925-0292 Rev C
7
2.3
Grounding
An equipment grounding connection (earth ground) must be supplied to the unit for safety. Connect the ground
conductor to the green equipment grounding screw identified in the enclosure.
3.0
DPDT RELAY
The DPDT relay utilizes a Fail Safe selector switch. There are 2 positions for this switch, High (H) and Low (L). A
Fail-Safe condition means that the DPDT relay contact positions are set up so that in the event of a power failure
the relay will be de-energized and the contacts will indicate a condition that is deemed safe for the application.
3.1
Fail-Safe High
Fail-Safe High means that the relay will be energized when the paddle is rotating (uncovered) and will de-energize
when the probe is covered. In this mode, a power failure will cause the relay contacts to indicate that the paddle is
covered, whether it is or not.
Figure 7
3.2
Fail-Safe Low
Fail-Safe Low means that the relay will be de-energized when the paddle is rotating (uncovered) and will energize
when the paddle is covered. In this mode, a power failure will cause the relay contacts to indicate that the paddle
is uncovered whether it is or not.
Figure 8
NC C NO NO C NC
1
1
1
2
2
2
NC C NO NO C NC
1
1
1
2
2
2
UNCOVERED
COVERED
FAIL SAFE "HIGH" RELAY CONTACT POSITION
NC C NO NO C NC
1 1
1
2
2 2
NC C NO NO C NC
1
1
1
2 2
2
UNCOVERED
COVERED
FAIL SAFE "LOW" RELAY CONTACT POSITION
