Selection Of Shutoff Valves - Siemens SINAMICS S120 System Manual

3.3.3

Selection of shutoff valves

General
The shutoff valves are automatically enabled and disabled in the correct switching sequence
by the HLA module.
Start precondition
When using safety functions, only safe shutoff valves with at least 1 feedback signal are
permitted.
The hydraulic pressure must be available before the system is switched on.
In the event of sudden failure (e.g. broken cable) of the external 26.5 V supply, the energy
storage capacitor for each axis 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
switched off. Note the following boundary conditions when selecting the valves:
● The energy content of the storage capacitors is dependent on:
– The tolerances of the capacitors
– The voltage level of the external supply
– The charging time of the integrated capacitors (instant of voltage failure)
● The available response time is mainly defined by:
– The power required for the actual machining step
– The response time of the shutoff valves
– The shutdown voltage threshold of the servo solenoid valves
Danger to life when the external 26.5 V power supply fails
A failure of the external power supply when the energy content of the storage capacitors is
too low can cause the shutoff valves to remain open. This can lead to critical situations that
may result in death or serious injury.
• The machine manufacturer must verify the interaction between valves, making
Hydraulic Drive
System Manual, 04/2015, 6SL3097-4BA00-0BP1
WARNING
allowance for all tolerances in the controlled system.
Configuration
3.3 Configuring the hydraulics
43