SFFS422 May   2022

 

  1.   Trademarks
  2.   2
  3. 1Scope
  4. 2Related Documents
  5. 3Related Standards and Acronyms
  6. 4Concept Overview
    1. 4.1 System Block Diagram
    2. 4.2 System Specifications
    3. 4.3 Conditions of use: Assumptions
      1. 4.3.1 Generic Assumptions
      2. 4.3.2 Specific Assumptions
    4. 4.4 Safe Torque Off Implementation
      1. 4.4.1 Subsystem Elements
      2. 4.4.2 STO Safe Subsystem States and Timing Diagram
      3. 4.4.3 STO_1 Subsystem
      4. 4.4.4 STO_2 Subsystem
      5. 4.4.5 MCU (SIL 1) Diagnostic Coverage
      6. 4.4.6 STO_FB Subsystem
      7. 4.4.7 Information on ICs
        1. 4.4.7.1 Isolated 24-V Input Receiver
        2. 4.4.7.2 Load Switch: TPS22919
        3. 4.4.7.3 High-Side Switch: TPS27S100
        4. 4.4.7.4 Isolated Gate Driver: ISO5852S (ISO5452)
    5. 4.5 Safe State
  7. 5Concept FMEA
    1. 5.1 System FMEA
  8. 6References

3 Related Standards and Acronyms

Table 3-1 Standards References
Standard Title
IEC 61800-5-2 Adjustable speed electrical power drive systems – Part 5-2: Safety requirements – Functional
IEC 61508 Functional safety of electrical/electronic/programmable electronic safety-related systems
ISO13849-1/2

Safety of machinery -- Safety-related parts of control systems

-- Part 1: General principles for design, --- Part 2: Validation
IEC 60204-1 Safety of machinery - Electrical equipment of machines - Part 1: General requirements
IEC 62061 Safety of machinery - Functional safety of safety-related electrical, electronic and programmable electronic control systems(1)
(1) Defines stop category 0, uncontrolled stop
Table 3-2 Acronyms
Acronym Description
DC Diagnostic coverage
FIT Failure in time (1-e9/hour)
HFT Hardware fault tolerance
MTTF Mean time to failure (per year)
MTTFd Mean time to failure – dangerous (per year)
PFD Probability of dangerous failure
PFH Average frequency of a dangerous failure of the safety function [per hour]
SFF Safe failure fraction
PDS/SR Power drive system, safety related
DFD Dangerous failure detected. Acronym used on the FMEA tables
DFU Dangerous failure not detected. Acronym used on the FMEA tables
SF Safe failure
NEF No effect failures, failures which don’t have an impact on the safety function. Acronym used in FMEA tables.
FRT Fault response time
DTI Diagnostics time interval