With multipliers you need to be certain that the meter reads the primary values or the secondary values of power consumed.
For example 200 / 5 Amp CT's give a current multiplier of 40.
In case of primary values, the meter is programmed to show true readings as the CT multiplier is already programmed in the meter. Usually that should be visible on the meter display as the register button is pushed.
With the older mechanical meters gears can be changed to make the register read direct values. ( multiplier is X 1 )
In case of secondary values ( We call that in NZ a blank 5 meter ) the multiplier has to be added to the readings.
It is good practice to affix a multiplier label to the meter. In the 200/5 A case it is X 40.
In this case it is easy for the meter installer not to have to program the meter as a blank 5 meter can be fitted on any CT installation as long as the correct multiplier is affixed to the meter.
A CT inspection report should be kept on file which records the CT settings and a current test report as primary and secondary currents are measured to prove that the CT multiplier is correct.
