Watlow F4T - Page 19

Watlow F4T Install & Troubleshooting • 16 • Chapter 2 Install and Wire
Example: Using a Current Transformer
Controller
Output N
CT Input
L2 L1
Fuse
SSR
3A x 4
12A
48mA
48mA
12A
x 4 = 48A
Turns around CT
Turns around CT
CT Primary Current
CT Secondary Current
Total current
CT Ratio R = 1000:1
:
I
s
= I
p
T/R = 50mA
ISC = Ip(full scale) = 50mA(R)/T
CSI = Output N
I
s = Current in secondary of current transformer
I
p = Current in primary of current transformer
T = Number of turns through the primary of the transformer
R = Number of turns in the secondary of the current
transformer (Turns ratio, assuming one primary turn)
ISC = Input Scaling (parameter found in Current function block)
CSI = Current Output Source Instance (parameter found in Current function bloc
k)
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