PowerFlex 755 Install Manual.pdf

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Motor Considerations
Input Power Conditioning
Certain events on the power system supplying a drive can cause component
damage or shortened product life. These conditions are divided into 2 basic
categories:
1. All drives
– The power system has power factor correction capacitors switch in
and out of the system, either by the user or by the power company.
– The power source has intermittent voltage spikes in excess of 6000
volts. These spikes could be caused by other equipment on the line or
by events such as lightning strikes.
– The power source has frequent interruptions.
2. 5 Hp or Less Drives (in addition to “1” above)
– The supply transformer is larger than 100 kVA or the available short
circuit (fault) current is greater than 100,000A.
– The impedance on the input side of the drive is less than 0.5%.
If any of these conditions exist, additional source impedance is required.
The total input impedance is a function of all transformers, cabling, and
reactors (if used) that supply power to the drive. The impedance can be
calculated using the information supplied in Wiring and Grounding
Guidelines for PWM AC Drives, publication DRIVES-IN001.
Due to the operational characteristics of AC variable frequency drives,
motors with inverter grade insulation systems designed to meet or exceed
NEMA MG1 Part 31.40.4.2 standards for resistance to spikes of 1600 volts
are recommended.
Guidelines must be followed when using non-inverter grade motors to avoid
premature motor failures. Refer to Wiring and Grounding Guidelines for
Pulse Width Modulated (PWM) AC Drives, publication DRIVES-IN001 for
recommendations.
PowerFlex 750-Series Installation Instructions – Publication 750-IN001C-EN-P – September 2009