Application note - Impedance Measurement of a Three‑Phase Motor

Thu 23.07.2026

Accurate measurement of winding impedance and neutral-to-housing capacitance in a three‑phase asynchronous motor is essential for fault detection, failure prevention, and ensuring optimal performance and safety. This guide demonstrates the setup and calibration procedure using the Bode 100 analyzer, including interpretation of characteristic frequency-dependent behaviors.

Impedance Measurement of a

Three-Phase Motor

This application note provides a detailed methodology for measuring the winding impedance of a three-phase motor. Additionally, it includes procedures for assessing the capacitance between the neutral point and the motor housing.

Understanding the impedance of a three-phase motor can be of importance for maintaining performance and efficiency. Measuring the impedance of the windings can help detect issues such as short circuits, insulation problems, or damage to the windings. Furthermore, the impedance response over frequency provides information on high-frequency behavior of inverter driven motors. High-frequency currents can cause unwanted disturbances (EMI) and losses.

Measuring the capacitance between the neutral point and the motor housing helps keep this capacitance low to maintain proper insulation, prevent current leakage, and protect the motor and connected systems.

Check out the application note below for detailed instructions on setting up the connection and configuring the Bode 100 for accurate impedance measurements on a three-phase motor.

Here is a link for download of "Impedance Measurements of a Three-Phase Motor" Application note