Failure Page
The Failure page in the Calculation Properties window for a block specifies failure data for the block. The following table describes the properties that can appear on the Failure page.
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If the component represented by the block can be in standby, you can specify the failure properties to use for the component when it is not in use. A standby component can be online but in standby redundancy or in a standby path due to a standby junction.
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Property
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Description
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Failure Distribution
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The distribution to use to model failure times when the component is in operation. The default is Exponential with a failure rate of 0. When you click this field’s browse button, the Distribution window opens. In it, you select the distribution and specify input parameters. If the block is linked to another item in the System file, you are unable to make a selection in this field. Instead, the failure rate information for the item to which the block is linked is used.
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Duty Cycle Percentage
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This percentage of time that the component is in operation. Alternately, when the component is operated at a load different from its rated load, you can use this property as an acceleration factor:
• If the block is operated continuously at the rated load, then its duty cycle is 100%.
• If the block is operated at the rated load only 50% percentage of the time, then its duty cycle is 50%.
• If the block is continuously operated at a higher load with an acceleration factor of 2, then its duty cycle is 200%.
The default is 100. You can enter any value greater than or equal to zero.
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Standby failure properties
While a component in standby does not typically degrade as quickly as a component that is online and in use, it does still suffer some degradation due to age, and it can still fail. The properties under this heading allow you to supply failure data for a standby component.
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Standby Aging Percentage
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A percentage value from 0 to 100 that adjusts the effective age of the standby component. The default is 0. Examples follow.
• A value of 0 means that the standby component or spare does not age.
• A value of 50 means that after 100 hours in standby, the component or spare is only 50 hours old.
• A value of 100 means that the component ages in standby or storage as if it were operating.
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Standby Failure Detection
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Indicates how a failure of the standby component is detected. Choices are:
• Undetectable until use. When selected, a failure cannot be detected until the standby component is placed in operation.
• Detectable during inspection. When selected, a failure of the standby component can be detected during inspection.
• Self announcing. When selected (default), failure of the standby component can be detected immediately upon occurrence.
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Standby Failure Type
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Indicates how the distribution for the standby component is determined. Choices are:
• Percentage of online failure distribution. When selected (default), the failure rate of the standby component is a specified percentage of the failure rate for an online component. In this case, Standby FR Percentage becomes available so that you can specify the percentage value.
• Specified failure distribution. When selected, the distribution for the standby component is different than that for the online component. In this case, Standby Failure Distribution becomes available so that you can select the distribution to use for the standby component and specify input values for its parameters.
• Same as online failure rate. When selected, the failure rate for the standby component is the same as the failure rate for the online component.
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Standby FR Percentage
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A percentage value from 0 to 100 that adjusts the failure rate of the online component to reflect the failure rate of the standby component. The default is 0. For example, a value of 50 means that the failure rate of the standby component is half that of the online component. This field is available only when Percentage of online failure distribution is selected (default) for Standby Failure Type.
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Standby Failure Distribution
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The distribution to use to model failure times when the component is in standby. This field is available only when Specified failure distribution is selected for Standby Failure Type. The default is Constant Time with a failure rate of 0 hours. When you click this field’s browse button, the Distribution window opens. In it, you select the distribution and specify values for its input parameters. Additional information about various distributions appears in Failure and Repair Distributions.
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