How to Troubleshoot VFD Output with Low-Pass Filtering

+ Portable Multimeter

Measure VFD Output Correctly

Variable frequency drives improve motor efficiency by adjusting output voltage and frequency to match load demand, but their output is not a pure sine wave. Instead, the drive generates a PWM-based waveform with high-frequency switching components that can complicate AC voltage measurements and make troubleshooting results harder to interpret accurately.

When technicians measure VFD output with a standard meter setup, switching content can distort the displayed reading and obscure the fundamental output. A measurement approach that reduces unwanted high-frequency content helps produce more reliable results, improves troubleshooting confidence, and supports more accurate maintenance and diagnostic decisions in the field.

Low-Pass VFD Troubleshooting Solution

Troubleshooting AC voltage on variable frequency drive (VFD) outputs can be difficult because high-frequency switching content can distort the reading and make the fundamental output harder to interpret. Keysight addresses this challenge with portable multimeters designed for industrial electrical troubleshooting, including low-pass filtering to suppress unwanted pulse-width modulation (PWM) noise during AC voltage checks. This helps technicians capture readings that better reflect actual drive output conditions. In demanding motor-drive environments, more accurate measurement can speed fault isolation, improve maintenance confidence, and reduce misinterpretation. Keysight handheld digital multimeters (DMMs) also support field work with rugged construction, IP67 protection, CAT III 1000 V / CAT IV 600 V safety ratings, Vsense, and long battery life.

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