Siemens SINUMERIK 840D Description Of Functions page 40

2 Configuring
2.3 Configuring the hydraulic drive
!
Example
2-40
SINUMERIK 840D/SIMODRIVE 611 digital Descr. of Functions HLA Module (FBHLA) – 04.00 Edition
The shutoff valves are automatically enabled and disabled in the correct switch-
ing sequence by the HLA module.
Start precondition: The hydraulic pressure must be available before
the system is switched on.
Warning
In the event of sudden failure (e.g. open circuit) of the external 24 V supply, an
axial storage capacitor on the HLA module provides energy to supply the servo
solenoid valve until such time as the pressure supply for a configured shutoff
valve is disabled.
The machine manufacturer must verify the interaction between valves, making
allowance for all tolerances in the controlled system.
The energy content of the storage capacitors is dependent upon
S
the tolerances of the capacitors,
S
the voltage level of the external supply and
S
the charging time of the integrated capacitors (instant of voltage failure).
The available reaction time is mainly defined by
S
the power required for the current machining step,
S
the response time of the shutoff valves and
S
the trip threshold of the servo solenoid valves.
A B
P T
a
P
Fig. 2-15 Example of a shutoff valve application
b
S U
T B A
 Siemens AG 2000. All rights reserved
02.99
Servo solenoid
valve
Shutoff valve