54
Johnson Controls, Inc. SLC Wiring Manual —
P/N 51870:G 04/23/2009
Power Considerations
Supervising 24 VDC Power
A.2 Supervising 24 VDC Power
There are options for supervising 24 VDC power, as discussed below.
•
Using FlashScan Type Codes with Built-In Power Supervision (IFC-3030 only)
•
Power Supervision Relay
•
Using the M300CJ module without relay
A.2.1 Using Type Codes with Built-In Power Supervision on
IFC-3030
Certain FlashScan type codes have external power supervision built into the software. For details,
refer to “Devices Requiring External Power Supervision” in the appropriate installation manual
.
A.2.2 Power Supervision Relay
Power used to supply 24 VDC detectors, notification appliances (using the M300CJ) and two wire
detectors (using the M302MJ) can be supervised with a power supervision relay. This relay,
energized by the 24 VDC power itself, is installed at the end of each respective power run and
wired in line with the supervised circuit of any intelligent module.
When power is removed from the relay, the normally closed contacts open the supervised circuit,
generating a trouble condition. Therefore, the relay needs to be installed at the end of the
supervised circuit, so as to not disrupt the operating capability of all the devices on that circuit. The
relay can be installed in line with any leg (+ or –) of the supervised NAC or IDC circuit, either a
two or a four-wire style.
See Figure A.1 and Figure A.2. Refer to the
Device Compatibility Document
for compatible
notification appliances and relays.
Figure A.1 Supervised 24 VDC Circuit
SL
C-
ps
rt
p
H
.c
dr
24 VDC Power from
Control Panel or
Power Supply
Power Supervision
Relay
(EOLR-1)
Supervised NAC or IDC
ELR
(Use 47K with M300CJ
or 3.9K with M302MJ)
Last device on the SLC loop
(M300CJ or M302MJ)
