Calculating The Total Pfh Value Of A Safety Zone - Bosch rexroth ctrlX SAFETY SafeMotion Applications Manual

The following conditions/restrictions apply to the general use of the formula for
PFH calculation for an axis:
Table 7: Variable description to calculate PFH for an axis
Variable Value
PFH Refer to
M5 option
technology module "M5"
PFH Refer to
EC option
technology module "M5"
PFH See manufacturer's specifica-
1)
encoder
tion (when using Rexroth
motors, see
Required motors and meas-
uring systems on page
PFH Refer to
SBC function, brake 1
technology module "M5"
PFH See manufacturer's specifica-
31)
Brake 1
tion (when using Rexroth
motors, see
Required motors and meas-
uring systems on page
Legend:
PFH=(1-DC)/MTTFD
1):
CCF factor: 1%
2):
PFH=λ
3):
D
6.4.4

Calculating the total PFH value of a safety zone

To determine the required total PFH value of an axis or a safety zone, the
PFH values of the individual axes and of the required third-party components
have to be used for calculation. The figure below illustrates all the components
relevant to the calculation:
Fig. 4: SafeMotion: Determining the PFH for a safety zone
Third-party component
1)
Not yet possible
2)
To calculate the PFH value of a safety zone, a valid PFH value has to be available
for all components which have an influence on the safety function (if necessary,
procure the PFH value from the component manufacturer).
Table 8: SafeMotion: Formula to calculate PFH for a safety zone
PFH = PFH
Safety zone Discrete_selection
The following conditions/restrictions apply to the general use of the formula for
PFH calculation for a safety zone:
R911404905, Edition 02
Safety characteristics of the safety system
Description
⮫ Optional safety This value is independent of the safety functions
used and thereby independent of the safety level
to be attained.
⮫ Optional safety Enter "1" for this variable, if an EnDat–2.2
encoder is configured, see
motors and measuring systems on page 166
Use the value of the encoder connected to XG20
or XG21, if safety functions requiring an encoder
⮫ Chapter are used. Otherwise, enter "0" for this variable.
166)
⮫ Optional safety Enter "0" for this variable if the safety function
"SBC" is not used for brake 1.
Use the value of the connected brake, if the
safety function "SBC" is used.
⮫ Chapter
If the safety function "SBC" is not used, enter "0"
for this variable.
166)
+ PFH + PFH
Axis_1 Axis_2
ctrlX SAFETY "SafeMotion"
+...+ PFH
Axis_n
31 / 302
⮫ Chapter Required
Bosch Rexroth AG