ERNITEC PIR-75 Installation Instruction

I
NSTALLATION
1. Introduction
The PIR-75 is a highly sensitive Passive Infrared Detector designed for long range detection outdoors with a
narrow, curtain-shaped differential field of view. It incorporates adaptive threshold discrimination by
feedback of environmental effects and rejection of disturbance signals, flat frequency response and a
computer designed optical system.
The gain can be adjusted with a potentiometer to adapt the sensitivity of each individual unit in function of
the required detection range and according to the specific needs of an installation. Depending on the type
of installation, emphasis can be put on maximum detection or lowest nuisance alarm probability.
2. Mounting and Installation
The mounting structure should be stiff enough to resist significant deflection in windy conditions.
Movement of the PIR-75 caused by vibrations or other movements will result in large swings of the field of
view covered by the PIR-75 and could cause strong disturbance signals. These unwanted signals may lead to
an increase of the alarm threshold level thus reducing the responsiveness or in certain cases producing
unwanted alarms.

It is very important that the back cover of the PIR-75 is securely tightened. It is not sufficient to close
the cover only to the point where the O - ring starts to rub against the inside of the cover. It must be
tightened to the point where it cannot be closed further with reasonable force. There will then be
hardly any gap between the cover and the housing (considerably less than 0.5 mm).
The cable entry assembly should not be changed without authorisation by the manufacturer. It is specifically
designed to allow air entry and exit so that the inside of the PIR-75 is always at atmospheric pressure. This
prevents moisture being sucked into the PIR-75 by drop of internal pressure likely to happen when rainfall
rapidly cools down a unit warmed up in the sun.
The nut on the cable entry assembly should be tightened to clamp the cable in place with the nylon grip. If
the cable diameter is too small to be held by the grip, insulation tape should be wound around the cable to
increase the outside diameter to a suitable size.
3. Connecting the PIR-75
For the definition of the connector board and terminal block see Annex 1.
Alarm Signalling
There are two types of alarm signalling from the PIR-75:

one SPST potential-free relay contact

an open collector transistor to negative supply rail
The relay contact opens and the transistor switches to low resistance on alarm.
Tamper Switch
To detect attempts to open the PIR-75, a tamper switch is fitted for the rear cap. Its contact opens when
the cap is unscrewed and can be connected in series with the normally closed relay contact if no separate
tamper line is used.
Electronics Supply
Ensure that polarity is correct when connecting power to the electronic circuit. Built-in circuitry will
withstand a short period of reversed polarity, but damage will result if this is not corrected quickly.
INSTALLATION INSTRUCTION FOR PIR-75
I
NSTRUCTION
2824-00001 Page 1