The Generator Runtime Calculator calculates how many days a generator can support its critical loads during a power outage. This information is an input for characterizing redundant systems in the TRN risk assessment methodology as part of Baseline Development (BD) Action 3. This tool provides two different options for calculating runtime:

1. If daily consumption (kWh) is known or a reliable estimate is available
2. If daily fuel consumption is unknown, but generator size (kW) is known

Using either of these options, you will obtain an output establishing the number of days that current redundant generator systems will be able to meet critical loads. This analysis provides a high-level estimate. For users who have done or are planning to do more refined assessments of the runtime capabilities for their redundant systems, those estimates may be more appropriate to use as inputs for the TRN analysis. This tool provides estimates for runtime only for generators using fossil fuels. For other types of electric redundant systems, the user should use other resources to characterize their runtime capabilities.

To see the calculations behind the results, click the “Show Calculations” checkbox. Click “Example” to see an example analysis including entered data and results.

Calculator related questions, suggests, and issues can be submitted here: Submit Feedback

Select the fuel type used by your generator. Note that natural gas is not included as a fuel type for generators in this tool. Natural gas generators are connected directly to a natural gas line. Unless a natural gas disruption has also occurred, a natural gas generator will have an "infinite" runtime. However, natural gas generator manufacturers recommend running for no longer than 500 hours at a time so the generator can cool down and any required oil changes or filter replacements can be conducted.