Technical information

Page 71
This new technology uses a laser light source to
launch light signals into an optical fibre. As
pulses travel down the fibre, energy is lost
through scattering. A fraction of the scattered
signal is retained within the fibre. A portion of this
is directed back along the fibre towards the laser
source - this signal is called backscatter. Part of
the back scatter signal (Raman Scattering) is
used to provide accurate remote temperature
measurements at hundreds of points along the
fibre.
The MXF100 uses standard communications
grade optical fibre of the 62.5/125 graded index
multimode type. The temperature range is
predominantly a function of the coating used to
protect the optical fibre as the fibre itself is well
behaved over a temperature range from -50
o
C to
approximately 300
o
C.
Optical fibre itself offers several advantages as a
sensing medium. The signals are immune to
electromagnetic interference thereby ensuring
integrity of readings from electrically noisy areas.
As no electrical current is used in the sensing
fibre and the fibre is relatively inert and dielectric
(non-conducting) medium, it is safe technology to
use in hazardous environments.
Features
• Fibre optic sensor loop up to 2km
• Continuous temperature profiles of
temperature on a PC
• Programmable functions
• Programmable number of fire detection zones
• Multiple and programmable Alarm levels per
fire detection zone
• Variable rate of rise function
• Unrivalled response times
• Optional outputs
• Modbus Serial Data
• Direct to PC
• Volt free contacts
• Insensitive to EMI
• Intrinsically safe sensor
• Uses standard communications grade optical
fibre
• Choice of cable construction
• Cable construction for extreme environments
• High System Integrity
• Automatic failure mode analysis
• Loop break recovery operation
• Diagnostic capability
• Fire progression monitoring
• No cable maintenance
• Modem for remote communications
Technical Specification
The MXF100 system complies with:
• EMCDirective 89/336/EEC
• Low Voltage Directive 72/2/EEC
The MXF100 contains a Class 3a Laser product
and complies with:
• BS7192 (1989)
• American National Standard Z136.2 (1988)
• International Electrotechnical Commission
Standard 825 (1990)
Supply Voltage: 24V d.c. (-6/+12V d.c.)
Power Consumption:20W max
Supply Current: <1A
Fuse Rating: <2A (anti-surge)
Fibre: 62.5/125 graded index multi-
mode
Operating Temp.: 0
o
C to +40
o
C
Storage Temp.: -40
o
C to +65
o
C
Humidity: 0 to 95% RH (non-
condensing)
Product Codes
516.016.111
MXF100 Fibre Optic Linear Heat Detection control
unit c/w 3 tier wall mounted cabinet and PSU.
516.016.112
MXF-SL Sensor Line Thermoplastic sensor cable
(1km reel)
516.016.113
MXF-SS Sensor Tube Stainless Steel Sensor
Cable (1km reel).
Datasheet - Product Code PSF111 “MXF100
Optical Fibre Temperature Sensing Technology”
MXF Optical Fibre Temperature Sensing
MXF100 FUNCTIONAL BL OCK DIAGRAM
INTERNAL
REFERENCE
FIBRE
SWITCH
LASER &
RECEIVER
OPTIC S
CONTROL
POWER
SUPPLY
DATA
ACQUISITION
DATA
PROCESSOR
OPTIC S
ELECTRONIC S
RELAY PCB1
RELAY PCB2
RELAY PCB3
SIGNAL CONTROL
POWER
SIGNAL
24Vd.c.
RELAY CONNECTORS
RS232 PORT 1
TO PC
RS232 PORT 2 MODBUS
OR SERIAL D ATA