Bosch Rexroth 4WRLE 4 Series, Operating Instructions Manual

Page: 16 / 44

16/44 Safety instructions
Bosch Rexroth AG , 4WRPEH6_3X, 4WRPEH10_3X, 4WRPE6_3X, 4WRPE10_3X, 4WRLE_4X; RE 29118-B/09.2021
2.7.2 Limits of the safety-related parts
Assessment of the valve with IO-Link interface according to ISO 13849-2:
• Potential failures or unidentified error states of the valve with IO-Link interface
always require application-dependent and suitable system-related measures
according to EN 13849-1 (see chapter 2.7.1).
• When using the valve with IO-Link interface in compliance with categories
2 or 3 according to EN13849-1, adequate cyclic diagnosis or monitoring of the
valve function outside of the valve by the control system must be implemented
by the machine integrator. Without suitable diagnostic measures, only cat.
B or 1 according to EN13849-1 can be reached.
2.7.3 Residual risks/error states
The following residual risks or error states may occur and must be taken into
account by appropriate system-related measures:
• Complete failure of the electronics of the valve
• Faulty output of operating states
• Uncontrolled movement of the valve control spool (may lead to uncontrolled
movement of the cylinder)
• Fuse protection in the case of short-circuits in the electronics of the valve with
IO-Link interface by means of appropriate protection and design of the supply line
(fuse protection against currents >4 A).
2.7.4 MTTF
d
, DC, CCF
For valves with IO-Link interface, MTFF
d
valves can be calculated according to the
information specified in the table using the following formula:
Table 6: Information for calculation of the MTTF
d
value
1
1 1 1
dGesamt
dHydraulikteil dAbschaltpfad dNetzteil
MTTF
MTTF MTTF MTTF

 
MTTF
d
values
Type of
actuation Valve type Hydraulic
components Switch-off path SELV/PELV power supply
unit + safe IO-Link terminal MTTF
d
value
Valve and
electronics
switch-off path
(without
additional
components)
Example of total
MTTF
d
value
(for power supply
unit + IO-Link
terminal with MTTF
d
value of 1 mio. h)
Direct actuated
valves 4WRPEH10
4WRPEH6
4WRPE6
4WRPE10
150 years 1000 years
MTTF
d
value depending
on manufacturer of power
supply unit + safe IO-Link
terminal
(MTTF
d
= approx. 2 x MTBF)
e.g. MTBF = 500000 h
→ MTTF
d
value =
approx. 1 mio. h (114 years)
130 years 60
Pilot-operated
valves 4WRLE 75 years 1000 years 69 years 43