Rockwell Automation 1791-XXXX Discrete I/O AC and DC Block I/O Input and Output Modules - Manual (Page 18)

I/O Interface and System Design
Chapter 2
2-8
Relay Output
The relay outputs on block I/O modules are electro-mechanical outputs and
do not require specific compatibility with the load device as to current
sinking or sourcing.
Figure 2.10
Simplified Schematic of Relay Output Circuit
Indication
LED
(logic)
System
Circuitry
12477-I
L1
L2
20-132V ac
R
L
Output
Common
Input/Output
+5V
100 Ω
0.033 µ F
1k Ω
The 16- and 32-point ac and dc block I/O modules are internally fused to
protect the module. No external power fusing is required. Outputs are not
fused. Fusing of outputs is recommended. If desired to fuse an output, you
must provide external fusing.
Table 2.B
Recommended Fuses
Type of
Circuit
Part Number 1 Size
Rating in
Amps
Maximum Surge Current 2
(repeatable every 2s)
ac
SANĆO SS2Ć1.0 0.25 in. x 1.25 in. 1.0A 3.0A for 50ms
ac
SANĆO MQ2Ć1.0 5mm x 20mm 1.0A 2.5A for 50ms
dc
Littelfuse 322 1.25 0.25 in. x 1.25 in. 1.25A 2.25A for 50ms
dc
SANĆO MQ4Ć800 5mm x 20mm 800mA 3 2.0A for 50ms
1 Note: Do not substitute another fuse for those listed.
2 The recommended fuses will withstand surges of the above listed currents for the time specified.
3 Current must be limited to 650mA when using this fuse. .
Both ac and dc block I/O modules (except relay output modules) are
derated linearly above 30
o C up to and including 60 o C, as shown in
Table 2.C.
For modules with relay outputs, refer to Appendix A for output current and
surge current ratings.
Fusing