Scale Factor Setup - Dranetz PowerGuide 4400 User Manual

Scale Factor Setup

Scale Factor Setup

What is a scale
factor?
When to use
Non-Dranetz
equipment
Sample
calculation
5-10
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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 4400 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 current probe is connected to a permanently installed CT.
• The current connections are made using a Dranetz 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:
Example of step-up ratio
If a potential transformer has a step-up ratio of 1V:10V, therefore:
www.
Scale Factor = 1000/5 = 200
Scale Factor = 1/10 = 0.1
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