gefran GF VEDO HL

5
80546B_MHW_GF_VEDO-HL_02-2013_ENG
Instrument power supply
• The power supply to the electronic equipment on the
switchboards must always come directly from an isola-
tion device with a fuse for the instrument part.
• The electronic instruments and electromechanical
power devices such as relays, contactors, solenoid val-
ves, etc., must always be powered by separate lines.
• When the electronic instrument power supply is stron-
gly 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.
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 ear-
thed in one point only.
• To connect the control outputs, alarm ( c o n t a c t o r s ,
solenoid valves, motors, fans, etc.), fit RC groups (resi-
stance and condensers in series) in parallel to the induc-
tive 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 induc-
tive 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.