Delta Electronics AC Motor Drive VFD-VE Series User Manual

Contents

Delta Electronics AC Motor Drive VFD-VE Series User Manual Manual pdf 284 page image

Revision August 2008, 03VE, SW V2.04 C-1Appendix C How to Select the Right AC Motor DriveThe choice of the right AC motor drive for the application is very important and has great influenceon its lifetime. If the capacity of AC motor drive is too large, it cannot offer complete protection to themotor and motor maybe damaged. If the capacity of AC motor drive is too small, it cannot offer therequired performance and the AC motor drive maybe damaged due to overloading.But by simply selecting the AC motor drive of the same capacity as the motor, user applicationrequirements cannot be met completely. Therefore, a designer should consider all the conditions,including load type, load speed, load characteristic, operation method, rated output, rated speed,power and the change of load capacity. The following table lists the factors you need to consider,depending on your requirements.Related SpecificationItem Speed andtorquecharacteristicsTimeratingsOverloadcapacityStartingtorqueLoad typeFriction load and weightloadLiquid (viscous) loadInertia loadLoad with powertransmission● ●Load speed andtorquecharacteristicsConstant torqueConstant outputDecreasing torqueDecreasing output● ●LoadcharacteristicsConstant loadShock loadRepetitive loadHigh starting torqueLow starting torque● ● ● ●Continuous operation, Short-time operationLong-time operation at medium/low speeds ● ●Maximum output current (instantaneous)Constant output current (continuous) ● ●Maximum frequency, Base frequency ●Power supply transformer capacity orpercentage impedanceVoltage fluctuations and unbalanceNumber of phases, single phase protectionFrequency● ●Mechanical friction, losses in wiring ● ●Duty cycle modification ●C.1 Capacity Formulas