Installation 17
Power supply for DC powered models
The 24V DC supply, typically a stabilised power supply, is connected to the contacts - (2)
and + (1). The - (2) terminal should normally be connected to earth. The EMI earth ( )
must be connected to the earth rail or similar to protect against disturbances. Each process
connection has active transient protection, which is led to the EMI earth ( ).
AI Process Connections
The connection of two passive sensors like PT1000 and an active 2-wire transmitter are
shown. Note that low level sensors are returned to the AGnd, high quality ground.
This type of input is mainly intended for use with sensors using voltage outputs and
resistance elements for measuring temperature.
Voltage signals must be connected between the input and Agnd.
A cable screen is recommended and connects to the groundbar if any.
External transmitters for 4-20 mA can be powered from a +C output. A fast fuse should
be fitted in serial with the transmitter to protect the input from short circuits in the
transmitter.
All AGnds are internally linked to each other and to G0.
To attain maximum accuracy and to specifications, each respective AGnd should be used as
a reference for the measuring.
AO Process Connections
The AO terminals carry 0-10 V with reference to the AGnd terminal
(= Internal Signal Ground). The outputs are internally powered. The figure shows the
connection of a 24V AC powered control valve actuator, which is referenced to G0, and an
example with a simple voltmeter which is referenced to AGnd.
This type of output is mainly intended for use with damper motors, shunt valves,
frequency inverters and other analog actuators for 0–10 V.
Each output is current limited and short circuit proof.
Normal, high-ohm loads are connected between the output and AGnd. Other types of
loads for special applications with low-ohm loads are best connected between the output
and G0. See example with the Actuator that is connected to G0.
All AGnds are internally linked to each other and to G0 terminal.
Triac DO
The example shows actuators, AC relays and similar connected to GDO in one end. In the
other end, the triac output of the EXOcompact sources, when active, GO to the load.
Mosfet DO
The example shows actuators, DC relays and similar connected to GDO in one end. In the
other end, the mosfet output of the EXOcompact sources, when active, - to the load.
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