How to install a Sx2WEB system
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1.9.2 How to wire the power supply
The DIN-rail modules powered by to 24 Vdc nominal (15-30 Vdc) come with in/out connections to speed
up wiring: there are two A1(+) terminals that are internally short circuited, and two A2(-) terminals that
are also short circuited.
The best wiring should be carried out as shown below. The immunity to EMC can be improved
connecting the minus of the DC power supplier of the system (-) to the earth ground.
All the DIN-rail modules with the in/out terminals come with two short wires already screwed into the A1
and A2 terminals in order to speed up commissioning.
Recommendations:
1) Use a battery back-up system to avoid switching off the installation if a power down should
occur.
2) Be careful to have a total current not greater than 3A on the power supply if using the in/out
terminals, since the maximum current that the internal connections can withstand is 3A.
If Dc motors are used to control roller blinds or windows, do not supply them from the same
wires used in the in/out connections since the maximum current they can withstand is 3A (see
below: in this case the sizing of the power supply must take into consideration also the
consumption of the motor).
3) It is recommended that the system is supplied @24Vdc in order to reduce the current and thus
the stress on the internal electronic components. This will result in a longer lifetime of the
modules.
