Three methods to reduce safety risks
Today’s products and systems are more complex than ever. As a result, technical failures are unavoidable.
It is however possible to decrease the probability that a failure will result in a severe accident.
Reducing safety risk is critical in order to achieve customer safety requirements as well as boost your company reputation.
Following are 3 methods for reducing risk, each has its advantages and disadvantages:
1. Increase Components’ Reliability
-Increasing component reliability will reduce the expected number of product / system failures, thereby also reducing the probability of a safety event.
Mean Time Between Failure (MTBF) and Failure Rate are standard measures of reliability.
-If the components were already manufactured, increasing their reliability requires root cause analysis and costly research
-If components are COTS, integrators have little control over their design and reliability
BQR solution for increasing reliability:
-BQR’s fiXtress software can detect electronic circuit design errors during design, greatly reducing probability of field failures, as well as reducing development time.
fiXtress also includes MTBF calculation according to leading standards.
– fiXtress analysis is also offered as a professional service, this allows you to focus on your core technology while benefiting from BQR’s experience
2. Add Redundancy
-Adding redundancy reduces the probability of product / system failure because several failures are required rather than a single failure.
There are several types of redundancies:
Hot redundancy: Redundant unit is operating and quickly takes over when primary unit fails.
Standby: Backup unit is not operating, and only starts to operate after primary unit failure. This may incur downtime during transition to the backup unit.
Load sharing: several unit share a load. When a unit fails the other units compensate by working harder, this increases their failure rate.
-More components increase product / system cost
-More active components reduces MTBF, therefore more maintenance will be required
-If redundant components are identical, common cause failures may occur
-May require a failure detection mechanism for switching when one component fails, failure of the switching mechanism should also be considered
BQR solution for redundancy and safety analysis:
-BQR’s RBD software includes reliability allocation and calculation analyses:
Allocation is used during early design to decide on the redundancy strategy.
Calculation is used later to verify that the detailed design meets the reliability requirements.
-FMECA, FTA and RBD are also offered as a professional service
3. Detect and Mitigate Failures
-Quick failure detection is key for reducing the severity of the failure effect.
Example: if signaling data to a train is lost, and the train unit is not aware of the problem, the train may continue to move fast, leading to a potential severe accident.
If however, the train unit detects the communication failure, the train operator may stop the train and communicate by alternative means with the control center, thereby mitigating the potential accident.
-Implementing detection systems may be easier to compared to methods 1 and 2 using e.g. Simple Network Management Protocol (SNMP).
-Product / system operation is affected during failure. In the previous example, the train had to stop due to the communication failure.
BQR solution for failure detection:
-BQR’s unique testability analysis software helps you to create the optimal Built In Test (BIT) policy for high coverage of failures
-Testability Analysis is also offered as a professional service
Safety can be achieved by combining the 3 methods described above.
The combination is specific to each product / system.
-Critical equipment undergoes extensive production control and testing before fielding in order to achieve high reliability
-Redundancies are very common in systems that operate in hard to reach locations
-Many electronic circuits are designed with several BITs for power-up, continuous operation, and maintenance