5 Dry Contact Alarm (Failsafe)
The dry contact relay alarm is available to indicate when an interface
communication become unavailable or the equipment lacks from one of its power
supplies, as an energy fault or any power sources removal.
The dry contact connections are illustrated below and insulated flexible wires of 1.5
mm² cross section shall be used.
Figure 96: Failsafe Relay
The fail safe works in a combination of three pins, in which the pin 2 is the common
one:
When the equipment is healthy, contact 2-3 is normally closed, contact 2-1
is normally open;
When the equipment is faulty, contact 2-3 is open, contact 2-1 is closed;