Failure Acceleration

This is a simple model of a power transmission line which employs the GoldSim Reliability module to simulate wear and tear on the lines based on the average electrical load and temperature over time, which can eventually lead to failures. This type of failure is defined relative to a failure mode control variable (FMCV), using an acceleration factor as described below.

Failure Mode Control Variables

Goldsim Reliability elements allow the specification of advanced failure modes. Most failure modes are defined relative to a failure mode control variable (FMCV). This is the variable that is referenced by the failure mode to determine when failure occurs. (For those failure modes that are defined as distributions, the control variable represents the x-axis of a failure distribution plot.)

For FMCV-based failure modes, the failure mode calculates the FMCV “age” that will result in its next failure at the start of the realization, after each time the mode is repaired, and after each time the component is replaced. When the FMCV exceeds this value, the failure occurs.

Each (FMCV-based) failure mode has its own FMCV, which is defined in terms of a specified “base variable” (e.g., total simulation time, operating time, mileage). The FMCV for a particular failure mode and the base variable are related as follows:

FMCV(t) = Initial Value + SUM[ (Base Variablei - Base Variablei-1) * Acceleration ]

FMCV(t) represents the value for the FMCV at time t. The sum is made over all the timesteps from the beginning of the realization (or the time the FMCV was reset) to time t. The Initial Value and Acceleration Factor are user inputs for each failure mode. The FMCV calculation can be reset by certain events such as replacement of the component or repair of the failure mode. This is done by resetting the Initial Value (to a specified FMCV value) and restarting the sum.

This is a simple model of a power transmission line which employs an Acceleration Factor for the FMCV. Its failure is time based, but it depends on the average monthly load on the system and the average monthly temperature. The line typically fails after 35 years (normally distributed with a standard deviation of 0.5 years) with an average load of 1MW, and mean operating temperatures between 0C and 20C.

Average loads that are lower, i.e. 500kW, induce lower wear (in this case, the line wears at 50% of the rate it would transmitting 1MW), while average loads that are higher cause higher wear (transmitting 2MW causes the line to wear twice as fast).

Temperature extremes also cause wear - cold temperatures and the formation of ice increase wear below 0C (wear is multiplied by a factor of three), where high temperatures cause the lines to sag - every increase of 10C beyond 20C increases wear on the lines by a factor of 2.

Both the average load and average temperature are resampled each month, using month-by-month data for both values.

To Open the Model File:

1. Start GoldSim
2. Click on the File and select Open Example...
3. Browse to Reliability Examples
4. Select the file called Acceleration.gsm