Motor Drive Input; Voltage And Current - Fluke ScopeMeter 190 Series III User Manual

190 Series III
Users Manual

Motor Drive Input

The Motor Drive Input functions check the drive input conditions. Input voltage relates to the
quality of the mains power that feeds the drive. Input current depends on the loading of the drive
and the condition of the drive input section.

Voltage and Current

Voltage and Current measurements check for supply voltage, current, and frequency at the Motor
Drive input.
The measurement is done on one of the phases and for 3-phase systems can be repeated for the
other phases. Voltage measurements between two phases (Phase-Phase) or between phase
and ground (Phase-Ground) is selected in the submenu.
The display shows the voltage waveform in red and the current waveform in blue. The rms
voltage, rms current and frequency are displayed as readings in the top of the display.
For displayed readings, use 2 to change to the Volt Peak readings or Current Peak
readings: Peak-Peak, Maximum Peak, Minimum Peak as well as the Crest Factor (ratio between
peak and rms value). This only changes the readings. The voltage and current waveform
continue to show on the display with no change.
Tips:
• The test tool can compare the rms voltage against the intended nominal voltage. The Vrms
should be ±10 % of the intended voltage.
• If the voltage is out-of-range:
◦ Check if the local circuit is overloaded.
◦ Check if the load of the circuit matches the current rating of the circuit breaker. A high
current load can result in a low voltage on the drive input.
◦ Check the sizing of the conductor feeding the circuit to see whether the cable size is
within specifications compared to local requirements.
◦ If the voltage is ±10 % of intended voltage, the voltage level is not the problem during the
measurement period. Certain conditions can cause the voltage to go outside of the
acceptable limits during other time periods.
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