Motor starting and voltage dip analysis in Electrisim

Motor Starting checks voltage dip and loading when asynchronous motors start. Use the steady-state study for three snapshots (before / locked-rotor / after), or the dynamic study for a time-domain startup. Methods include DOL, soft-start, star-delta, autotransformer, and reactor.

Where to find it: Simulate → Motor Starting. Requires a subscription. Each motor needs locked-rotor current, R/X, and rated voltage in the Motor dialog. Reference: Motor starting in documentation.

When to use

• Voltage dip vs a limit (for example 10–15%) during DOL or soft-start
• Comparing starter methods in steady-state
• Start time and voltage recovery in dynamic mode (ANDES)

How to run

1. Place Motor elements and fill locked-rotor data.
2. Click Simulate → Motor Starting.
3. Choose steady-state or dynamic, the motors to start, and the starter method.
4. Run and review bus dip, branch loading, and (in dynamic mode) the time plots.

Steady-state (pandapower)

1. Before: motors to start are out of service; load flow gives pre-start voltages.
2. During: each starting motor is a locked-rotor PQ load. Starting current scales by method factor (DOL = 1, soft-start from current limit, star-delta = 1/3, autotransformer = tap², reactor from series reactance).
3. After: motors return at their loading; post-start voltages are computed.
4. Checks: dip % vs limit on every bus; branch loading during start vs thermal limit.

Dynamic (ANDES)

Selected motors become dynamic devices; a toggle connects each motor at the start time. Time-domain simulation returns voltage, current, slip, and torque vs time. Soft-start in dynamic mode can approximate an initial current limit by scaling motor Sn.

Run motor starting on the same diagram you use for load flow: app.electrisim.com.

Related: Load flow tutorial, EasyPower alternative (arc flash and motor studies), and full motor starting documentation.