Under Range; Alarm, Fault And Activity Leds; Power And Inhibit Leds - Dräger REGARD 3900 Series Instructions For Use Manual

6.1.4

Under range

If the gas value falls under the measuring range (the transmitter signal drops below
3.8 mA - but this is not a maintenance or fault signal), Under-range is displayed.
6.1.5 Maintenance
If the transmitter needs to be serviced (the transmitter emits a maintenance signal),
Maintenance is displayed.
6.2

Alarm, fault and activity LEDs

The alarm thresholds and activation modes are adapted to the requirements of the
user. The actions and measures to be taken upon activation of an alarm or fault
LED must be specified by the person responsible for the gas detection system.
Although there are up to three gas alarms (A1 to A3) and two fault alarms (F1 and
F2), the control unit has no LEDs for alarm A3 and fault F2. External warning units
can be configured to display alarm A3 and fault F2.
LED
Alarm A1
Alarm A2
Fault F1
Active
6.3

Power and inhibit LEDs

The power supply to the control unit is made via an AC or DC power source, or
both. If both are used, the DC power source (usually a battery system) acts as an
emergency power supply if the AC power supply fails.
Power AC LED
If the control unit uses both AC and DC sources, the connection of this LED is
optional. If the LED is connected, it lights up when the control unit is supplied via
the (primary) AC power source. The LED is off when the control unit is supplied via
the (supporting) DC power source.
Power DC LED
The LED lights up when the internal modules are supplied with a 24 V DC power
supply. (Irrespective of the power supply to the control unit, the internal control
modules require a 24 V DC supply.)
Flashes
Lights up
Off
Flashes
Lights up
Off
Flashes
Lights up
Off
Flashes
Lights up
Off
®
REGARD 3900
Condition
A1 alarm triggered
A1 alarm acknowledged, however alarm state pres-
ent
No alarm state
A2 alarm triggered
A2 alarm acknowledged, however alarm state pres-
ent
No alarm state
F1 alarm triggered
F1 alarm acknowledged, however fault present
Channel fault-free
Channel active
Alarm lock
Channel inactive
Operation