Short Circuit

pandapower OpenDSS ANSI/IEEE C37

Short Circuit calculates fault currents on the network so you can size breakers, check withstand, and feed protection studies. Two engine tabs are available and are not interchangeable: Pandapower can run IEC 60909 or ANSI/IEEE C37 (beta) (tick boxes on that tab); OpenDSS runs a native Thévenin fault study.

When to use

• Breaker and fuse interrupting ratings
• Relay pickup and protection coordination
• Grid-code style IEC 60909 studies (Pandapower tab, IEC 60909 tick)
• North American / Canadian projects requiring ANSI/IEEE C37 duties (Pandapower tab, ANSI/IEEE C37 tick — currently beta; default 60 Hz, prefault 1.0 pu)

How to run

1. Confirm the diagram already solves in Load Flow with the same engine you will use for faults.
2. Click Simulate → Short Circuit and choose the engine tab. On Pandapower, tick IEC 60909 or ANSI/IEEE C37 (beta).
3. Set fault type (3-phase, 2-phase, or 1-phase), case (maximum or minimum), and Fault location (All busbars, or User Selection of one or more busbars). For IEC 60909 single-phase minimum, fill the External Grid Short Circuit tab, including min zero-sequence ratios.
4. Read currents on the diagram. A red thunder mark sits on each faulted busbar (all buses, or the User Selection). It is removed when you run the next study of any type. Pandapower writes buses, lines, transformers, and the external grid. OpenDSS writes bus currents only; line, transformer, external-grid, and wind-turbine result boxes are marked as not provided. The Short-Circuit Dashboard opens automatically after a successful run.
5. Optional: tick Export Pandapower Python Code (IEC Pandapower), Export OpenDSS Commands (OpenDSS tab), or Export PDF Engineering Report before you run.
6. Use those values for Arc Flash if you need incident energy next.

ANSI/IEEE C37 (North America / Canada) — beta

On the Pandapower tab, tick ANSI/IEEE C37 when the project or utility requires ANSI/IEEE C37 short-circuit duties (typical in Canada and the United States). This is not IEC 60909 with a different label.

The study follows the North American three-network method used in IEEE C37.010 (and described in IEEE Std 141, the Red Book). Electrisim builds three separate impedance networks from the same diagram:

1. First-cycle (½-cycle) — subtransient machine reactances. Momentary / close-and-latch basis.
2. Interrupting — contact parting time (default 3 cycles). Transient reactances; motors reduced or removed per ANSI practice.
3. 30-cycle — steady-state network (induction motors out).

Prefault voltage is applied directly (default 1.00 pu). There is no IEC voltage factor c and no IEC K_G / K_T correction factors. Asymmetry uses the calculated fault-point X/R: first-cycle peak from a fully offset wave, interrupting duty from the remaining DC component at contact parting (compared with the C37.010 X/R = 17 test circuit for symmetrically rated HV breakers), and extra first-cycle derating for LV devices when system X/R exceeds the C37.13 (6.6) or UL 489 (4.9) test circuit.

Set generator ANSI machine type (turbo, hydro, etc.) and Switch interrupting / momentary ratings on the Short Circuit tab for duty comparison. Device class can be auto (from voltage) or C37.010 / C37.13 / UL 489 / C37.013.

IEC 60909 vs ANSI/IEEE C37

ANSI results

Currents are written to diagram result boxes on buses, lines, and transformers, and listed in the ANSI results dialog (and optional TXT export).

ANSI input parameters

ANSI limitations (beta): do not mix ANSI currents with IEC-rated equipment. Single-phase line/transformer currents are not published. Arc flash still uses the IEC 60909 path. Spot-check a few duties against your C37.010 tables or a known hand calc before relying on ratings.

Fault types

Electrisim supports three types of short circuit faults:

• Three-Phase Fault (3ph): Symmetrical fault affecting all three phases. Typically produces the highest fault current. Used for symmetrical interrupting capacity rating.
• Two-Phase Fault (2ph): Fault between two phases. Produces lower fault current than three-phase. Used for phase-to-phase protection.
• Single-Phase Fault (1ph): Fault between one phase and neutral/ground. Includes zero-sequence impedance of the network and of the External Grid. Critical for ground-fault protection and neutral sizing. IEC 60909 maximum uses r0x0_max / x0x_max; minimum uses r0x0_min / x0x_min.

Fault location is independent of fault type. All busbars (default) applies the chosen fault at every bus. User Selection applies it only at the busbars you tick in the dialog (busbars selected on the diagram are pre-ticked). Unselected bus result boxes show “Fault not applied”. A red thunder sign marks each faulted bus on the diagram until the next simulation.

Input Parameters (IEC 60909)

These fields appear when IEC 60909 is ticked on the Pandapower tab. For ANSI parameters see ANSI/IEEE C37 above.

Short-Circuit Dashboard

After a successful short-circuit run (Pandapower IEC, ANSI/IEEE C37, or OpenDSS), Electrisim opens the Short-Circuit Dashboard: the same floating panel pattern as the load-flow Network Health Dashboard, but KPIs use fault currents (Ikss, Ip, Ith, X/R) instead of voltage and loading.

Short-Circuit Engineering Report (PDF)

Tick Export PDF Engineering Report in the Short Circuit dialog (any engine tab), or click Export Report on the Short-Circuit Dashboard after a run. The PDF includes cover metadata, executive summary with fault-current KPIs, single-line diagram pages, bus and branch tables, ANSI device duties when applicable, and an issues list.

Calculation Cases (IEC 60909)

According to DIN/IEC EN 60909, different calculation cases are used:

• Maximum Case (Ik"): Highest fault current (typically for breaker sizing). Assumes maximum generation, minimum impedances, voltage = 1.1 pu (c_max). External Grid uses s_sc_max_mva, rx_max, and for 1-phase faults r0x0_max / x0x_max.
• Minimum Case (Ik'): Lowest fault current (typically for protection coordination). Assumes minimum generation, maximum impedances, voltage = 0.9 pu (c_min). External Grid uses s_sc_min_mva, rx_min, and for 1-phase faults r0x0_min / x0x_min.

Output Results (IEC 60909)

The IEC 60909 analysis provides detailed fault current information:

Algorithm Details (IEC 60909)

The IEC path follows DIN/IEC EN 60909:

• Voltage Factor (c): c_max = 1.1 for maximum case, c_min = 0.9 for minimum case (low voltage)
• Impedance Correction: Generator and transformer impedances are corrected according to the standard
• Far-from-Generator Approximation: Used when fault is far from generators (symmetrical current decays quickly)
• Near-to-Generator: Special handling when fault is close to generators (asynchronous contribution)
• Solution Method: Matrix inversion or LU factorization of network admittance matrix

Limitations and Considerations

Short Circuit based on OpenDSS

In addition to Pandapower IEC 60909 and ANSI/IEEE C37 (beta), Electrisim offers short circuit calculation based on OpenDSS. In the Short Circuit dialog, select the OpenDSS tab to run a conventional fault study using the Open-Source Distribution System Simulator.

OpenDSS fault study (Solve Mode=FaultStudy) computes for every bus:

• Initial symmetrical short-circuit current (I''_k, ikss) in kA
• Peak short-circuit current (i_p, ip) in kA — Electrisim reports ip = 1.8 · √2 · ikss (fixed κ = 1.8), not the IEC κ(R/X) peak
• Thermal short-circuit current (I_th, ith) in kA — copied from ikss (OpenDSS does not compute the IEC 1 s thermal equivalent)
• Positive-sequence short-circuit resistance (R_k, rk_ohm) and reactance (X_k, xk_ohm) in ohms from Zsc1

Fault type (e.g. 3-phase), Fault location (All busbars or User Selection), and frequency can be set in the OpenDSS tab. Results are shown on the diagram at each faulted busbar. Line, transformer, external-grid, and wind-turbine result boxes are updated to state that OpenDSS does not provide short-circuit currents for those elements (FaultStudy is bus Isc/Zsc only). Optional checkboxes: Export OpenDSS Commands (replay script .txt), Export OpenDSS Results (tabular .txt), and Export PDF Engineering Report (see Short-Circuit Engineering Report). This option uses the same network model as OpenDSS load flow (buses, lines, loads, generators, external grid).

Pandapower vs OpenDSS short-circuit results

The two engines can be run on the same diagram and will usually not return the same kA. That is expected: they implement different methods, not two numerical solvers of IEC 60909.

Typical pattern on a wind-farm feeder: OpenDSS Ikss is a few percent higher on MV/LV turbine buses (machine Xdpp infeed) and about 1/c_max lower on a capacitor LV bus with no turbine (no IEC voltage factor). Peak currents differ more because of the κ formula.

OpenDSS references: Fault Studies, Fault Study Mode, Bus.Isc().

Technical References

Based on: pandapower Short-Circuit and DIN/IEC EN 60909 (Pandapower IEC); IEEE C37.010 / C37.13 / UL 489 / C37.013 and IEEE Std 141 three-network method (Pandapower ANSI/IEEE C37, beta); OpenDSS Fault Studies (OpenDSS).

Algorithm Type: Pandapower IEC: symmetrical components with impedance-based fault calculation following IEC 60909. Pandapower ANSI: three impedance networks plus X/R multiplying factors (does not call IEC calc_sc). OpenDSS: conventional fault study with Thévenin equivalent and open-circuit voltage per bus.

Documentation References: 📘 pandapower Short-Circuit 📘 Running a Short-Circuit Calculation 📗 OpenDSS Fault Studies

Standards: IEC 60909: Short-circuit currents in three-phase a.c. systems (Pandapower IEC); IEEE C37.010, IEEE C37.13, UL 489, IEEE C37.013, IEEE Std 141 (Pandapower ANSI, beta).