CSD Series Variable Frequency AC Drive
MOTORTRONICS
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Chapter 9 - Reference
9.1 Measurement of Voltage and Current
The procedure for measuring Primary and Secondary voltage and current will
be somewhat different for VFD's because of the variety of measuring
instruments and high harmonic content of the waveform. Refer to the following
illustration for measurement techniques.
Figure 9-1 - Measuring Volage and Current
9.2 Electromagnetic Compatibility of AC Drives
Similar to all modern PWM variable speed drives the CSD Series AC Drives
uses fast switching of high voltage and currents to achieve high efficiency
and reduced motor acoustic noise. This results in electromagnetic interference
(EMI) and radio frequency interference (RFI) that occurs at the switching
frequency and harmonics of this frequency. The amount of interference is
dependent on the amount of current the drive delivers to the load. For
operational reasons the interference may need to be suppressed. As EMI
and RFI can involve very complex coupling modes, not all solutions can be
easily found.
• Practical solutions include:
• Mounting sensitive equipment at a distance from the drives.
• Providing screening and grounding on all cables, the drive motor
and enclosure.
• Putting filters on the input and output sides of the drive.
Table 9 A - Testing for Voltage and Current
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