GE Industrial Solutions EntelliPro ES - Manual (Page 16)

CHAPTER 1: INTR ODUCTION
1.8 EP OS MOTOR MANAGEMENT SYSTEM – INSTRUCTION MANUAL
1.1.5 EntelliPro ES Current Transformer Definition
Four unique current transformer catalog numbers are offere d:
Use of the minimum number of primary turns is recommended.
would set the FLA range from 52.5 amps (315/6) to 315 amps. So, 77 amps could be selected.
77 amp example is to use an EntelliPro CT 630 with two primary turns. The nominal CT current = 630 / 2 = 315 amps. This
This case would require using multiple turns on the CT primary (see figure 1-2 and equation below). The solution to the
would result in the lowest FLA setting of 630/6=105 amps, which is too large for this application.
when trying to protect the motor load level at 77 amps, the EntelliPro CT 64 is too small. Considering the EntelliPro CT 630
There may be cases where the available transformer types have inappropriate ranges for the application. For example,
increments.
EntelliPro CT 64 transformer is chosen, the FLA setting can be configured from 64/6=10.7 amps to 64 amps in 0.1 amp
Use of the appropriate transformer will allow the FLA setting to be configured in the range of CT/6 to CT. For example , if the
consider are the transformer type, the number of primary windings, and the EntelliPro ES full load current setting (FLA).
There are three items that must be considered when configuring the motor load level of the EntelliPro ES. The items to
EntelliPro CT 8
EntelliPro CT 32
EntelliPro CT 64
EntelliPro CT 630
The CT catalog configuration definition is shown below:
EntelliPr o CT 8
Current Transformer Designator
accuracy).
current ranges and
(refer to section 1.2.3 for
Example using EntelliPro CT 8 as 2A CT
Nominal CT Currente
# of primary loops = 8/2 = 4 Turns
Calculating # of primary loops required
In addition, these CTs can be used as interposing CTs to increas e the primary current.
Nominal Current (CT with loops) =
Nominal CT Current
# of loops
Figure 1-2: Primary feeding loops