User manual

Donotstartthemotormorethanfourtove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 name-

plate 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 opera-

tion. 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 100 feet

a DV/DT output lter is recommended to avoid damage to the motor.

100 feet distance is based on our eld experience, the VFD manufac-

ture may state different distances and distance does vary depending

on the VFD manufacture.

• Program the VFD for variable torque output. Flux vector and constant

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 energy

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 speeds. To beneﬁt

from these advantages, it is important that the drive be installed correctly.

Marley supplies VFD and VFD controls specically designed for our cool-

ing products. If you have purchased a Marley VFD and/or controls package,

please follow the instructions in the User Manual for that system. Most VFD

problems can be avoided by purchasing the Marley drive system. If you are

installing a VFD other than the Marley drive, please refer to that drives instal-

lation manual.

Installation

Warning

Note