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Rockwell Automation Publication 440R-UM014D-EN-P - December 2019
Chapter 3
Power, Ground, and Wire
Safety Outputs
The safety outputs consist of two redundant positive-guided relays that are
connected in series. Terminals 11/12 are normally closed monitoring
(non-safety). Terminals 23/24, 33/34, and 43/44 are normally open. The
outputs can drive loads that are either AC or DC powered.
shows
typical connections of the safety outputs to safety contactors.
Figure 8 - Safety Outputs
Derating Curve
The currents through the safety outputs are subject to derating. The derating
depends on the current through each of the outputs and the ambient
shows a graphical representation of the current limit over
the ambient temperature range.
Calculate the total quadratic current, which is the sum of the squares of the
currents through each of the safety outputs.
I
1
2
+ I
2
2
+ I
3
2
=
Σ
I
2
(A
2
)
Then, use the graph in
to find the highest ambient temperature that is
allowed.
Figure 9 - Safety Output Derating Curve
Variable
Description
I
1
, I
2
, I
3
The currents in contact paths 23/24, 33/34 and 43/44
24V DC
or L1 115V AC
or L1 230V AC
24V Com
or L2 (Neutral)
K3
K2
K1
A2
X1 X2
L3
L2
L1
X3
34 44
A1
A3
33
23
11
24
12
ON ERR A4
54
43 53
Total Quadratic Current Σ I
2 (A
2 )
Ambient Temperature (°C)
20
60
70
80
50
40
0
10
20
30
40
60
50
30
10
