Watlow CPC400 - Manual (Page 35)

CPC400 Series User’s Guide Chapter 2: Installation
Doc. 0600-2900-2000 Watlow Anafaze 21
Table 2.1 Cable Recommendations
Noise Suppression
The CPC400 outputs are typically used to drive solid-state
relays. These relays may in turn operate more inductive
types of loads such as electromechanical relays, alarm
horns and motor starters. Such devices may generate elec-
tromagnetic interference (EMI, or noise). If the controller is
placed close to sources of EMI, it may not function correct-
ly. Below are some tips on how to recognize and avoid prob-
lems with EMI.
For earth ground wire, use a large gauge and keep the
length as short as possible. Additional shielding may be
achieved by connecting a chassis ground strap from the
panel to CPC400 case.
Symptoms of Noise
If your controller displays the following symptoms, suspect
noise:
• The display screen blanks out and then reenergizes as
if power had been turned off for a moment.
• The process variable value is incorrect on the control-
ler display.
Noise may also damage the digital output circuit such that
the digital outputs will not turn on. If the digital output cir-
cuit is damaged, return the controller to Watlow Anafaze
for repair.
Function Mfr. P/N
No. of
Wires
AWG mm
2
Maximum
Length
Analog Inputs
Belden 9154
Belden 8451 2
2 20
22 0.5
0.5
—
RTD Inputs
Belden 8772
Belden 9770 3
3 20
22 0.5
0.5
—
Thermocouple Inputs T/C Ext. Wire 2 20 0.5 —
Control Outputs and
Digital I/O
Belden 9539
Belden 9542
Ribbon Cable 9
20
50
24
24
22 to 14
0.2
0.2
0.5 to 2.5
—
Analog Outputs
Belden 9154
Belden 8451 2
2 20
22 0.5
0.5
—
Computer Communi-
cation: EIA/TIA-232,
422 or 485, or 20 mA
Belden 9729
Belden 9730
Belden 9842
Belden 9843
Belden 9184 4
6
4
6
4 24
24
24
24
22 0.2
0.2
0.2
0.2
0.5 4000 ft. (1219 m)
4000 ft. (1219 m)
6000 ft. (1829 m)