Before You Begin
Menvier40/100
Page 8
Power Availability
Before connecting any external devices to
the control unit, you must make sure that
the control unit can provide sufficient
current to power the system during a mains
failure for the time required to meet the
appropriate standard. PD6662 Grade 3
requires 12 hours (when the control unit is
fitted with an ATS4 communicator)
including two periods of 15 mins in alarm.
The amount of current available from the
control unit depends on the size of battery
fitted and its health. The current taken by
the control unit PCB, communicator and
keypads is given in
Technical Specifications
– EN50131-6 Ratings
on page 31.
The following calculation shows a simplified
example: in an alarm system with an i-
Menvier40 control unit, two i-kp01 keypads,
and 20 wired PIRs the system takes the
following total quiescent current:
Device
Current
Control unit PCB
120mA
20 x PIRs at 15mA each
300mA
1 x (wired expander)
20mA
2 x i-kp01 at 30mA each
(backlights off)
60mA
Siren (quiescent)
25mA
Total
525mA
During an alarm, these figures become:
Device
Current
Control unit PCB
200mA
20 x PIRs at 15mA each
300mA
1 x (wired expander)
20mA
2 x i-kp01 at 60mA each
(backlights off)
120mA
Siren (in alarm)
400mA
Total
1040mA
The total amp hours required =
(0.525 A x 11.5h) + (1.040A x 0.5h) =
6.56Ah
Note that for Grade 3 this example
assumes that the communicator has its own
power supply.
One new, fully charged, 7Ah battery can
provide the charge required by the example
system and would meet the PD6662 Grade
3 requirements.
Note: All current drawn from the Aux
terminals must be included in the overall
calculation.
CAUTION: Ensure that the system does not
demand more than the maximum current
available from the control unit during an
alarm, see page 31.
Bus Cabling
Requirements
Cable Type
In general, the control unit requires
standard 7/0.2 un-screened four core alarm
cable for wiring the bus.
For maximum performance in harsh
environments use twisted pair cable with a
characteristic impedance of 100-120ohms
eg: CAT5 or cable designed for RS485.
Use one pair for data lines A and B. Use the
other pair for 12V and 0V. For optimum
performance the voltage at the keypads
and expanders should be greater than 12V.
Screened cable may prove necessary if the
installation site has equipment that
produces high levels of R.F. (Radio
Frequencies). For example, welding
equipment is known to produce a large
amount of radio interference. If screened
cable is required, you should keep to the
following guidelines:
1. Avoid earth loops by connecting the
screen on the cable to mains earth at
the control unit but not at the keypad or
expander.
2. The continuity of the cable screen is
most important and screens MUST be
continuous along the full length of the
cable.
3. Where the cable enters any metal
enclosure, ensure the screen is isolated
from the case.
Cable Segregation
Segregate the bus cabling from any other
wiring, such as mains supply cables,
telephone cables, computer network cables
and R.F. cables. Use cable ties to keep
cables separated.
Keep the bus cable clear of cables supplying
sounders, extension loudspeakers or any
other high current devices.
Cable Configuration and Length
You can connect up to 20 devices to the
control unit bus on a Menvier40, or 45 on a
Menvier100. You may connect the devices
either in daisy chain (serially), or in star