Free calculators

Three calculators for the parts of a power system study you do most often. Each one shows its formulas, a worked example and the assumptions behind the answer. No account needed.

• $$Z_\text{new} = Z_\text{old}\left(\dfrac{V_\text{old}}{V_\text{new}}\right)^{2}\left(\dfrac{S_\text{new}}{S_\text{old}}\right)$$

  Per-unit converter

  Base current and impedance, and an impedance moved from one MVA and kV base to another.

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• $$I_{3\phi} = \dfrac{I_\text{base}}{Z_s + Z_t}$$

  Fault current calculator

  Three-phase and line-to-ground fault current at a delta–wye-grounded transformer's secondary.

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• $$\Delta V_{3\phi} = \sqrt{3}\,I\,L\,(R\cos\varphi + X\sin\varphi)$$

  Voltage drop calculator

  Feeder voltage drop from current, length, conductor R and X, and power factor.

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