Independent Source Power Analysis
Independent voltage sources set a voltage across their terminals. They can deliver power, absorb power, or exchange power with other active sources. The answer depends on polarity and current direction. A source that sends current out of its positive terminal normally delivers power. A source that receives current into its positive terminal normally absorbs power. This calculator follows that rule, so the sign is easier to audit.
Why Sign Convention Matters
Circuit books often use the passive sign convention. Under that convention, absorbed power is positive when current enters the positive terminal. Delivered power is the opposite sign. Many mistakes happen when a user multiplies voltage and current without checking direction. This tool records direction for each source. It also separates absorbed power, delivered power, internal loss, and net output.
Advanced Source Options
Real supplies are not always ideal. A battery, bench supply, inverter, or generator may include internal resistance. Current through that resistance creates I squared R loss. The calculator subtracts that loss from delivered output when the source is sending energy outward. It also includes power factor, so RMS AC source estimates can be handled with a practical real power value.
Using Results in Reports
Use the total signed power to check conservation in a circuit study. A negative absorbed value means a source is delivering energy. A positive absorbed value means it is taking energy from the circuit. The energy line converts power into watt hours for the selected time. This helps compare circuit operation during tests, duty cycles, and battery runtime studies.
Best Practice Notes
Use measured terminal voltage when available. Use RMS values for AC work. Use a power factor of one for direct current. Keep current direction consistent with the marked positive terminal. If a dependent source is present, treat it separately. This calculator is intended for independent voltage sources, but the same sign idea can support careful hand analysis.
Quality Checks
Before trusting a result, compare totals with resistor and load power. The delivered power from all sources should match the absorbed power in the rest of the circuit, after rounding. Large differences may show reversed current labels, wrong RMS inputs, or missed internal resistance during final circuit review.