ELT
- Emergency Light Testing System
(image to follow)
| overview | control
panel | remote unit | mains
interface |
Introduction
The
Automatic
Emergency
Light
Test
System
has
been
designed
to
reduce
the
amount
of
man
hours
required
to
carry
out
the
mandatory
testing
of
emergency
lights
in
public
buildings.
BS5266,
the
regulation
covering
the
procedures
requires
that:
a)
maintained
unit
lamps
are
checked
daily
b)
all
units
are
tested
for
functionality
every
month
c)
partial
discharge
tests
are
carried
out
every
six
months
d)
full
discharge
tests
are
carried
out
on
all
units
after
three
years
and
annually
thereafter.
Carrying
out
these
tests,
although
essential,
is
laborious
and
time
consuming.
The
Automatic
Emergency
Light
Testing
System
will
do
all
these
tests
automatically,
reporting
any
problems
automatically
and
logging
all
test
results.
Return
to
top
of
page
System Overview
The system consists of a main control panel plus one
remote unit per luminaire. The remote units report back to the
main panel using the
mains wiring in the premises so no extra wiring is required.
The main panel can control up to 500 luminaires and each remote unit
can be configured to be maintained or non-maintained, three hour
or one hour type and the frequency of tests can also be set. In addition,
restrictions on when testing may be carried out can be imposed with
regard to a user specified time window, an input from a twilight
sensor
or an input from an alarm panel (so that luminaires will be tested
when the alarm is set and the premises empty).
All activities are logged at the main panel and can be printed on
the system printer either continuously or on user request. Thus a hard
copy of when each unit was tested is always available together with
log entries when either user or engineer modes are used.
The
log
has
a
1000
entry
capability
and
is
battery
backed.
The
system
information
(set-up
details
for
both
the
overall
system
and
for
individual
remote
units)
is
stored
in
EEPROM
which
which
is
therefore
preserved
even
if
the
battery
fails.
An additional serial port is available which could be
connected via a modem to a central station. Software for this port
is available on
request.
Return
to
top
of
page
Central Control Panel
The main control panel is housed in a painted
steel case which contains the main controller circuit board with
the printer module and the local
mains interface board. the front panel is hinged and the main pcb
with the two line by sixteen character LCD display is fitted to it
together
with the 16 character keypad.
The main control board provides all the 'engineering' and 'user'
mode facilities to set the time and date, change passwords, add or
delete
remote units and various other system related functions on the remote
units.
The mains interface board takes the bi-directional data from the main
board and transmits it into the mains wiring - it has no intelligence
on-board being purely a mains modem.
The printer module uses a plain dot matrix impact printer plus associated
controller board. It can easily be removed from the front panel for
ribbon replacement etc.
The real-time clock and the RAM (in which the log is maintained) are
battery backed in case of mains failure, whilst the system configuration
details are copied into non-volitile EEPROM which will survive even
if the on-board battery fails.
Return
to
top
of
page
Remote Unit
The
remote
unit
is
housed
in
a
small
painted
steel
case
and
contains
one
pcb
on
which
all
components
are
mounted.
Connections
are
made
from
the
incoming
mains
and
to
the
luminaire
to
be
controlled
and
additional
wiring
carries
the
signals
sensors
in
the
luminaire
for
charge
indicator
and
light
level.
The
light
level
sensor
is
a
light
dependant
resistor
fitted
into
a
'Terry'
clip
which
is
clipped
around
the
fluorescent
tube
in
the
luminaire.
The
charge
indicator
sensor
is
another
light
dependant
resistor
which
is
optically
coupled
to
the
luminaires
charge
indicator
LED
by
fitting
both
into
a
a
heat-shrink
or
rubber
sleeve.
As
communications
are
carried
out
via
mains
wiring
no
other
data
wiring
is
required
between
the
remote
units
and
the
control
panel.
Return
to
top
of
page
Mains Interface Unit
If
required
up
to
two
additional
mains
interface
units
may
be
connected
to
the
main
control
unit
(using
two-pair
cable)
so
that
a
separate
mains
unit
may
be
incorporated
into
the
system.
examples
of
such
additional
systems
are
a
computer
room
containing
luminaires
that
are
powered
using
a
UPS
(uninterruptible
power
supply)
where
the
neutral-earth
loop
is
broken
by
the
UPS
equipment,
or
a
remote
building
whose
mains
is
supplied
from
a
different
main
distribution
transformer,
which
again
would
break
the
neutral-earth
loop.
The two-pair cable for this link may be extended up to 1 kilometre.
Return
to
top
of
page
