Four-Wire Smoke Detector Connections - System Sensor PDRP-1002 Series Instruction Manual

Initiating Device Circuits

Four-Wire Smoke Detector Connections

A maximum of 200mA is available from the 24VDC Resettable Power circuit on TB1 (+24VR terminals).
Any power that is drawn from the 24VDC Nonresettable Power on TB2 (+24VNR terminal) must be
subtracted from available resettable power. See "Specifications" on page 12 and "Powering External
Devices" on page 22.
Note: Refer to "Appendix B: Compatible Devices" on page 41 for suitable 4-wire smoke detectors.
Notes on Style D (Class A) and Style B (Class B) field wiring:
1. The Power Supervision Relay coil leads must be connected to the last detector base 24V screw
terminals.
2. Calculation of the maximum allowable resistance in the 24VDC resettable power wiring:
Where:
Rmax = maximum resistance of the 24 VDC wires
Vom = minimum operating voltage of the detector or end-of-line relay, whichever is greater, in volts
N = total number of detectors on the 24 VDC supply circuit
Is = detector current in standby
Na = number of detectors on the 24 VDC power circuit which must function at the same time in alarm
Ia = detector current in alarm
Ir = end-of-line relay current
Power
Supervision
Relay
(A77-716B)
PDRP-1002 Instruction Manual PN 51135:B0 04/06/01
Rmax =
4.7K, 1/2-Watt ELR
–
+
–
+
24 VDC Four-wire
Smoke Detectors
Figure 8 Typical Connection for Four-Wire Smoke Detectors
(20.6 - Vom)
(N x Is) + (Na x Ia) + (Ir)
–
+
–
+
TB 1
Control Panel
Power Circuit
2. Installation
TB 4
IN # 1
IN
B + A + A – B – B + A +
Style B
Initiating Device Circuit
19