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900 Series V5.0: Installation Guide, April 1999
The following points must be taken into consideration:
•
Each barrier fed circuit must be a separate circuit and must not be interconnected
with any other electrical circuit.
•
The electrical circuit in the hazardous area must be capable of withstanding an AC
test voltage of 500 V RMS to earth or frame of the apparatus.
•
The installation must comply with national installation requirements.
•
The capacitance and either the inductance or the resistance (L/R) ratio of the
hazardous area cable must not exceed the parameters specified in the table blow.
Table 4: Limits for energy stored in cables
Group
Capacitance
(µF)
Inductance
(mH)
Ratio (µH/Ohm)
II C
0.13
4.2
55
II B
0.39
12.6
165
II A
1.04
33.6
440
•
The cable can be separate cables, a twin pare, a pair contained in a type ‘A’, or a
type ‘B’ multi-core cable provided that the peak voltage of any circuit contained
within the multi-core does not exceed 60 V.
•
Special conditions might apply when using AC barriers.
•
An external Light Emitting Diode (LED) can be fitted to terminals L2 and +R of a fire
monitor. The surface area of the LED must lie between 20 mm² and 10 cm². The
LED and its terminals must have a degree of protection of at least IP20, and must be
segregated from other circuits and conductors.
Any system installed within the parameters specified above must be marked in
accordance with BS5501: Part9 (EN50 039). The marking must include at least
"ApolloXP95 I.S. Fire Detection System, BASEEFA No. Ex94C2444SYST".
In safe area (standard) applications it is normal practice to connect the wiring as a loop,
with both ends terminated at the control panel. In the event of an open-circuit fault it is
then possible to drive both ends simultaneously. In a hazardous area
you must not use
a loop configuration
because the potential to feed power from each end of the loop
would double the available energy in the hazardous area and contravene the energy
limitations of the Intrinsically Safe certification. All Series 970 Intrinsically Safe circuits
must therefore be connected as spurs from the safe area loop or as radial connections
from the control panel.
It is recommended, for the highest system integrity, that each Intrinsically Safe circuit is
restricted to a single zone and that the connection from the safe loop to the Intrinsically
Safe spur is protected on each side by Series 950 isolators. This configuration, shown in
Figure 26: Schematic wiring diagram of Intrinsically Safe zone, conforms fully to the
requirements of BS5839: Part I and with the draft European Guidelines prEN54: Part 14
as a single wiring fault will result in the loss of only one zone of detection.
This arrangement can include single or dual-channel translators, housed together with
the critical wiring, in a robust mechanical enclosure. For further advice, please contact
your local Technical Support Department at Aritech.
