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Instrument power supply
Installation category II and pollution degree 2.
• 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 lines.
Prescription UL
- Operating surrounding air temperature rating of 50°C
- For use on a flat surface of a type 1 enclosure
6
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 connec-
tions.
- 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 characteristics of the controller
and to the indications given in these
Instructions for Use.
80954E_MHW_GF_LOOPER_01-2012_ENG
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