Revision 1 – 04.12.2015 8/28
EXAMPLE OF CONNECTION TO SECURITY PRESSURE SWITCH
Alarm related to security pressure switch A21 is joined to the lacking phase to all the digital inputs.
This is a shut off alarm: below you can find the connection drawing both to contactors 24Vac and/or 230Vac.
Contactors 230Vac
If the operation of the contactors and
solenoid valves comes through 230 Vac, the
digital inputs have to be connected to 12
Vac; next to the contact of the pressure
switch, place and energize an auxiliary
relay and put the contact in serie to
12 Vac (L) (see drawing on the right).
When the pressure switch is closed, the
auxiliary relay with contact closed supply
power to the digital inputs; the power
supply of the controller is connected before
the contact of the relay.
When the pressure switch opens, the
auxiliary relay opens power to the digital
inputs; the controller detects all the digital
inputs open and signal the alarm “SEC.
PRESSURE SWITCH”.
Contactors 24Vac
If the operation of the contactors and
soenoid valves come through 24 Vac, the
digital inputs have to be connected to 24
Vac (see drawing on the right); on this
way when the pressure switch opens due
to high pressure, 24 Vac lacks and
deenergize all the contactors, solenoid
valve and digital: the controller detects
all the digital inputs opened and signal
the alarm “SEC. PRESSURE SWITCH”.
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