Technical Reference Manual – SB-293
Printing Date
01838-002 Rev. 3.0
July-1998
Page 29 of 32
RELAY, FORM C
– a device that has both normally closed and normally open circuits. When the
relay is not energized, the normally closed circuit is complete and the normally open circuit is
open. When the relay is energized the circuits switch roles, the normally closed circuit is open
and the normally open circuit is complete. This dual nature of Form C relays allows for two types
of applications outside the controller. A device may be attached to the normally closed circuit so
that it is always on until the relay energizes to open the circuit and turn it off. Or, a device may
be attached to the normally open circuit so that it is always off until the relay energizes to turn it
on.
REQUEST TO EXIT
– a signal that informs the controller that someone has requested egress from a
secure area. RTE and REX are common abbreviations.
REX
– see REQUEST TO EXIT.
RTE
– see REQUEST TO EXIT.
SUPPRESSION
– the addition of a device to an electrical circuit that minimizes or prevents transients
from affecting the proper operation of that circuit.
TRANSIENTS
– electrical surges or spikes conducted through power or data lines. Transients are
generated as electrical devices are turned on or off.
TRANSORB
– an electrical suppression device. See SUPPRESSION.
GLOSSARY
