Cameo Safety and Reliability Analyzer 18.0 SP2 Documentation

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After the mitigation phase, risks (Safety Analysis Items) can be further described in a Risk Reduction Table. Since Risk Reduction Tables are based on Generic Tables, the toolbar and the Criteria area work in the same manner.

A Risk Reduction Table allows you to analyze the safety aspect of your model both before and after the mitigation. This gives you an opportunity to evaluate the effectiveness of recommended risk reduction actions. Each row in a table represents a Safety Analysis Item, and table columns represent the properties of each Safety Analysis Item in the table. In a Risk Table, you can:

  • Create a new Safety Analysis Item directly in the table, or add an existing one.
  • Edit the properties of Safety Analysis Items directly in the table.
  • Generate a risk analysis report, or export the table into a CSV or HTML file format.


A Risk Table has the following columns:

Table column nameDescription
IdSafety Analysis Item ID.
FMEA ReferenceThe reference to an FMEA Item.
Initiating CauseA short description of a Safety Analysis Item.
HazardA potential source of Harm.
Sequence of Events

Sequence of Events leading to a Hazardous Situation.

Every Sequence of Events can have a default P1 value assigned as its property. To assign a value, open the Specification window of a Sequence of Events, and set the desired P1 value.

Usage information

If you add a Sequence of Events with a specified P1 value to a certain row of a Risk Reduction Table for the first time, this value is automatically entered into an appropriate cell of the P1 column. The value is entered even if the cell already has a value specified. You can manually change the P1 value that was automatically added to a Risk Reduction Table together with a Sequence of Events. This action does not change the default P1 value assigned to this specific Sequence of Events element.

Hazardous Situation

A situation in which a subject or an object of the environment is exposed to one or more Hazards.

Every Hazardous Situation can have a default P2 value assigned as its property. To assign a value, open the Specification window of a Hazardous Situation, and set the desired P2 value.

Usage information

If you add a Hazardous Situation with a specified P2 value to a certain row of a Risk Reduction Table for the first time, this value is automatically entered into an appropriate cell of the P2 column. The value is entered even if the cell already has a value specified. You can manually change the P2 value that was automatically added to a Risk Reduction Table together with a Hazardous Situation. This action does not change the default P2 value assigned to this specific Hazardous Situation element.

Harm

Damage to the health of people, damage to the property or environment, or both.

Every Harm can have a default severity (S) value assigned as its property. To assign a value, open the Specification window of a Harm, and set the desired Severity value.

Usage information

If you add a Harm with a specified severity (S) value to a certain row of a Risk Reduction Table for the first time, this value is automatically entered into an appropriate cell of the S column. The value is entered even if the cell already has a value specified. You can manually change the severity (S) value that was automatically added to a Risk Reduction Table together with a Harm. This action does not change the default severity value assigned to this specific Harm element.

S

Severity is the quantitative evaluation of the Harm that is caused if exposed to a Hazard. The valid values of this property are 1 to 4 (1 representing the lowest severity).

Click an appropriate column cell to select its value from a drop-down list.

P1

Probability of a foreseeable Sequence of Events leading to a Hazardous Situation. The valid values of this property are 1 to 5 (1 representing the lowest probability).

Click an appropriate column cell to select its value from a drop-down list.

P2

Probability of a Harm occurring when exposed to a Hazard. The valid values of this property are 1 to 5 (1 representing the lowest probability).

Click an appropriate column cell to select its value from a drop-down list.

PThe function of P1 and P2.
D

Detectability measures the likelihood of discovering and correcting a Hazard prior to Harm occurrence. The valid values of this property are 1 to 5 (1 representing the highest detectability).

Click an appropriate column cell to select its value from a drop-down list.

C

Correctability is the rate of relative ease of mitigating a certain risk. The valid values of this property are 1 to 5 (1 representing the lowest correctability).

Click an appropriate column cell to select its value from a drop-down list.

PU

Product Utility shows the clinical benefits of a product taking into account the risks it holds. The valid values of this property are 1 to 5 (1 representing the highest clinical benefits that outweigh the risks).

Click an appropriate column cell to select its value from a drop-down list.

RiskA customizable function of P and S.
Risk Control Measures DescriptionA brief, qualitative description of the proposed method of risk control.
Risk Control MeasuresA reference to the safety requirement which mitigates the risk.
MitigatorsA reference to any element which satisfies the related safety requirement.
Reduced S

Reduced severity is the quantitative evaluation of the Harm that is caused if exposed to a Hazard after the mitigation (or simply - severity value after the mitigation). The valid values of this property are 1 to 4 (1 representing the lowest severity).

Click an appropriate column cell to select its value from a drop-down list.

Reduced P1

Probability of a foreseeable Sequence of Events leading to a Hazardous Situation after the mitigation. The valid values of this property are 1 to 5 (1 representing the lowest probability).

Click an appropriate column cell to select its value from a drop-down list.

Reduced P2

Probability of a Harm occurring when exposed to a Hazard after the mitigation. The valid values of this property are 1 to 5 (1 representing the lowest probability).

Click an appropriate column cell to select its value from a drop-down list.

Reduced PThe function of Reduced P1 and Reduced P2.
Reduced D

Reduced detectability measures the likelihood of discovering and correcting a Hazard prior to Harm occurrence, but after the mitigation (or simply - detectability value after the mitigation). The valid values of this property are 1 to 5 (1 representing the highest detectability).

Click an appropriate column cell to select its value from a drop-down list.

Reduced C

Correctability is the rate of relative ease of mitigating a certain risk if it is faced after the mitigation. The valid values of this property are 1 to 5 (1 representing the lowest correctability).

Click an appropriate column cell to select its value from a drop-down list.

Reduced PU

Reduced Product Utility shows the clinical benefits of a product taking into account the risks it holds after the mitigation (or simply - product utility value after the mitigation). The valid values of this property are 1 to 5 (1 representing the highest clinical benefits which outweigh the risks).

Click an appropriate column cell to select its value from a drop-down list.

Reduced RiskA customizable function of Reduced P and Reduced S.
Use RelatedThe property indicating a Hazard's relation to device usage. The valid values of this property are true or false.


Creating a Risk Reduction Table

To keep your model clean and simple, create a Risk Table in the package that contains the Safety Analysis Items to be included in the table.

 

To create a Risk Reduction Table


  1. Do one of the following:
    • Right-click the Package in which you want to create a Risk Reduction Table, and, from the menu, select Create Diagram.
    • Select the Package wherein you want to create a Risk Reduction Table, and click the Create Diagram button on the main toolbar.
  2. Click Risk Reduction Table under the Safety and Reliability Analysis group.
  3. If needed, change the name of the newly created Risk Reduction Table

A new Risk Reduction Table has been created in the selected Package. Now, you should add Safety Analysis Items to the table, as described in the next section.


Adding Safety Analysis Items to a Risk Reduction Table

There are two ways to add Safety Analysis Items to a Risk Reduction Table:

  • Create new Safety Analysis Items directly in the table.
  • Add existing Safety Analysis Items to the table.

 

Productivity tip

To make your work quicker, you can add existing Safety Analysis Items to a Risk Table by dragging them directly to the table. Simply select one or more Safety Analysis Items in the model browser, and drag them to a Risk Table. New rows for the added elements are created automatically.

 

To create a new Safety Analysis Item in a Risk Reduction Table


  • Do one of the following:

-Click the Add New button on the table toolbar.
-Press Insert (Cmd+I on Mac OS).

A new row is added to the end of the table. This row already contains a newly created Safety Analysis Item, which also shows up in the containment tree of your model (inside the package containing the Risk Reduction Table on which you are working). Now, you can define the created Safety Analysis Item and its properties directly in the table by double-clicking an appropriate cell.
 

Model structure information

To have a clear model structure, create Safety Analysis Items in dedicated Packages.

 

To add an existing Safety Analysis Item to a Risk Reduction Table


  1. Do one of the following:
    • Click the Add Existing button on the table toolbar.
    • Press Ctrl+Insert (Cmd+E on Mac OS).
  2. In the open dialog, select the Safety Analysis Item you want to add to the table. To select multiple elements, click , and add the desired Safety Analysis Items to the Selected elements area on the right side of the dialog.
  3. Click OK.

Selected Safety Analysis Item(s) are now added to the Risk Reduction Table as new row(s). You can change the properties of the added elements directly in the table by double-clicking an appropriate cell.

Readability tip

To promote information readability, you can wrap table text the following way:

  1. Click on the table toolbar.
  2. In the drop-down menu, select Wrap Text.
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