Scenarios

Scenarios are operating cases of your single-line diagram: which breakers are open or closed, which equipment is in or out of service, and how the system is loaded. You can run calculations for each case, compare them, and take the worst case at each bus without changing your base design.

What scenarios are

A scenario stores the operating values and harmonic study inputs that differ from your base design. Your base design, called Base, is the drawing itself: its equipment, ratings and connections.

A scenario can change:

• whether any component is in service
• whether a breaker or switch is open or closed
• load power, power factor, and demand, diversity and utilization factors
• whether a motor is running when a fault starts
• transformer tap position
• generator output, power factor and minimum load
• which bus is the swing bus
• the utility's fault level and operating voltage
• the energized steps of a capacitor bank
• harmonic source spectra, reactor settings and supported harmonic network models

Other equipment values, such as nameplate ratings, cable lengths and sizes, belong to Base. In a scenario they are greyed out in the properties panel. To study different equipment, change it in Base.

Common uses:

• Comparing peak load with normal load
• Studying the impact of a generator going offline
• Opening or closing a tie breaker
• Evaluating different transformer tap positions
• Finding the worst arc flash energy and fault duty across operating modes, such as a double-ended lineup with its tie open, its tie closed, or one main out

Utility fault levels, such as a maximum and a minimum, are not scenarios: enter them as fault cases on the utility.

Harmonic overrides are edited in the component's Study tab and leave Base unchanged. A capacitor bank's Energized Steps is on its Equipment tab; in a scenario only that field and In service can change. See Run a harmonic study for source profiles, capacitor switching and reactor comparisons.

How scenarios work

Every project has a baseline scenario, Base, that represents your drawing. When you create a new scenario, it starts with all the same values as Base. You then change specific operating values or harmonic study inputs, and only those changes are stored as overrides.

For example, if your base design has a load drawing 100 kW, and you create a "Peak Load" scenario where you change that load to 150 kW, the scenario stores only the single override: the load's active power changed to 150 kW. Every other value comes from Base.

All scenarios share one drawing. Adding, deleting or wiring components while in a scenario changes the drawing for every scenario.

Creating a scenario

1. Click the scenario selector in the editor header. It shows the active scenario's name, such as Base.
2. Select New Scenario.
3. Enter a descriptive Name (e.g., "Generator Offline" or "Tie Breaker Closed").
4. Click Create Scenario. The new scenario becomes the active scenario.

> Note: Scenario names must be unique within a project. To add a description, click the edit button (Edit scenario) in Manage Scenarios....

Switching between scenarios

Use the scenario selector in the canvas header to switch the active scenario. When you select a scenario:

• All override values from that scenario are applied to the displayed component data
• The base design values remain unchanged underneath
• Calculations run against the active scenario's effective values

Switch back to Base at any time to see your base design values.

Editing scenario overrides

To add or change overrides in a scenario:

1. Select the scenario you want to edit from the scenario selector.
2. Select a component on the canvas.
3. In the properties panel, change the operating value you want to override (e.g., change a load's active power from 100 kW to 150 kW).
4. The change is stored as an override in the active scenario. Your base design value remains 100 kW.

You can also view and edit all overrides for a scenario in a table format:

1. In the scenario selector, select Manage Scenarios....
2. Click the parameter table button (Open parameter table) on the scenario you want to inspect.
3. Review and modify overrides across all components in the table.

Opening and closing devices and wires

A scenario is an operating case, so it holds which breakers, fuses, switches and ties are open. To change one:

1. Select the scenario from the scenario selector, or Base to change the base design.
2. Right-click the device or wire on the canvas.
3. Choose Open or Close. For a transfer switch, choose Throw A, Throw B or Open.

The change applies at once. In a scenario it is stored as that scenario's override; in Base it changes the device or wire itself. Choosing the Base state again in a scenario removes the override. Press Cmd+Z (Ctrl+Z) to undo the change in one step. Studies already run for that scenario, or for Base, are marked out of date.

An open device is drawn with its load-side lead broken and labelled OPEN. An open wire is drawn dashed and labelled OPEN. A transfer switch's blade points at the selected throw. A component that is out of service is faded and labelled OUT OF SERVICE.

> Note: A tie drawn as a plain wire, without a breaker or switch, can be opened in one scenario and closed in another the same way.

Buses with no supply

Opening a feeder, pulling a fuse, opening a wire or taking a component out of service can leave part of the diagram with no source in that scenario. The studies still run. They solve the part that has a supply and show each bus, cable, load and device beyond the opening as No supply:

• Short circuit gives those buses no fault current. Equipment ratings are not checked against them in that scenario, because there is no fault duty there; the scenarios where they are fed carry their duty.
• Load flow treats the loads beyond the opening as unserved and solves the rest.
• Arc flash records those buses as No supply. They get no incident energy and no label from that run.

A bus that nothing in the diagram joins to a source, even with every device and wire closed and every component in service, is a drawing problem instead. The study does not run and names the bus to connect or delete.

Seeing what differs from Base

In a scenario, a component or wire whose value differs from Base carries a small compare marker next to its symbol. Hover over it, tab to it, or tap it to read what differs, for example "Open here, closed in Base". The marker disappears when the scenario's value matches Base again.

Cloning scenarios

To duplicate an existing scenario along with all its overrides:

1. In the scenario selector, select Manage Scenarios....
2. Click the clone button (Clone scenario) on the scenario you want to duplicate.
3. Enter a name for the cloned scenario.
4. Click Clone Scenario. The new scenario contains all the same overrides as the source.

Cloning is useful when you want a variation of an existing operating case, such as the same outage at peak load.

Running calculations per scenario

To run power flow or short circuit analysis for a specific scenario:

1. Select the scenario from the scenario selector in the canvas header.
2. Run the calculation as you normally would.
3. Results reflect the active scenario's effective component values.

Running all scenarios

Manage Scenarios... runs a study in every scenario, Base included, from the Run all scenarios buttons:

• Load Flow runs power flow analysis in each scenario. To compare the results, select Compare Scenarios... in the scenario selector.
• Short Circuit and Arc Flash runs both studies in each scenario and keeps the worst case at each bus. See the worst case across scenarios.

The worst case across scenarios

Each bus takes its worst scenario, separately for each purpose:

• Fault duty is the highest fault current at the bus in any scenario, for rating equipment.
• Arc flash takes the scenario with the highest incident energy, not the highest current. A lower current can clear more slowly, so the scenario with less fault current often gives more energy. Every value on that bus's row, from the arcing current and clearing device to the clearing time and its flags, comes from that one scenario.
• A bus with no supply in a scenario is skipped for that scenario. A bus with no supply in every scenario is listed under No supply.
• A bus without a result in any other scenario has no worst case, because the missing one could be the worst. The bus names that scenario and why.

To see it, open Arc flash results from the Arc Flash button's menu and choose Worst case at the top. The table adds a Scenario column naming the scenario behind each bus and a Duty column with the highest fault current and its scenario. The switch appears only in a project with scenarios besides Base. You can also run the worst case from there with Run all scenarios.

The worst case is saved with the project. It is marked out of date when anything it used changes: an edit to the drawing, an override in any scenario, or adding or deleting a scenario. Click Run again in the results window, or Short Circuit and Arc Flash in Manage Scenarios..., to update it. If a scenario cannot run, for example because of a voltage conflict only that scenario has, the other scenarios still run, and the results window names the scenario to fix instead of showing a worst case.

Each scenario's own results stay available: choose the scenario's name at the top of the results window, or switch to the scenario.

Deleting scenarios

To remove a scenario:

1. In the scenario selector, select Manage Scenarios....
2. Click the delete button (Delete scenario) on the scenario you want to remove.
3. Click Delete to confirm.

> Note: You cannot delete Base.

Deleting a scenario also removes all of its override records and calculation results.

Best practices

Naming conventions

Use names that describe the operating condition:

Clean up unused scenarios

Delete scenarios that are no longer relevant. This keeps the scenario list manageable and avoids confusion during batch calculations.

Example workflows

Peak vs normal load comparison

1. Start with your baseline representing normal operating conditions.
2. Create a scenario named "Peak Load".
3. Select the "Peak Load" scenario from the scenario selector.
4. Select each load component and increase the active power to peak values.
5. Run power flow for the "Peak Load" scenario and review results.
6. Switch back to the baseline and run power flow.
7. Compare voltage drops, cable loading, and transformer utilization between the two conditions.
8. Alternatively, use Run All Scenarios to calculate both at once.

Generator offline contingency study

1. Create a scenario named "Generator 1 Offline".
2. Select the scenario from the scenario selector.
3. Select Generator 1 on the canvas and set in_service to false.
4. Run power flow analysis.
5. Check whether the remaining sources can serve all loads.
6. Review bus voltages and branch loading for overload conditions.
7. Repeat for each generator to identify critical contingencies.

Utility fault cases

Enter a utility's fault cases on the utility itself, not as scenarios. One study run evaluates every case included in it. See Fault cases.

If an older project has a scenario such as "Utility normal" that only changes the utility's fault values, move it into a fault case:

1. Switch to the base design and select the utility.
2. On the Study tab, click Add case and name the case after the scenario.
3. Type the scenario's values into the new case's column.
4. Choose the case's studies in the Studies row.
5. Delete the scenario.

A scenario can still change a utility's cases, for example to study a different supply arrangement. The added cases are overridden together, so the reset button beside them returns all of them to the base design. Switching the utility's input method in a scenario converts every case; the reset button beside the method tabs returns the method and the cases to the base design.

Related topics

• Running power flow - Running power flow calculations
• Running short-circuit analysis - Running fault studies
• Running an arc flash study - Reading arc flash results, including the worst case
• Pre-analysis validation - Issues shown before a study runs