B11 LMSS Module 3 Rev 2

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following is a common electrical failure mode?

Temperature fluctuation

Coil Failure

Short circuit of outputs (correct)

Seal Failure

What might occur due to a loss of PES/PLC memory?

Noise interference

Loss of safety functions (correct)

Fluid leaks

Diminished response time

Which of the following pneumatic failure modes refers to contamination from the surroundings?

Temperature

Ingress of contaminants (correct)

Moisture

Line blockage

What is a potential result of valve element position failure in fluid power systems?

Improper fluid flow regulation Signup and view all the answers

Which failure mode is characterized by a complete loss of hydraulic power?

Complete Loss of Fluid Power Signup and view all the answers

What is a consequence of temperature variation in pneumatic systems?

Diminished response time Signup and view all the answers

Which fault could result from external signal errors in electrical systems?

False actuator/input signal Signup and view all the answers

Which of the following represents a potential cause of coil failure in fluid power systems?

Incorrect wiring connections Signup and view all the answers

Which of the following is the first step in the risk assessment process?

Prepare for and Set Limits of the Assessment Signup and view all the answers

What determines the level of risk in a risk scoring system?

Probability of Occurrence and Severity of Harm Signup and view all the answers

What is the purpose of identifying risk reduction measures?

To manage tasks-hazard pairs with unacceptable risk levels Signup and view all the answers

Which term describes a part of a machine that includes safety-related functions?

Machine Control System Signup and view all the answers

When assessing initial risk, which scoring combination results in a 'High' risk level?

Serious severity with likely occurrence Signup and view all the answers

What is the next step after assessing residual risk?

Validate Solutions Signup and view all the answers

Which of the following probabilities corresponds with a 'Negligible' risk level for severity classified as 'Minor'?

Remote Signup and view all the answers

What is the final step of the risk assessment process as described?

Document Results Signup and view all the answers

Which step involves determining failure modes and considerations?

Conduct risk assessment Signup and view all the answers

What is the first action to take when risk is not acceptable?

Identify risk reduction measures Signup and view all the answers

What is the first step in machinery safety?

Conduct a risk assessment Signup and view all the answers

Is fixed guarding part of the safety related part of a control system?

No, it is separate from SRP/CS Signup and view all the answers

A safety function applies to which of the following?

Both inputs and outputs Signup and view all the answers

What should be evaluated to ascertain how much risk is reduced by the SRP/CS?

Effectiveness of the system Signup and view all the answers

Which step involves defining safety functions for the system?

Step 3 Signup and view all the answers

What aspect should be determined to define the required reliability design specification?

Safety function requirements Signup and view all the answers

Which of the following is NOT a step in determining required reliability?

Identify legal standards Signup and view all the answers

What is included in the basic elements required for a safety function?

Input, logic, and output elements Signup and view all the answers

Monitoring and diagnostic coverage are applied to manage which aspect?

Failure Modes/Fault considerations Signup and view all the answers

Which step outlines the application of specific design requirements and examples?

Step 9 Signup and view all the answers

What is required for selecting a reliability design specification for a circuit?

Using methodologies from ISO 13849-1, EN 954-1, or the B11 series standards Signup and view all the answers

Which of the following methodologies is NOT mentioned for reliability design specification?

Market demand analysis Signup and view all the answers

What does the term 'Residual Risk' refer to in the context of risk reduction measures?

The remaining risk after implementing risk reduction measures Signup and view all the answers

What is the main focus of the reliability design specifications discussed?

Ensuring the overall reliability of circuits Signup and view all the answers

Which statement is true regarding control reliability ratings in the context provided?

Capability ratings of individual components must be used carefully. Signup and view all the answers

What is the acceptable risk level in relation to initial risk?

It should equal zero risk Signup and view all the answers

Which of the following best describes 'Zero Risk'?

A theoretical state where no risks exist Signup and view all the answers

Which is an example of a risk reduction measure mentioned?

Inherently safe design measures Signup and view all the answers

What is the first step in the functional safety process?

Conduct risk assessment and determine risk reduction measures Signup and view all the answers

Which of the following is NOT considered a fault exclusion basis?

Fail-safe design practices Signup and view all the answers

What must be defined for each safety function to ensure reliability?

Reliability design specification Signup and view all the answers

In the functional safety process, when are the failure modes of circuit devices evaluated?

When applying specific design requirements Signup and view all the answers

What type of coverage is to be determined as part of the functional safety process?

Diagnostic coverage Signup and view all the answers

Which step involves defining the basic input, logic, and output elements required?

Step 5 Signup and view all the answers

At which stage in the functional safety process is risk reduction measures specifically involving the SRP/CS identified?

Step 2 Signup and view all the answers

Which of the following actions is carried out to manage failure modes during design?

Determine monitoring and diagnostic coverage Signup and view all the answers

What may limit the ability to detect certain faults during operation?

Mitigating design and construction methods Signup and view all the answers

Which stage evaluates the effectiveness of the entire safety system?

Step 10 Signup and view all the answers

Study Notes

Electrical Failure Modes

Short circuit can occur in outputs, external wiring, or actuators, causing loss of switching function.
PES/PLC program alterations due to unsecured logic or programming errors can lead to malfunctions.
Loss of PES/PLC memory poses significant risks to system operation.
Safety device failures may result from issues with internal components.
False actuator/input signals can result from noise or external signal errors, leading to improper system responses.

Fluid Power Failure Modes

Seal failure can lead to leakage and loss of hydraulic fluid.
Spring or coil failure impacts the mechanical actuation within systems.
Loss of electrical power can be complete or partial, affecting system operation.
Diminished response time and valve position failures can create inefficiencies and safety hazards.
Pilot section or mounting orientation failures influence system stability and functioning.
Inertial forces and connector failures (hoses/tubes) can restrict fluid flow.

Pneumatic Failure Modes

Adverse temperature and moisture levels can damage pneumatic systems.
Electrical issues may lead to control failures.
Lack of lubrication contributes to increased friction and wear.
Line blockages or muffler restrictions impede airflow.
Ingress of contaminants can degrade system performance.

Hydraulic Failure Modes

Closed hydraulic systems need to manage wear as contaminants can amplify failure rates.
Essential to monitor temperature, moisture, and air levels to ensure system integrity.
Particle contamination poses significant risks to fluid power operation.

Risk Assessment Process

Start with a risk scoring system to evaluate severity and probability of occurrence.
Implement a hazard control hierarchy to reduce risks effectively.
Document assessment outcomes for future reference.

Scoring Systems

Risk assessment evaluates severity of harm against the likelihood of occurrence.
Categories include catastrophic, serious, moderate, and minor outcomes linked to the probability of occurrence (very likely, likely, unlikely, remote).

Conduct thorough risk assessments to identify safety functions and reliability specifications.
Utilize SRP/CS to define critical safety functions and their corresponding reliability requirements.
Implement design requirements for all elements of a control system.

Reliability Specifications

Establish reliability design specifications based on ISO standards (e.g., ISO 13849-1).
Control reliability ratings cannot solely dictate overall circuit reliability; individual component ratings are insufficient.
Include fault consideration as part of the design process to enhance circuit reliability.

Functional Safety Process

Conduct assessments and identify risk reduction measures related to SRP/CS.
Define essential safety functions and requisite reliability for each function.
Evaluate the effectiveness of the safety system continuously to ensure compliance and safety.

Fault Exclusion

Certain faults may not be detected during operation, emphasizing the need for effective design and installation to minimize occurrence.
Low probability of certain faults can justify exclusion based on established engineering practices and application-specific technical requirements.
Evaluate failure modes continually to maintain the integrity of devices, actuators, and controllers.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your understanding of various electrical failure modes, including short circuits, programming errors in PES/PLC systems, and faults in safety devices. This quiz covers critical aspects of electrical system failures and their impact on performance. Prepare to evaluate scenarios and deepen your knowledge of electrical safety.