Watlow CAS200 - Manual (Page 28)

Chapter 2: Installation CAS200 User’s Guide
16 Watlow Anafaze
Table 2.1 Cable Recommendations
Noise Suppression
The CAS200’s 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
electromagnetic interference (EMI or noise). If the scanner
is placed close to sources of EMI, it may not function
correctly. Below are some tips on how to recognize and
avoid problems 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 CAS200 case.
Symptoms of RFI/EMI
If your scanner displays the following symptoms, suspect
EMI:
• The scanner’s display blanks out and then reenergizes
as if power had been turned off for a moment.
• The process variable does not display correctly.
EMI may also damage the digital output circuit—so digital
outputs will not turn on. If the digital output circuit is
damaged, return the scanner 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 Dig-
ital I/O
Belden 9539
Belden 9542
Ribbon Cable 9
20
50
24
24
22-14
0.2
0.2
0.5-2.5
Analog Outputs
Belden 9154
Belden 8451 2
2 20
22 0.5
0.5
Computer Communica-
tion: 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)