The Context Plus XP95 input/output unit provides two voltage-free, single pole, change-over relay outputs, a single monitored switch input and an unmonitored, non-polarised opto-coupled input. Compliant with EN54-17 & 18 (2005), the Input/Output Unit supervises one or more normally-open switches connected to a single pair of cables. It is set to return an analogue value of 4 in the event of an open or short-circuit fault and 16 during normal operation. The status of the inputs is reported by means of two input bits. The change-over contacts are operated by an output bit. The Input/Output unit is fitted with a bi-directional short-circuit isolator and will be unaffected by loop short-circuits on either loop input or output. Electrical Considerations The unit operates at 17-28V DC with protocol voltage pulses of 5-9V. No electrical supply greater than 50V AC rms or 75V DC should be connected to any terminal. Designed for indoor use only it includes four LEDs, two red and two yellow, which are visible through the front cover of the enclosure. One red LED is illuminated to indicate that the relay is set. The second red LED is illuminated to indicate that the switch input is closed. One yellow LED is illuminated whenever a fault condition (open or short circuit) has been detected. The other LED is illuminated whenever the built-in isolator has sensed a short-circuit loop fault. The enclosure is moulded from white self-extinguishing polycarbonate....

The Context Plus XP95 Zone Monitor powers and controls the operation of a zone of up to 20 Series 65 conventional fire detectors from a loop of Context Plus analogue addressable detectors and interfaces. The Zone Monitor is factory preset to return an analogue value of 16 when all detectors on the zone are in quiescent state and 64 when a detector changes to the alarm state. The Zone Monitor latches in the alarm state. 5.1kΩ end-of-line resistor is fitted to detector cables for open- and short-circuit faults. Alternatively, an active end-of-line monitor may be used in conjunction with diode bases and a capacitor of up to 50µF fitted at the Zone Monitor wiring terminals. In either case an analogue value of 4 is transmitted during open- or short-circuit faults. The Zone Monitor is fitted with a bi-directional short circuit isolator and will be unaffected by loop short circuits on either the loop input or loop output. Electrical Considerations The Zone Monitor is loop powered and operates at 17–28V DC with protocol pulses of 5–9V. Mechanical Construction The Zone Monitor is supplied with a backbox for surface mounting, and is also available without the backbox for flush mounting. Both versions are for indoor use only. Two LEDs, one red and one yellow, are visible through the front cover of the enclosure. The red LED is illuminated to indicate that a fire alarm condition has been detected on the zone wiring. The yellow LED is illuminated whenever the built-in isolator has sensed a short circuit loop fault. Notes On Use Zone voltage is regulated to 19 ± 1V for any loop voltage greater than 22V. If the loop voltage falls below 22V, the zone voltage is approximately 1.5V below the loop voltage. It is important to ensure that under worst-case conditions, the zone voltage is above the minimum operating voltage for the conventional detectors. Alarm conditions are latched internally by the Zone Monitor. It is therefore necessary to reset the alarm even if non-latching conventional detectors are used. Manual call points can be located at any point in the zone wiring if active end-of-line monitoring with diode detector bases is used. If a 5.1kΩ resistor is used for monitoring, manual call points must be connected between the Zone Monitor and the first detector....

Our DIL Switch Addressed (DSA) Context Plus temperature detectors have a low air flow resistance case made of self-extinguishing white polycarbonate. The devices monitor temperature by using a single thermistor network which provides a voltage output proportional to the external air temperature. The response to heat increases of the standard temperature detector enables the detector to be utilised as an EN54–5:2000 A2S heat detector, which is equivalent to an EN54–5:1984 Grade 2 detector. A high temperature detector, which has similar characteristics at 25°C but reaches a 55 count at 90°C, is available for use in normal ambient temperatures of up to 55°C. This detector meets the requirements for a CS detector in EN54–5:2000. The address of DSA Context Plus temperature detectors is set using the DIL switch located on the underside of the device. All segments are set to 0 (ON) or 1 (OFF), using a small screwdriver or similar tool. The address should be written on the label and the rear of the detector sealed....

Our DIL Switch Addressed (DSA) Context Plus optical detector has a moulded self extinguishing white polycarbonate case designed to allow free entry of smoke while minimising the effects of dust contamination. Stainless steel wiper contacts connect the detector to the terminals in the mounting base. Within the case is a printed circuit board which on one side has the light proof labyrinth chamber with integral gauze surrounding the optical measuring system. The other side has the address capture, signal processing and communications electronics. The address of the DSA Context Plus detectors is set using the DIL switch located on the underside of the device. All segments are set to 0 (ON) or 1 (OFF), using a small screwdriver or similar tool. The address should be written on the label and the rear of the detector sealed....

  Context Plus XP95 temperature (heat) detectors have a common profile with ionisation and optical smoke detectors but have a low air flow resistance case made of self-extinguishing white polycarbonate. They monitor temperature by using a single thermistor network which provides a voltage output proportional to the external air temperature. The response to temperature increases of the standard temperature detector (part no: 55000-400IMC) enables the detector to be utilised as an EN54 Grade 2 heat detector. To provide a device for use in ambient temperatures of up to 55°C, a high temperature detector (part no: 55000-401IMC) is also available. This has similar characteristics to the standard temperature detector at 25°C but reaches a 55 count (alarm) at 90°C....

The Context Plus XP95 optical detector uses the same outer case as the ionisation smoke detector and is distinguished by the indicator LED which is clear in standby and red in alarm. Within the case is a printed circuit board which, on one side, has the light proof labyrinth chamber with integral gauze surrounding the optical measuring system and, on the other, the address capture, signal processing and communications electronics. An infrared light emitting diode within its collimator is arranged at an obtuse angle to the photo-diode. The photo-diode has an integral daylight-blocking filter. The IR LED emits a burst of collimated light every second. In clear air the photodiode receives no light directly from the IR LED because of the angular arrangement and the dual mask. When smoke enters the chamber it scatters photons from the emitter IR LED onto the photo-diode in an amount related to the smoke characteristics and density....