Dräger Polytron 8000 Series Technical Manual page 65

Relay contact Normally Open (NO) and configuration Normally Energized
This is the Dräger standard setting for relay operation.
The alarm indicator is connected to the Normally Open relay contact. The relay is
energized during operation and connects the Common terminal with the Normally
Open contact. The electric circuit is closed and current flows to the alarm indicator.
If an alarm is triggered, the relay de-energizes
This setting is suitable for green status lights.
Failures such as field wiring faults, defective alarm indicators and power loss to the
transmitter are indicated.
Energized
coil +
coil -
Fig. 17
Relay contact Normally Open (NO) and configuration Energized on alarm
The alarm indicator is connected to the Normally Open relay contact. The relay is
de-energized during operation and connects the Common terminal with the
Normally Closed contact. The electric circuit is open and no current flows to the
alarm indicator.
If an alarm is triggered, the relay energizes and the alarm indicator is active.
This setting is suitable for horns or strobes.
Failures such as field wiring faults, defective alarm indicators or power loss to the
transmitter are not indicated.
De-energized
Fig. 18
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Technical Manual
Dräger Polytron
NC
NO
COM
Example for relay configuration Normally Energized and Normally Open
relay contact.
coil +
NC
NO
COM
coil -
Example for relay configuration Energized on alarm and Normally Open
relay contact.
®
8000 Series
Instrument settings
De-energized, alarm triggerd / power loss
coil +
NC
NO
COM
coil -
Energized, alarm triggerd
coil +
NC
NO
COM
coil -
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