it possible to have both 3phase and 1phase whole current meter. Because the links specifically stated for single phase installations. Also, will there be a need for a particular Metering chip specifically for measuring whole current, since the entire current will have to flow the meter. Also how will you describe the meter that used the shunt to measure current instead of the CT. Could that be called the whole current meter as well? Thanks so much! – Paul A. Sep 19 '11 at 16:05
  • http://www.securetogether.com/Sprint.aspx – Paul A. Sep 19 '11 at 16:55
  • This seems more a matter of terminology and regulatory requirements - so you will need to interpret the terminology in your local situation. Technically it is easy to make a 3 phase "whole current" meter. My interpretation only is that a shunt based meter would be whole current if you used "ohmic connections" to measure the drop across the shunt but probably not if you used eg a Hall sensor to measure current in the shunt. Their reasoning seems to be that a "transducer" requires calibration, which must be checked. A Hall sensor is far more likely to be out of calibration compared to a CT. – Russell McMahon Sep 20 '11 at 03:13
  • @Paul A - From Paul's link - Choose "Download Brochure" at bottom of page Standards IS13379, IEC 62052-11, IEC 62053-21, DLMS Indian Companion Standard may be of relevance. – Russell McMahon Sep 20 '11 at 03:19