Inflated electricity Bill,....Why? ----- Part-II

REASON FOR FAST RUNNING OF ELECTRIC METERS  - Part-II

         - Why bills of electric consumption suddenly increased when          electromechanical meters replaced with electronic meters?

SUDHIR KUMAR SRIVASTAV

AGM-RAPDRP

NTPC LIMITED, NEW DELHI

Sudhirksri1@gmail.com

This is in continuation of my previous blog Inflated Electricity Bill…Why?’

There is one more reason for inflated electricity bill to single phase consumers as described below:.

In case of normal circuit as shown above:

• Current across the meter = I
• Voltage across the meter = V
• Power flow through meter W = V I CosØ 
• Energy recorded by meter P = W t

As V is actual voltage, I is actual current & CosØ is actual power factor, the energy recorded by meter shall be actual.

But in case the neutral of the meter is disconnected from the pole (supply side), and neutral side of the load is earthed as shown above, following will be the condition:

·         Phase will be available to load, through energy meter. Current will flow through the energy meter and power will be available at load, as second point of load is earthed.

·         In case of electromechanical meters, current through meter will be I. But voltage across meter shall be zero, resulting NIL record on energy consumption.

·         But in case of electronic meter, a feature is made available in the meter that, if current is flowing through current coil & there is no voltage across voltage coil, the calculation of power shall be based on normative value of single phase voltage i.e. 250 Volt & based on normative value of power factor i.e.  1.

·         In such a situation, if actual voltage of supply is 220 volt & actual power factor is 0.95, the actual energy flow shall be = 220 x I x 0.95 x t (Here 220 is voltage, I is current, 0.95 is PF & t is time)

·         But due to broken neutral, normative value of voltage & PF shall be 250 V & 1 and recorded energy through energy meter shall be = 250 x I x 1 x t. (Here 250 is normative voltage, I is actual current, 1 is normative power factor & t is time).

·         So % increase of recorded power w.r.t. actual consumed power shall be =

                         (250 x I x 1 x t  -   220 x I x 0.95 x t)*100/(220 x I x 0.95 x t)  = 19.6%

So we can conclude that, if actual voltage is 220 V, actual power factor is 0.95, but neutral circuit of meter is broken and load is connected between phase & earth, the energy recorded by electronic energy meter may be 19.6% more than actual energy consumption.

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