Safe Area
Hazardous Area
-
IS-L101L
Beacon
+
0V
+
Power
Supply
Diode Return
Barrier
Barrier
On/Off
28V 1.2W
Positive
Ac.Sw
Fig 4 Single stage alarm using two channel barrier.
The circuit will continue to work at lower voltages, but the
beacon brilliance will be reduced.
6.2 Use with a IS-A105N intrinsically safe sounder
When using the IS-L101L beacon with an IS-A105N
sounder, the Special Conditions for Safe Use in the
sounder certificate, Sira 04ATEX2301X must also be met.
The very low current consumption of the IS-L101L beacon
allows it and a IS-A105N intrinsically safe sounder to be
powered from a common Zener barrier as shown in Fig 5.
This reduces the sounder output by about 2dB.
The IS-L101L beacon contains a circuit that will silence the
sounder for a pre-set time, but leave the beacon flashing at
twice its normal frequency. The sounder silence time is set by
internal DIP switches. An operator may therefore silence the
audible alarm but be continuously reminded of the alarm
condition by the beacon. If the alarm is not cleared within the
silence time, the sounder will be reactivated. If the alarm is
cleared during the silence time the beacon will stop flashing,
but the beacon and the sounder will both be re-activated if
the alarm reoccurs. See table 1 on page 5 of these
instructions for full DIP switch settings.
Note when the beacon is operated on its own, without a
sounder connected, all of the DIP switches should be set
to OFF the position.
Safe Area
Hazardous Area
IS-A105N
Sounder
Accept
Switch
+
S+
S-
-
IS-L101L
Beacon
28V 93mA (see sounder certificate)
Positive
0V
+
Power
Supply
Barrier
On/Off
Fig 5 Combined beacon and sounder with alarm accept
switch
The silence accept push-button may be any mechanically
operated switch, providing it has an IP protection suitable for
the environmental conditions to which it is subjected, located
within the same hazardous area as the beacon, see section
4.5.
In order that the beacon continues to produce a reasonable
light output level when used in conjunction with an IS-A105N
sounder, the power supply voltage to the barrier should be
maintained at a minimum of 18V.
7. ELECTRICAL SYSTEM DESIGN FOR INSTALLATION IN
HAZARDOUS AREAS USING GALVANIC ISOLATORS.
Although more expensive than Zener barriers, galvanic
isolators are easier to install as they do not require a high
integrity earth connection. Any certified device with output
safety parameters below the maximum input safety
parameters of the IS-L101L beacon may be used – See
section 4.3.
7.1 Stand alone operation
Fig 6 shows the basic circuit that is used for all stand alone
applications.
Safe Area
Hazardous Area
+
Ac.Sw
-
IS-L101L
Beacon
+
-
On / Off
Galvanic 28V 1.2W
Isolator
+
0V
Power
Supply
Fig 6 Basic circuit for use with a galvanic isolator.
The control arrangement will vary depending upon the
isolator chosen. The galvanic isolator must be able to supply
an output of 30mA at about 16V. This circuit may also be
used if the beacon is controlled by a mechanically activated
switch on the hazardous area side of the isolator.
7.2 Use with a IS-A105N intrinsically safe sounder
When using the IS-L101L beacon with a IS-A105N
sounder, the Special Conditions for Safe Use in the
sounder certificate, Sira 04ATEX2301X must also be met.
The very low current consumption of the IS-L101L beacon
allows it and a IS-A105N intrinsically safe sounder to be
powered from a common galvanic isolator as shown in Fig 7.
This reduces the sounder output by about 2dBA.
Safe Area
Hazardous Area
IS-A105N
Sounder
Accept
Switch
+
S+
S-
-
IS-L101L
Beacon
Galvanic 28V 93mA (see sounder certificate)
Isolator
0V
+
Power
Supply
+
-
On / Off
Fig 7 Combined beacon and sounder with alarm accept
switch
The IS-L101L beacon contains a circuit that will silence the
sounder for a pre-set time, but leave the beacon flashing at
twice its normal frequency. The sounder silence time is set by
internal DIP switches. An operator may therefore silence the
NOTE:
If sounder silence is not required, cut the
link across the Ac.Sw connector.
NOTE
If sounder silence is not required, cut the
link across the Ac.Sw connector.
