User guide

Wiring T82
14
5.2 Connecting the sensor cables
Terminal assignment of the sensor terminals (® å 5, ä 13).
NOTICE
When connecting 2 sensors, ensure that there is no galvanic connection between the
sensors (e.g. caused by sensor elements that are not isolated from the thermowell). The
resulting equalizing currents distort the measurement considerably.
The sensors must remain galvanically isolated from one another by connecting each sensor
separately to a transmitter. The transmitter provides sufficient galvanic isolation (> 2 kV AC)
between the input and output.
The following connection combinations are possible when both sensor inputs are assigned:
Sensor input 1
Sensor input 2
RTD or
resistance
transmitter,
two-wire
RTD or
resistance
transmitter,
three-wire
RTD or
resistance
transmitter,
four-wire
Thermocouple
(TC), voltage
transmitter
RTD or resistance
transmitter, two-wire
4 4 - 4
RTD or resistance
transmitter, three-wire
4 4 - 4
RTD or resistance
transmitter, four-wire
- - - -
Thermocouple (TC),
voltage transmitter
4 4 4 4
5.3 Connecting the power supply and signal cables
!
CAUTION
Switch off power supply before installing or connecting the head transmitter. Failure to
observe this may result in destruction of parts of the electronics.
Cable specification
• A normal device cable suffices if only the analog signal is used.
• A shielded cable is recommended for HART
®
communication. Take the plant grounding
concept into consideration.
Please also observe the general procedure on (® ä 13).