GJD D-TECT 2 External Quad PIR Detector, White, Up to 30m GJD300W

What this PIR detector is for

Outdoor detection often fails in one of two ways: it misses people, or it fires on things that do not matter. This GJD PIR detector is built to reduce false alarms while covering a defined patch of ground.

It suits CCTV and alarm installers protecting yards, car parks and building perimeters. The white housing may suit pale walls.

How does a quad PIR detector work?

PIR stands for passive infrared. It sends out nothing itself, and instead reacts to heat moving across its view.

• Fresnel lens: this ridged lens splits the view into zones, 28 for each pair of heat-sensing elements (GJD calls this a Pyro pair). A warm body crossing those zones produces the signal the detector looks for.
• Pulse count: set from 1 to 3, this is how many signals are needed before it triggers. A higher number means fewer false alarms, while a lower one means faster response.
• Shielded optics: double silicon shielding filters out white light, so bright light such as headlights is less likely to cause a trigger.
• Temperature compensation: digital sensitivity adjustment helps it stay steady as outdoor conditions change.

Where to use it

It is a wired external detector for walls and poles. With its IP65 rating and -20ºC to +55ºC range, it covers most UK outdoor conditions.

A typical job is starting a camera recording when someone crosses a yard, or signalling a GJD lighting control system to light a side path.

What the figures mean in practice

• Up to 30m range: because the range is programmable, the detection pattern can end before a road or a neighbour's land.
• 10º - 70º detection angle: this is the coverage spread, up to 30m x 30m. Check the beam patterns against the area you need to cover.
• 50,000 Lux: lux measures light falling on a surface, and this is a very bright level.
• 2 to 60 second timer: a timer normally sets how long an output stays on after detection, which is useful when triggering a camera or a light.
• Dusk (2 Lux) to 24 hour: choose night-only operation for lighting, or all day for security.

Installing it

• Height and tilt: GJD's D-TECT 2 suits three set-ups. Use 3 m with 0 degree tilt for the multi-beam optimum, 1.5 m with -2 degree tilt for pet immunity, or 6 m with -45 degree tilt for curtain coverage.
• End of line resistors: these let an alarm panel tell a healthy circuit from a cut or shorted cable. They are built in, so there are none to solder on.
• Cable runs: thicker conductors are specified for the longer run because voltage drops over distance. Keep this in mind on long supplies with several devices.
• Accessories by code: options include the GJD304 conduit adaptor, GJD308 D-Guard, GJD380 walk tester and PMB1 pole mount bracket.
• Testing: the output test mode lets you walk the zone and check its edges before leaving site.

Planning your system

Allow for each detector's current in your supply, and add a panel, video system or lighting controller to act on the outputs.

The volt-free outputs are solid state and carry no voltage of their own, so check they match your input. The negative switched outputs suit inputs looking for a switched 0 V signal, and the tamper circuit should go back to a monitored input.

Standards and ratings explained

• BS8418: the British code of practice for CCTV systems set off by detectors and monitored remotely.
• IP65: dust tight, and protected against low-pressure jets of water from any direction.