cable length between alarm panel and input should not
exceed 100 Metres. Alarm panels accept a mains electri-
cal power supply cable of 2.5 sq mm, and all other termi-
nals accept a maximum cable size of 1.5 sq mm.
1.7.3 Standby battery (See figure 1.6)
The power supply PCB also contains a standby battery,
battery charging and power fail detection circuits. The bat-
tery provides power for both the SYSTEM ALARM indica-
tion and the audible warning in the event of an electrical
power failure. The battery is fully charged after 72 hours
and provides sufficient power to operate the specific
alarm indications for a minimum of 4 hours. The battery is
expected to have a minimum 5 years life.
1.7.4 LED Status indicators
The power PCB has five LED’s to indicate the following
conditions to help with fault diagnostics:-
LED1 is a “heartbeat” indication, and will normally flash
green. When the power has failed, the LED will be off. If
the software identifies the incorrect board, the LED will be
solid red.
LED2 will blink green when the RS-485 is transmitting
data, off when no activity.
LED3 will blink red when the RS-485 is receiving data, off
when no activity.
LED4 will blink green when the RS-232 is transmitting
data, off when no activity.
LED5 will blink red when the RS-232 is receiving data, off
when no activity.
See section 7. Fault Diagnosis table 17.9.
1.8 Alarm contact line fault
CAUTION:
Only Pneumatech MGS line continuity monitor modules
should be fitted, otherwise the SYSTEM ALARM circuits
could provide spurious indications.
Integrity of the interconnecting wiring and input sensors
are constantly monitored by the SYSTEM ALARM detec-
tion circuits. The monitoring circuit is designed to detect
an open or short circuit as well as normal operation of
the pressure sensor. In the event of a line fault the NOR-
MAL LED remains illuminated, the appropriate gas ser-
vice alarm indicator and SYSTEM ALARM indicator will
illuminate and the audible warning sounds. When a line
continuity fault is detected the flash rate of the affected
circuit LED speeds up to show short circuit or slows to
show open circuit when the TEST switch is operated. This
facility is designed to aid fault diagnosis. Inputs must be
‘normally closed’ volt free contacts.
CAUTION:
As the alarm panel monitors specific resistance values,
only one input sensor (for each specific gas service) may
be connected to an alarm panel. Similarly it is not possible
to connect more than one alarm panel to a single input
sensor.
1.9 Remote audible warning devices
Remote audible warning devices may be fitted in locations
where warnings are necessary and alarm panels are not
fitted. Remote audible warning devices are housed in a
surface mounted enclosure containing a warning buzzer.
The audible warning device is connected by input cable to
the power supply PCB within the alarm panel (alarm ter-
minals AUD+ and AUD-, see figure 1.5). When the alarm
panel audible sounds the remote audible also sounds. A
maximum of four remote audible warning devices can be
fitted to an alarm panel and the cable length should not
exceed 50 metres.
1.10 Zeus 15 Relay interface panel
A dedicated relay interface panel assembly enables the
Zeus 15 medical gas central alarm system to be intercon-
nected to an event recording circuit of a building manage-
ment system, or other suitable alarm system. The relay
interface unit is housed within a standard alarm panel en-
closure and provides a fascia display of both POWER ON
and SYSTEM ALARM. The relay interface panel incorpo-
rates a dedicated power supply PCB and a dedicated re-
lay printed circuit board. The power supply PCB provides
no-volt terminals (C, 1, 2, 3, 4) for each channel CH1 to
CH5 to interconnect with a BMS system. The relay printed
circuit board is similar to the standard light display board,
except that the gas service alarm LED’s are replaced by
normally open low voltage relays. With the gas service op-
erating normally, relay contacts are closed providing con-
tinuity between terminals C and 1, 2, 3, 4. In the event of
a gas service failure the respective relay contacts open to
break the continuity between terminals C and either 1, 2,
3 or 4. Relays are connected to the BMS system at termi-
nals C, 1, 2, 3 and 4 and are rated at a maximum voltage
of 50V d.c. with a maximum current of 50mA.
For more details see document number 2005202 - Zeus
15 Relay Interface MK2 manual.
1.11 Operation of the alarm system
Each Zeus 15 medical gas alarm panel is connected to
the mains electrical power supply and operates by 15V
and 5V d.c. circuits from it’s integral transformer. Service
fault condition sensors provide the input to initiate both the
visual displays and audible warning. Programming of the
panels is done via switches which can be easily adjusted
on site from within the panel (see programming section
1.12).
