System Sensor PDRP-1001 User Manual

Initiating Device Circuits

2. Installation

PDRP-1001 Instruction Manual  PN 50734:D0  04/06/01

19

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 the "Appendix B: Compatible Devices" on page 39 for suitable 4-wire smoke detectors.

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    

Rmax =

(20.6 - Vom)

(N x Is) + (Na x Ia) + (Ir)

–

–

+

+

–

–

+

+

TB1

TB4

IN #1

B+  A+  A–  B–

       IN 

B+  A+

MS

44

-4

wir

esd

.cd

r

24 VDC Four-wire 

Smoke Detectors

4.7K, 1/2-Watt ELR
PN 71252 (UL listed)

Power 
Supervision 
Relay
(A77-716B)

Style B

Initiating Device Circuit

Control Panel 

Power Circuit