Prepping for Installation
33
Building Technologies 125-202
06/06/2017
● If the data scalar selected is too high, the significant digits following the decimal
point are removed.
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
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:
Table 8: Data Scalar Selection.
CT Size or Maximum Current 3-Phase Loads
230 Volts 460 Volts
5 Scalar 1 Scalar 2
20 Scalar 1 Scalar 2
50 Scalar 1 Scalar 2
100 Scalar 2 Scalar 2
200 Scalar 2 Scalar 2
400 Scalar 2 Scalar 2
600 Scalar 2 Scalar 3
1000 Scalar 3 Scalar 3
4000 Scalar 3 Scalar 3
Examples Using a Data Scalar
The following examples use kW throughout.
For example 1, the following data is used:
Volts x amps = watts 480 volts x 100 amps = 48,000 watts
Watts x 3 = system watts 48,000 watts x 3 = 144,000 watts (144kW)
Check the register’s value using the data scalar 2 value of .01:
System kW/scalar value = register value 144kW/.01 = 14,400
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:
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