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After selecting a data scalar, the formula for calculating the actual value is:
register value X scalar value = actual value
Or, another way to state this formula is:
actual value/scalar value = register value
Selecting a Scalar
The following table is an example when selecting a data scalar for 3-phase loads based on the CT size or
maximum current. These are the minimum recommended scalar settings.
Examples Using a Data Scalar
The following examples use kW throughout.
For example 1, the following data is used:
Volts x amps = watts
Watts x 3 = system watts
Check the register's value using the data scalar 2 value of .01:
System kW / scalar value = register value
Since 14,400 is less than 65,535, using data scalar 2 is a good choice for this example.
For example 2, the following data is used:
480 volts x 1000 amps = 480,000 watts
480,000 watts x 3 = 1,440,000 watts (1,440kW)
Check the register's value using the data scalar 1 value of .001:
1,440kW/.001 = 1,440,000
Since 1,440,000 is greater than 65,535, using data scalar 1 returns an incorrect result. Data scalar 1 is
not an appropriate choice.
Reviewing this example using the data scalar 3 value of .1 provides the following result:
1,440kW/.1 = 14,400
Since 14,400 is less than 65,535, using data scalar 3 is a good choice for this example.
CT Size or
Max. Current
230 volts
50
Scalar 1
100
Scalar 2
200
Scalar 2
400
Scalar 2
600
Scalar 2
1000
Scalar 3
3000
Scalar 3
Table IV-2: Data Scalar Selection
26
3-phase Loads
460 volts
Scalar 2
Scalar 2
Scalar 2
Scalar 2
Scalar 3
Scalar 3
Scalar 3
480 volts x 100 amps = 48,000 watts
48,000 watts x 3 = 144,000 watts (144kW)
144kW/.01 = 14,400
NOTE: The register
value must be less
than 65,535.
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