Flame Detection Operation
Benefits of the S200+ Series
Design of System
SYSTEM DESIGN INFORMATION
Approvals and Compliance with Standards
Mounting a Detector
Initial Wiring Check
Connecting and Commissioning the
CONNECTING S241+ AS A CURRENT SOURCE DEVICE
SECTION A 1.
The S200+ range of triple IR flame detectors comprises five flame detector variants. The detectors share the same flame detection circuitry, optics and main mechanical housing. Each variant is available as an Intrinsically Safe (i) or Flameproof (f) version except the S261+ which is available only in the Flameproof version. The five variants are:
Conventional 2-Wire Interface
4-20mA Current Loop Interface
Analogue Addressable Loop Interface
MX Digital Interface
The S200+ Advanced Flame Detector offers a major improvement in both flame detection capability and immunity to blackbody radiation. The S200+ is available in intrinsically safe and flameproof models except for the S261f+ which is available only as a flameproof version. In particular, the range incorporates models for conventional detection circuits (S231i+, S231f+), models for connection to 4-20 mA current loop (S241i+, S241f+), models for connection to Thorn Security Minerva analogue addressable systems (S251i+, S251f+), a flameproof model with relay outputs (S261f+) and models for connection to Minerva MX Digital systems (S271i+, S271f+). The output of the S241+ provides a truly analogue current output and the S251+ and S271+ provide an additional level of signalling to indicate a pre-alarm condition. The detectors have been tested by LPCB to EN 54 : Part 10 and have been classified as Class 1 flame detectors on the 50m and 25m range settings and as Class 3 on the 12m range setting. For marine applications, the detectors have been tested to Lloyd’s Register Test Specification Number 1 (2002). Environmental Category ENV1, 2, 3 and 5 and to DNV Certification Notes No.2.4 (April 2001).
FLAME DETECTION OPERATION
The S200+ detectors analyse radiant energy at three different wavelengths and as such offer the full benefits of the triple IR flame detector. The detector uses a well proven, flame detection technique. This is based on monitoring for modulated infra-red radiation in the 4.3μm waveband corresponding to CO2 emission. It incorporates Thorn Security patented techniques for improved rejection of solar energy by using a combination of two 4.3μm filters for Gaussian noise rejection by averaging the output signal of two separate sensor elements. Three different alarm delays of 3s, 6s and 12s are provided in all versions of the S200+.
The S200+ implements a new concept for eliminating nuisance alarms from modulated blackbody sources. The new design incorporates a novel optical filter(1) which enables a single electronic infra-red sensor to measure the radiated energy present in two separate wavebands placed on either side of the flame...
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