Transmission & Grid calculator
Symmetrical Components Calculator
Resolve three phase phasors into positive-, negative- and zero-sequence components using the Fortescue transformation.
GridBasis: Fortescue symmetrical components · IEC 60909 / IEEE power-system analysis
Results
- Enter values to calculate
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Formula
With a = 1∠120°:
V0 = (Va + Vb + Vc) / 3
V1 = (Va + aVb + a²Vc) / 3
V2 = (Va + a²Vb + aVc) / 3
Worked example
A balanced positive-sequence set of 120∠0°, 120∠−120° and 120∠120° gives approximately V1 = 120 and V2 = V0 = 0.
Assumptions and standards
- All three inputs must use the same unit and reference.
- Angles are electrical degrees.
- The calculator uses an ABC phase sequence convention.
Formula and data last verified: October 2026.
Frequently asked questions
What does negative-sequence voltage indicate?
Negative sequence is a measure of phase unbalance. It is especially important for rotating machines because it produces counter-rotating magnetic fields and extra heating.
What does zero sequence indicate?
Zero-sequence components are equal in magnitude and angle in all three phases. They are strongly associated with ground-return paths and ground faults.
Can I use these results for final design?
Use them for preliminary design and checking. Final designs must be verified by a qualified engineer against the code edition and standards adopted where the work is installed.
Is my data sent anywhere?
No. Every calculation runs in your browser. Nothing you type is uploaded or stored on our servers.