Dräger REGARD 3900 Serie Instrucciones De Uso página 52

Components
4.2.2 Contrast settings
To adjust the contrast, turn the control using a suitable screwdriver. The LCD
screens are temperature-sensitive and therefore adjustment is necessary in very
cold or very hot environments.
4.3 Input module
An input module has four channels; each of which allow the current signal from a
remote sensor transmitter to be monitored. For each channel, alarms for up to three
gas values (A1, A2 and A3) and two fault conditions (F1 and F2) are available.
Potentially dangerous or noxious gas values can be displayed on the transmitter by
setting alarm thresholds for the gas values. Depending on the configuration, the
alarms are activated when the monitored gas values increase or decrease. The
faults (F1 and F2) are triggered when the transmitter emits the corresponding fault
signal (F2 is only used if the transmitter emits a second fault signal).
Each input module has three relays, which are activated as soon as an F1 (Fault 1),
A1 (pre-alarm) and A2 (main alarm) signal is received from one of the channels
monitored by the PCB. The relay is a zero potential, single pole changeover relay
which can be used to activate external warning devices. The backup on the input
module protects the module against short circuits to the input channels (Ch1 to
Ch4).
®
REGARD 3900