Burkert Type 8791 - Manual (Page 26)

26
Fluid connection
for double-acting actuators (control function i):
→
Connect working connections A1 and A2 to the respective
chambers of the double-acting actuator.
Safety positions see chapter “9.3. Safety positions”.
important information for perfect control behaviour!
This ensures that the control behaviour is not extremely
negatively affected in the upper stroke range on account of
too little pressure difference.
• keep the applied supply pressure at least 0.5 – 1 bar
above the pressure which is required to move the pneu-
matic actuator to its end position.
If fluctuations are greater, the control parameters measured
with the
X.TUNE function are not optimum.
• during operation keep the fluctuations of the supply
pressure as low as possible (max. ±10%).
9.3. safety positions
The safety position after failure of the electrical auxiliary power
depends on the fluid connection of the actuator to the working con-
nections A1 or A2.
9.3.1. single-acting actuators
actuator system
safety positions after failure of the
electrical aux-
iliary power
pneumatic
auxiliary power
up
down
down
→
Connection
according to
“Fig. 17”
down
up
→
Connection
according to
“Fig. 18”
Control function A
up
down
up
→
Connection
according to
“Fig. 17”
up
down
→
Connection
according to
“Fig. 18”
Control function B
Tab. 10: Safety positions - single-acting actuators
english
Type 8791