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342 9440500990 Rev D
Contact Expansion Module DECS-250N
By mating conductors of dissimilar metals, galvanic corrosion could
occur which deteriorates connections and leads to signal loss.
Connector screw terminals accept a maximum wire size of 12 AWG. Maximum screw torque is 5 in-lb
(0.56 N•m).
Operating Power
The Contact Expansion Module operating power input accepts either 12 Vdc or 24 Vdc and tolerates
voltage over the range of 6 to 32 Vdc. Operating power must be of the correct polarity. Although reverse
polarity will not cause damage, the CEM-2020 will not operate. Operating power terminals are listed in
Table 45.
It is recommended that a fuse be added for additional protection for the wiring to the battery input of the
Contact Expansion Module. A Bussmann ABC-7 fuse or equivalent is recommended.
Table 45. Operating Power Terminals
Chassis ground connection
P1- – (BATT–) Negative side of operating power input
Positive side of operating power input
Contact Inputs and Contact Outputs
The CEM-2020 (Figure 189) has 10 contact inputs and 24 contact outputs. The CEM-2020H
(Figure 190) has 10 contact inputs and 18 contact outputs.
To follow UL guidelines, a fuse must be implemented in the 2Adc
contact circuits (Outputs 12 through 23) of the CEM-2020H used in
hazardous locations. The suggested fuse size in Adc = (100/Contact
Voltage) with a maximum fuse size of 5Adc.
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