Watlow Series PD - Manual (Page 12)

W a t l o w S e r i e s P D
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10
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C h a p t e r 2 I n s t a l l a n d W i r e
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Warning:
Use National Electric (NEC) or
other country-specific standard
wiring and safety practices when
wiring and connecting this con-
troller to a power source and to
electrical sensors or peripheral
devices. Failure to do so may re-
sult in damage to equipment and
property, and/or injury or loss of
life.
Note: Current transformer (CT)
must be purchased separately.
Note: A current transformer input
cannot be associated with a
process output on Output 1 or 3.
Figure 10a — Digital input internal circuit
Dual Current Transformer (CT) Inputs
PD_ 3-_ _ _ _-_ _ _
• Input impedance 100
Ω
, Vac only.
The current transformer (CT) must be purchased separately. Watlow CT
part number is 16-0246 (up to 50 amps).
Systems that are more than 50 amps need an interstage transformer. For
example, if you use a 300 amp CT, part number 16-0073, and an interstage
transformer, part number 16-0176, the 300 amp CT provides a 5 amp signal
to the interstage transformer. In turn, the interstage transformer provides a
20 mA maximum signal to the controller.
Figure 10b — Single Phase
1
2 3 4
1
2
3
CT Common
CT Input 1
CT Input 2
L2
L1
CT
Load wire
Center leg not used
To CT Input 1 or 2
To CT Common
AC Load
CT Input 1 or 2
CT Common
0 to 5A
AC
0 to
20mA
A
Single phase current sensing up to 300 amp
16-0176
Transformer
Digital Input 2 (3)
Digital Input Common (1)
Internal Circuitry
Digital Input 1 (2)