How to calculate the slowness and fastness of energy meter if we have different kw load for example (0.746 kw and meter rev constant 400 and we calculate the 2 rev in 30 sec) and explain the formula ?

 Meter rev constant means rev/ kwh.

 Then one rotation = 60×60/400 or 9kws.

 2 rotations = 18kws.

 Time taken is 30s.

 Then the av load is 18/ 30 or 0.6 kw.

 To calculate whether this Energy Meter is slow or fast using this formula.
 Slowness/Fastness=Tc−To/To X 100