Before Installing

Please thoroughly read this manual and applicable sections

of System Sensor’s Projected Beam Detector Application

Guide. Copies of this manual are available from System

Sensor.

General Description

System Sensor Model 6424 is a long range projected beam

smoke detector designed to provide open area protection.

It is to be used with UL-listed, separately supplied power

(4-wire) control panels only. The detector consists of a

separate transmitter and receiver. Smoke entering the area

between the transmitter and receiver causes a reduction in

signal at the receiver. When the obscuration reaches one of

two predetermined thresholds (chosen with a switch in the

receiver), the detector generates an alarm signal. Complete

blockage of the beam causes a trouble signal to avoid false

alarms. Slow changes in obscuration due to a build up of

dirt or dust on the lens of the detector are compensated for

by a microcontroller which continuously monitors the sig-

nal strength and periodically updates the alarm and trouble

thresholds. When the self-compensation circuit reaches its

limit, the detector generates a trouble signal, indicating the

need for service.

Three LEDs at the receiver indicate the status of the detec-

tor: a red LED for alarm, a yellow LED for trouble, and a

pulsed green LED for standby operation. The alarm signal

latches and can be reset by a momentary power interrup-

tion, by using the remote reset input to the receiver if

using the remote test/reset station model RTS451, or with

the local reset button located behind the rear door in the

receiver. A trouble signal automatically resets upon remov-

ing the cause of trouble. In addition to these indicators,

there are four LEDs on both the receiver and the transmit-

ter which are used as a beam alignment aid. No additional

equipment is needed for alignment of the beam.

Each detector contains one Form A (normally open) con-

tact for alarm signals and one Form B (normally closed)

contact for trouble signals. Supervision of power is accom-

plished by installing a Power Supervisory End-of-Line Relay

Module (model A77-716) at the end of the detector power

loop. When power is applied to and through the detectors,

the EOL Power Supervisory Module is energized. The relay

contacts, along with the detector’s trouble relay contacts,

can provide a closed series circuit in the control panel’s

alarm-initiating loop. A loss in power or a trouble condition

at the detector causes the respective EOL or trouble relay to

open, resulting in a trouble signal at the control panel.

Parts List

Description

Quantity

Receiver Unit

1

Transmitter Unit

1

Receiver Wiring Cable

1

Transmitter Wiring Cable

1

Wall Mounting Bracket

2

Ceiling Mounting Bracket (inside part)

2

Ceiling Mounting Bracket (outside part)

2

Wall Bracket Screw

2

Ceiling Bracket Screw

2

Washers

4

Allen Wrench

1

Instruction Manual

1

Test Filter

1

Cable Exit Plug

1

Hole Plug

1

Detector Placement

This section of the manual discusses the placement of pro-

jected beam detectors. Though this information is based

upon industry expertise, it is intended to be used only as

a technical guide. Always comply with the requirements of

applicable codes and standards such as, NFPA 72, National

Fire Alarm Code, as well as directives of the Authority

Having Jurisdiction (AHJ). For general information on

the placement of detectors, read System Sensor’s Projected

Beam Detector Application Guide.

Projected beam detectors are usually located with their

beams parallel to the ceiling. However, they can be mount-

ed vertically or at any angle to protect the area involved.

Since beam detectors sense the smoke buildup over a dis-

tance, they are ideal for locations with high ceilings. They

can also be mounted on a wall or ceiling below the level

of a spot type detector, reducing the effects of air stratifica-

tion. Some typical locations would include large areas with

high ceilings such as atriums, warehouses, and factories.

NOTE: Projected beam smoke detectors should always

be mounted to stable mounting surfaces. See the

MOUNTING LOCATION section for details.

Some fire codes specify spacing on a given center-to-center

distance between detectors under ideal conditions. These

spacings are based on rooms with smooth ceilings and no

physical obstructions between the contents being protected

and the detectors. Moreover, they are also based on a maxi-

mum ceiling height, and on the assumption that the value

and the combustible nature of the contents of the room

being protected do not warrant greater protection or closer

spacing.

D400-18-00

2

I56-494-13R

PRINTED IN MEXICO