GAS Gasmaster, Installation, Operation And Maintenance Manual

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The Gasmaster power supply contains no user
replaceable fuses.
Short circuit protection
Each detector input is short-circuit protected. Self-
resetting ‘polyfuses’ are fitted to the 24 V power supply
which will cut power in the event of a cabling fault,
and automatically reset when the fault is corrected.
Detectors with a maximum consumption of 500 mA
may be connected.
Circuit breaker
If the equipment is permanently connected to a
mains supply then a dedicated circuit breaker must be
included in the installation, to comply with EN 61010-
1. The circuit breaker must be close to Gasmaster, in
easy reach of the operator. It must be marked as the
disconnecting device for the Gasmaster system, and
the ON and OFF positions must be clearly marked.
The circuit breaker must comply with the relevant
requirements of IEC60947-1 and IEC60947-3. The
protective earth must not be disconnected even when
the breaker is activated.
Figure 2.2 Gasmaster chassis plate with display PCB
board and batteries.
2.3 Mounting
All Gasmaster systems should be installed in a safe area.
Consider location, cabling and earthing requirements.
Figure 2.3 provides a dimensional view of Gasmaster.
To access the mounting points, first remove the front
cover by unscrewing the fixings labelled
➁
in figure
2.1. Carefully remove the sounder connector from
the display PCB. The cover should be placed in a
secure location. It is recommended that Gasmaster is
positioned by hand in the desired location, and a pencil
used to mark the mounting hole positions. Gasmaster
should be removed before drilling the mounting
holes. Nylon bushes suitable for up to 5mm screws are
fitted within the Gasmaster mounting points. Ensure
these bushes are present when mounting as they are
essential to maintain the ingress protection of the
enclosure.
Figure 2.3 Dimensional view of Gasmaster with
mounting holes shown
2.4 Cabling requirements
Cabling to Gasmaster and detectors must be in
accordance with the recognised standards of the
appropriate authority in the country concerned, and
must meet the electrical requirements of the detector.
• Explosion-proof (Exd) devices
Gas Alarm Systems recommends the use of steel wire
armoured (SWA) cable. Suitable explosionproof glands
must be used.
• Intrinsically Safe (I.S.) devices
Gas Alarm Systems recommends the use of twisted
pair cable with overall screen and sheath. Suitable
weatherproof glands must be used. I.S. devices must be
used with a suitable Zener Barrier or Galvanic Isolator
when used in a hazardous area.
2. Installation