ROTRONIC HF3 - Manual (Page 15)

E-M-HF3-V1_22
Rotronic AG
Bassersdorf, Switzerland
Document code Unit
HygroFlex HF3 Transmitters and Thermo-
hygrostats: User Guide Instruction Manual
Document Type
Page 15 of 27
Document title
© 2009-2011; Rotronic AG E-M-HF3-V1_22
6.3.2 HF33: 3-wire transmitter
Electrical diagram for voltage outputs
The maximum permissible cable length can be
determined under consideration of the voltage
drop caused by the current flowing to the devices
connected to the unit. The voltage drop in the
cable depends both on cable resistance and on
the equivalent resistance of the devices
connected in parallel to the unit. The total
resistance connected to each unit output should
be at least 1000 ohms. Cable resistance should
not be more than 1/1000 of the load resistance.
Minimum load requirements apply to the external device or circuit connected to the HF3 transmitter. These
requirements are defined in the “Operation” chapter
Electrical diagram for current outputs
The maximum permissible cable length,
connecting the unit to other devices, is
determined by the total resistance resulting from
the addition of the cable resistance and that of
the devices connected in series with the unit.
This resistance should not exceed 500 ohms.
Terminal block diagram for type D and W
Terminals Description
V+
Power supply: 15…40 VDC (+)
or 12…28 VAC (Phase)
GND Power supply (-) or neutral
OUT1
Relative humidity or dew point (+)
OUT-1
OUT2
Temperature output (+)
OUT-2
GND Ground (tied with other GND)