Impact of VSDs

[Boerewors]

Hi all,

I am doing an investigation on the impact of variable speed drives (VSDs) on motor lifetime (LV only). This investigation could be extended to include pros and cons of installing VSDs as opposed to using DOL starters.

Any information or suggestions that could help me get started?

Thank you in advance
Worsie

 

[jbartos]

Suggestion: Visit

http://www.oit.doe.gov/bestpractices/pdfs/biblio.pdf

for:
1.
Brithinee, Wallace P., “Electric Motor Maintenance & Repair for Long-Term Efficiency.” Energy Engineering, Vol. 95, No. 1, 1998, p. 22-30.
Focuses on three-phase electric motor maintenance and repair issues, with comments on the interaction with electronic drives.
2.
Falkner, Hugh, “Drive for more efficient motors.” Metallurgia, Vol. 64, April 1997 supplement, p. S4-S5.
Discusses recent changes in the energ y - e fficient motor market, and re p a i r / replace options.
3.
Litman, Todd, Efficient Electric Motor Systems Handbook, Fairmont Press, 1995.
Discusses the typical kinds of problems that lead to motor inefficiency or failure. Also discusses how to determine when it makes economic sense to upgrade to an energy-efficient motor, and whether an adjustable speed drive or other advanced control system will give you the results you seek. It covers all aspects of motor systems including motor repairs, and predictive & preventive maintenance. Nine useful appendices are included, such as a procedure for
motor repair shop evaluation, model electric motor repair specifications, and forms and checklists for tracking a motor through a quality repair.
4.
P e n rose, Howard W., “Electric motor repair for low voltage induction motors in PWM invert e r duty environments." P roceedings of the 1997 23rd IEEE
E l e c t r i c a l / E l e c t ronics Insulation Conference and Electrical Manufacturing & Coil Winding Confere n c e, Rosemont, IL, 1997, p 841-848.
Presents a recommended repair specification meant to reduce the chance of inverter duty failure with VFD-driven motors.
5.

 

[dpc]

Check NEMA website for "Application Guide for AC Adjustable-Speed Drive Systems". It used to be available free in .pdf format.

I'd also check with motor suppliers such as Toshiba and US Motors for information on their websites.

Your question has a lot of variables to deal with. "Inverter-Duty" motors can be purchased that should, in theory, have a longer life than a normal motor in AFD service. The cable length from the drive to the motor can have a large impact on the voltage transients seen at the motor. The type of drive may also have a significant impact.

My initial thought is that motor life would not be significant factor in determining a selection between an AFD and a constant-speed motor.