Three methods to improve product safety

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

Pros:

-Increasing component reliability will reduce the system failure rate, thereby also reducing the probability of a safety event.
Mean Time Between Failure (MTBF) and Failure Rate are standard measures of reliability.

 

Cons:

-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

 

-More reliable components are usually more expensive

 

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

Pros:

-Adding redundancy reduces the system failure rate 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.

 

Cons:

-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.

 

-BQR’s Failure Mode and Effects Analysis (FMEA / FMECA) and Fault Tree Analysis (FTA) helps you to analyze the effects and severity of failure mode combinations.

 

-FMECA, FTA and RBD are also offered as a professional service

 

3. Failure Detection and Mitigation 

Pros:

-Failure detection and fail safe mechanisms reduce the severity of the failure effect.

 

-Implementing detection systems may be easier to implement compared to methods 1 and 2.

 

Cons:

-Product / system operation is affected during 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

 

Conclusions

Safety can be achieved by combining the 3 methods described above.

The optimal combination of methods is specific to each product / system.

Examples:

-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

 

Which methods do you use for safety risk reduction?