Dräger REGARD 3900 Serie Instrucciones De Uso página 59

5.5.2 DC supply voltage
To supply the control unit via an external DC power supply:
– Use a regulated, fault-free 24 V DC power supply.
– If it is likely that the supply will be exposed to high levels of conducted RF
interference, use a filter to eliminate the interference.
– If the HART
used with the remote sensor transmitters, the supply must comply with the
HART
transmitter).
5.5.3 AC and DC power supply
If both options are used, the AC voltage supply is the primary supply and the DC
voltage supply is the supporting supply. Diodes and/or relays may be required in
order to switch from the primary to the supporting power supply (see diode circuit).
REGARD
®
diagnostics (Highway Addressable Remote Transducer) can be
®
requirements (see the instructions for use for the remote sensor
®
3900
Installation & commissioning