Safety Positions - Burkert 8681 Operating Instructions Manual

Control Head Type 8681
Maintenance,troubleshooting
19.2.

Safety positions

Safety positions after failure of the electrical or pneumatic auxiliary power:
Operating mode
up
down
up
down
up
down
By default the control head is equipped with solenoid valves which operate in NC mode,
the design for double-acting actuators is equipped with 1 solenoid valve NC and 1 solenoid valve NO**.
If process valves with several switching positions (e.g. double-seated valves) are connected, the safety positions
of the individual actuators can be viewed according to the same logic as for a classical single-seated valve.
Safety positions after failure of the bus communication:
AS interface:
If the Watchdog is activated (default), behavior is the same as a failure of the auxiliary electrical power, i.e. all
solenoid valve outputs are set to "0".
DeviceNet:
See Chapter "12.12.1. Configuration of the safety position of solenoid valves during a bus error".
* NC: 3/2-way valve; closed in rest position, output A unloaded,
** NO: 3/2-way valve; opened in rest position, output A pressurized.
Process valve
design
single-acting
Control function A
• air opening
• spring closing
single-acting
Control function B
• air closing
• spring opening
double-acting
Control function I
• air opening
• air closing
Safety positions
after failure of the auxiliary power
electrical
down
up
not defined for
both solenoid valves
NC*, but
_____________________
defined for
Solenoid valve1 NC* +
Solenoid valve2 NO**
English
pneumatic
down
up
not defined
3
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