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Chapter 2
GuardLink System Design
R 1
I 1
Fuse
Link Cable
4 A
SLO-BLO™
L 1
V J1
+ + - -
Vs=24V
Power
Supply
System Current Calculation
24
Figure 6 - Tap Connections
D1
Safety Device 1
Device Cable
J3
R 2
INPUT
I 2
Link Cable
J1
J2
L 2
T1
V J2 V J3
Table 3 - Key for
Item
D1, D2, D3
I
, I
, I
1
2
3
I
, I
, I
T1
T2
T3
I
, I
, I
D1
D2
1D3
L
, L
, L
1
2
3
R
, R
, R
1
2
3
T1, T2, T3
V
, V
, V
J1
J2
J3
The GuardLink circuit current must be calculated to determine whether a
significant voltage drop occurs to a safety device.
The total system current, I
plus the current required by the device that is connected to the first tap plus the
current required by the downstream circuit. The total system current must not
exceed 4 A, continuous.
I
= I
1
The current in each segment of the GuardLink circuit is calculated in a similar
fashion.
I
= I
2
I
= I
3
The total system current, I
sum of the tap currents.
I
= Σ I
1
Rockwell Automation Publication 440R-UM015C-EN-P - April 2018
D2
Safety Device 2
Device Cable
J3
INPUT
I 3
Link Cable
J1
J2
T2
Figure 6
Description
Safety devices
Current in the link cable (A)
Current required by a tap (A)
Current required by a safety device (A)
Length of link cable (m)
Resistance of wire (Ω)
Taps
Voltage at tap connector (V)
, is the sum of the current required by the first tap
1
+ I
+ I
T1
D1
2
+I
+ I
T2
D2
3
+ I
T3
D3
, is therefore the sum of the device currents plus the
1
+ Σ I
T
D
Device Cable
J3
R 3
INPUT
J1
J2
T3
L 3
Safety Device 3
D3
Terminator
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