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Instrument power supply
•
The power supply to the electronic equipment on the
switchboards must always come directly from an
isolation device with a fuse for the instrument part.
•
The electronic instruments and electromechanical
power devices such as relays, contactors, solenoid
valves, etc., must always be powered by separate
lines.
•
When the electronic instrument power supply is
strongly disturbed by voltage problems from power
units or motors, an isolation transformer should be
used for the controllers only, earthing the screen.
•
It is essential that the plant has a good earth
connection:
- the voltage between neutral and earth must not be >1V
- the resistance must be < 6Ω;
•
If the mains voltage fluctuates strongly, use a voltage
stabilizer.
•
In the proximity of high frequency generators or arc
welders, use adequate mains filters.
•
The power supply lines must be separate from the
instrument input and output ones.
Prescription UL
- Operating surrounding air temperature rating of 50°C
- For use on a flat surface of a type 1 enclosure
80543B_MHW_GF_VEDO-TL_0109_ENG
Inputs and outputs connection
•
To connect the analogue inputs, strain gauge,
linear, (TC, RTD) the following is necessary:
- physically separate the input cables from those of the
power supply, the outputs and the power connections.
- use woven and screened cables, with the screen
earthed in one point only.
•
To connect the control outputs, alarm (contactors,
solenoid valves, motors, fans, etc.), fit RC groups
(resistance and condensers in series) in parallel to
the inductive loads that operate in Alternating
Current.
(Note: all the condensers must conform to VDE
(class X2) standards and withstand a voltage of at
least 220V AC. The resistances must be at least 2W).
•
Fit a 1N4007 diode in parallel with the coil of the
inductive loads that operate in Direct Current.
GEFRAN S.p.A. declines all responsibility for
any damage to persons or property caused
by tampering, neglect, improper use or any
use which does not conform to the characte-
ristics of the controller and to the indica-
tions given in these Instructions for Use.
5
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