Calculating The Pfh Component Of An Axis - Bosch rexroth ctrlX SAFETY SafeMotion Applications Manual

ctrlX SAFETY "SafeMotion"
30 / 302
Safety characteristics of the safety system
Depending on the axis safety functions used and the device range used, there
are the following safety characteristics:
Designation
PFH
2)
PFH
PFH
Mission Time
MTTF
DC
Legend:
1):
ture of 40 °C (see also Ambient and operating conditions in the Project Plan-
ning Manuals).
2):
account (e.g., encoder, brake, safety control). For determining the actual PFH
value, see
"Mission Time" and "Proof Test" interval
−
−
−
−
6.4.3

Calculating the PFH component of an axis

To determine the required total PFH value of an axis, the PFH values of the
individual components relevant to the safety function 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. 3: SafeMotion: Determining the PFH for an axis
1)
To calculate the PFH value of an axis, 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 6: SafeMotion: Formula to calculate PFH for an axis
PFH
Bosch Rexroth AG
M5 option (no SBC function) 1),
SBC function, brake 1 1), 2)
/ PFH
EnDat 1), 2)
EC option
d/channel 1)
avg
The specified safety characteristics refer to an average ambient tempera-
PFH value of an axis with SafeMotion, additional components not taken into
⮫ Calculating the PFH component of an axis
The "Mission Time" of all components used has to be observed and com-
plied with. After the "Mission Time" of a component has elapsed, the com-
ponent has to be discarded or replaced. It is not allowed to continue oper-
ating the component!
The drive system ctrlX DRIVE does not monitor or log the "Mission Time".
After the component was discarded ("Mission Time" has elapsed), it has to
be ensured that the component cannot be reused (e.g., by disabling it).
If a component (with valid "Mission Time") is decommissioned, the "Mis-
sion Time" has to be recorded and continued when the component is com-
missioned again.
The "Proof Test" has not been specified for ctrlX DRIVEplus. Therefore, the
"Mission Time" cannot be reset by a "Proof Test".
Third-party component
= PFH + PFH
axis M5 option
ctrlX DRIVEplus
1×10
1×10
2×10
175,200 h (20 years)
> 90 years
> 95 %
+ PFH + PFH
EC option encoder
1/h
-9
1/h
-9
1/h
-9
.
+ PFH
SBC function, brake 1 brake 1
R911404905, Edition 02