Crowcon Crowcon Gasmaster, Installation, Operation And Maintenance Manual, Page: 9 / 48

Crowcon Gasmaster Installation
5
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 posi-
tions 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
Batteries
Battery connection
diagram
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
 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 pro-
tection of the enclosure.
Figure 2.3
278
288
110
77
Mounting holes
214
120
5
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
Crowcon recommends the use of steel wire
armoured (SWA) cable. Suitable explosion-
proof glands must be used.

Intrinsically Safe (I.S.) devices
Crowcon recommends the use of twisted pair
cable with overall screen and sheath. Suitable
weatherproof glands must be used. I.S. devic-
es must be used with a suitable Zener Barrier
or Galvanic Isolator when used in a hazardous
area.