Burkert 8681, Operating Instructions Manual, Page: 57 / 166

57
AS Interface - Design
NOTE!
If all 3 solenoid valves are simultaneously controlled via the AS interface, the electronics will activate the
valves sequentially with a 200 ms time delay to protect the bus from overloads.
External power supply for solenoid valves:
External power supply: 19.2 V DC to 31.6 V DC
The power supply unit must include a secure disconnect in
accordance with IEC 60364-4-41. It must conform to the SELV
standard. The ground potential must not have a ground connection.
Power consumption from external
power supply for outputs
(solenoid valves) - without integrated
current limiting: <110 mA at 24 V DC (for 200 ms after switching on of the 3.
rd
valve)
Power consumption from AS-i
for inputs and display: <150 mA (incl. external initiator, feedback and fault display)
Integrated short-circuit protection
Please consider the following information to power requirement and to the maximum expansion
stage of the AS interface network in chapter “12.3 Number of connectable control heads” and in the
AS interface specifications, where applicable.
12.6 Design aid
Design aid for supply of the valves via the AS-i bus
Power consumption of the electronics:
P
El
= 1.0 W or I
El
= 33 mA at 30.5 V
Power consumption of a valve during activation (200 ms):
P
Valve-ON
= 0.9 W or
I
Valve-ON
= 30 mA at 30.5 V
Power consumption of a valve after reduction:
P
Valve
= 0.6 W or I
Valve
= 20 mA at 30.5 V
Power consumption of an optical position report:
P
LED
= 1.0 W or I
LED
= 33 mA at 30.5 V
For the design of the maximum line lengths observe chapter “12.4 Maximum length of the bus line” .
Even if several control head valves are switched simultaneously via the bus, the switching signal is
passed on to the valves in staggered order, i.e. only one valve is ever taken up 0.9 W.
english
Control Head Type 8681