Printed in USA 150313
Page 08
5.3 Option Relay Output
The two relays are activated in dependence of the gas concentration. If the gas concentration exceeds the
adjusted alarm threshold, the corresponding relay switches on. If the gas concentration falls below the
threshold minus hysteresis, the relay switches off again.
The contact function for relay 2, NC (normally closed) or NO (normally open), can be selected via the jumper
NO/NC. See fig 1 and 3. Relay 1 is equipped with a change-over contact.
Via the MODBus interface the two alarm thresholds and the hysteresis are freely adjustable at the PC within
the measuring range. The procedure can be read from the user manual “MODBus Software”.
The following parameters are factory-set.
Alarm threshold 1 = Relay 1: 10 % LEL
Alarm threshold 2 = Relay 2: 20 % LEL
Switching hysteresis: 5 % LEL
Specifications subject to change without notice. | USA 151203 | Page 8 of 14
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AT-3300_V3 – UserManual
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