Power system calculations connect network data to practical engineering decisions: bus voltage, power transfer, conductor heating, machine behavior and electrical exposure. Choose the model that answers your question, keep voltage and power bases consistent, and check the assumptions before using the result.
This GridCircuits overview covers nine calculation topics and an additional transmission ring-bus load-flow tool. Each linked calculator puts inputs and results first, followed by original explanations, formulas, worked examples and references.
Which power system calculation do you need?
| Topic | What the tool calculates | Model boundary |
|---|---|---|
| Load Flow Calculator: AC Power Flow & Bus Voltages | Solve a small AC power-flow network for bus voltages, branch MW/MVAr and losses. Includes an editable five-bus example and Newton–Raphson iteration. | Balanced AC power flow; no generator reactive or thermal limit enforcement. |
| Transmission Ring-Bus Load Flow Calculator | Calculate ring-bus section voltages, incoming-circuit power and losses. Open or close six breakers to study bus splitting and source connectivity. | Six-position ideal-breaker topology, common remote source; incoming circuit currents only. |
| Grounding Conductor Sizing: Thermal Area & Tape | Calculate minimum grounding-conductor thermal area and tape thickness from fault current, clearing time and a verified material k factor. | Adiabatic thermal area; touch/step and complete grounding design are separate. |
| Cable Ampacity Calculator: Thermal-Balance Estimate | Estimate steady-state cable current using a reduced thermal model. Enter AC resistance, thermal resistance, temperature limits and other cable losses. | Reduced thermal balance; not a complete Neher–McGrath/IEC 60287 installation rating. |
| Power Swing Calculator: Classical Rotor-Angle Model | Explore rotor angle and slip frequency with a classical swing-equation model. Compare mechanical input with electrical transfer capability. | Classical single-machine dynamics; no relay settings or fault-clearing sequence. |
| Induction Motor Starting Current & Torque Calculator | Calculate induction-motor RMS winding current, slip, air-gap power and torque from a stator-referred per-phase equivalent circuit. | Quasi-steady RMS equivalent circuit; not dynamic acceleration or peak inrush. |
| Transmission Line Calculator: RLGC, Delay & Reflections | Calculate distributed-line AC characteristic impedance and propagation constants, plus lossless travel time and the first two step-wave arrivals. | AC RLGC parameters and lossless step arrivals; no numerical inverse Laplace solver. |
| Per-Unit Calculator: Impedance & Base Conversion | Convert ohms, per-unit impedance and percent impedance. Calculate base current and change between three-phase MVA and line-to-line kV bases. | Magnitude and base conversion; no transformer sequence-path model. |
| Unbalanced Three-Phase Wye Load Calculator | Calculate phase currents, neutral current, neutral displacement and total power for an unbalanced wye load with connected or floating neutral. | Linear sinusoidal wye load; ideal connected or floating neutral. |
| Arc Flash Incident Energy Scaling Calculator | Scale a validated incident-energy result when only arc duration changes. This comparison tool does not perform a complete IEEE 1584 calculation. | Time scaling of validated reference energy; not a complete IEEE 1584 study. |
Start with a consistent calculation basis
Use RMS phasors for steady sinusoidal AC calculations. State whether voltage is line-to-line or phase-to-neutral, whether power is three-phase total or per phase, and whether impedance is in ohms or per unit. A correct equation with inconsistent bases produces the wrong engineering result.
For a balanced three-phase base, Zbase in ohms equals kVbase squared divided by MVAbase. Base current in amperes equals 1000 times MVAbase divided by √3 times line-to-line kVbase. Across a transformer, carry voltage bases through the turns ratio.
Understand the result before applying it
A converged load flow is a solved operating point. It does not establish equipment adequacy, fault duty or dynamic stability. Similarly, a grounding conductor that survives a thermal check does not establish acceptable touch voltage. Read the model boundary shown beside each topic.
Use the worked examples to learn the conventions. Then replace the illustrative data with verified equipment parameters and the operating scenario you are studying. Source strength, topology, clearing time and connected machines can materially change the result.
How ring-bus switching affects load flow
The ring-bus tool models six substation circuit positions connected by breakers. Closing a breaker joins adjacent positions into one electrical bus. Opening one breaker can leave the remaining path intact; several openings can divide the ring into sections. Each section needs a connection to a source.
In an ideal closed-breaker model, internal ring-current sharing is indeterminate. The calculator therefore reports section voltages and incoming-circuit power/current without claiming individual breaker duty. Use actual busbar, circuit and fault data for a detailed breaker assessment.
Arc-flash calculation needs its own model
The available arc-flash tool compares duration while holding the validated reference-study conditions fixed. Its formula is Enew = Ereference × tnew/treference. A complete IEEE 1584 workflow additionally determines arcing current, clearing time, geometry corrections, incident energy and boundary for the applicable current cases.
Frequently asked questions
Are power flow and load flow the same?
In this context, both refer to solving steady-state network voltages and power balance. They differ from fault-current and transient-stability studies.
Can I use these calculators for final settings?
The pages identify their simplified models and excluded checks. Final settings and equipment decisions require verified project data and the applicable engineering study.
Where are the formulas and references?
They are below the calculator on every linked study page, alongside the worked example and assumptions.
References and source context
The topic selection was inspired by Maplesoft’s overview of power-system calculations. GridCircuits uses original explanations, its own teaching examples and browser-based implementations with the explicitly stated scope.