A SERVICE OF

logo

Open as PDF
next previous
9
When using a two-speed starter:
• Motorrotationmustbethesameatslowspeedandhighspeed.
• Singlewindingmotorrequiresastarterwithashortingcontactor.
• Two-winding motor requires a starter without a shorting
contactor.
• Alltwo-speedstartersmusthavea20secondtimedelayrelay
when switching from high speed to low speed.
• Donotstartthemotormorethansix times per hour (each low
speed start and each high speed start count as one start).
When using a VFD:
Before beginning, ensure that the motor is rated for “Inverter Duty”
per NEMA MG-1, part 31.
• Set the VFD solid stateoverload protection to 119% of motor
nameplate amps and set “maximum current parameter” in the
VFDtomotornameplateamps.“Maximumcurrentparameter”will
reduce fan speed and limit amp draw to nameplate amps during
cold weather operation. If furnished with a mechanical O.L. set this
at110%overmotornameplateamps.
• MotorrotationmustbethesameinbothVFDmodeandBy-pass
mode.
• IfcabledistancebetweentheVFDandmotorisgreaterthan31ma
DV/DToutputlterisrecommendedtoavoiddamagetothemotor.
31mdistanceisbasedonoureldexperience,theVFDmanufacture
may state different distances and distance does vary depending
ontheVFDmanufacture.
• ProgramtheVFDforvariabletorqueoutput.Fluxvectorandcon-
stant torque modes may damage the gearbox.
• Donotstartandstopthemotorusingthesafetyswitchatthemotor.
If the drive is being commanded to run and the load side is cycled
ONandOFFwiththesafetyswitchthismaydamagetheVFD.
UsingaVFDincoolingapplicationshasadvantagesovertraditionalsingle
ortwospeedmotorcontrol.AVFDcanreducethecostofelectricalen-
ergy being used and provide better temperature control. In addition, it
reduces the mechanical and electrical stress on the motor and mechanical
equipment. Electrical savings can be large during periods of low ambient
temperature when the cooling requirement can be satisfied at reduced
Installation
Note