Gossen Metrawatt M817S Mains-analysis device, Mains analyser M817S Hoja De Datos

5-10

Scale Factor Setup

A scale factor is the ratio of the input to output for a particular current transformer (CT) 

or potential transformer (PT). A scale factor is entered in the Energy Platform and then 

multiplied automatically by the measured voltage or current so the unit displays the 

correct values, as referenced to the primary side, rather than the secondary side of the 

PT or CT.

NOTE: If voltage and current connections are made without using any of the above 

named devices, the scale factor should be set to 1.

Scale factors must be entered for the following conditions:

• A Dranetz-BMI current probe is connected to a permanently installed CT.

• The current connections are made using a Dranetz-BMI ISO box.

• The voltage connections are made using a PT.

Refer to the CT name plate or to the manufacturer’s literature to determine the scale 

factor.

The scale factor for a single CT or PT is calculated from its step-up or step-down ratio.

Example of step-down ratio

If a current transformer has a step-down ratio of 1000A:5A, therefore:

Scale Factor = 1000/5 = 200

Example of step-up ratio

If a potential transformer has a step-up ratio of 1V:10V, therefore:

Scale Factor = 1/10 = 0.1