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7
PRSU/4, PRSU/5 Operating Instructions Manual (Revision 3.0)
Monitoring Channel Mode Wiring
For both of the following configurations, please note the maximum and
minimum electrical parameters for these devices listed in the table on Page 10.
1. Dual channel (fail-safe):
For fail-safe (safety) applications, the following configuration must
be used:
Fail-Safe / Dual channel
This configuration ensures that the full length of all switch/sensor
conductors are
monitored. If the switch/sensor’s conductors are
compromised at any point along their length, the controller will detect the
fault and cause the output relay to de-energize.
Warning: For this configuration to work as intended, the series
resistance between each end of the sensor’s conductors cannot exceed
10
Ω. Additionally, the short circuit resistance between both of the
switch/sensor’s conductors cannot exceed 200Ω.
(Up to Category 3, SIL2, PLd Unreachable).
2. Single channel (Non-Safety):
For non-failsafe applications (non-safety), utilize the following
configuration where one side of each switch/sensor´s conductors is
connected to a monitoring terminal:
Single Lead / Single channel
Warning: This configuration does NOT provide detection of a
broken conductor/malfunctioning switch and is therefore
unsuitable for safety-related applications. For such applications, do
NOT use this configuration and opt for a “Dual Channel” fail-safe
configuration instead.
Figure 7: Dual-Channel (With Wire-Break Safety) Configuration
Figure 8: Single-Channel (Non-Safety) Configuration
