Clarification on Tariff Meters

You didn't mention the manufacturer or model of the meter, nor any of its nameplate information. That would be helpful to you. ALso, you should have the instruction manual in your hands.

The 0.08, I suspect, is percent error, not absolute error on 1.00 amps. 8% on a tariff or revenue meter is totally unacceptable error level, but 0.08% would be more like what I might expect to see.

If the meter's display merely truncates the current reading to one digit to the right of the decimal point, then 0.92 amps looks the same as 0.9992 amps -- both would display as 0.9A (as would 0.9000 amps and 0.9999 amps). So you really can't tell from the display what the meter is reading in this case. Is there some other output (serial digital data, or pulsed kWH indication such as KYZ) available?

As for the voltage, you said that input is 110/Rt3 (110/√3 = 63.5085V). That sounds correct to me.

Dear Sir,

Thanks for the quick response. Further details have been furnished in the Trailing post.

Kindly clarify the same.

Regards

Raghavendran.R

Dear sir

0.08 amps error on 1 Amp meter is amounting to 8% error.

Normally Tariff meters for HT consumers will have 2%. error only If you could share the the routine test results, may be I can review and offer comments if any

Best to compare the test results with the type test certificate for same type of instrument to be available with the manufacturer.

You get the meter tested with TNEB/CEIG/independant test Laboratory at Instronic Campus, Tharamani

Dear All,

I beg your pardon for not providing sufficient details related to the tariff meters. The Meter is Elster A1800 Make (Imported from Romania). Model number is A1882. The % of error mentioned by the Manufacturer is 0.08. i.e for 1 A CT input, the relevant OP should have been .9992A. But when we checked yesterday, the meter was showing a truncated value of 0.9 A.

Also the power OP in MW was showing for CT and PT secondary inputs and not for the primary values. ie. Our Full load current is 200 A. The CT ratio selected was 400/1A. The Power OP indicated in display should have been for Primary CT and PT values. Is it the usual way if indication of Tariff power.

The instrument has to be configured for proper display and output.Generally these instruments will display parameters of primary value.

Some times display may not be perfect due to digital display restrictions.

You may take the output in print form and verify.

Gothru the instrument manual for all these instructions carefully.

Dear Sir,

Thanks for the quick response. Further details have been furnished in the Trailing post.

Kindly clarify the same.

Regards

Raghavendran.R

With many of these meters, the readout is set to 'integer' by default. When you find the full users manual, there should be a way to set it to 'floating point'. The meters I use are RS485/MODBUS connection, and take some digging to find the correct registers to modify to obtain the desired functionality.