Motor should have hIgh electrical efficiency, less differential between maximum and minimum torque verses speed curve, lock rotor no less than 135% unless a fluid coupling or inverter are used.

You should understand the torque path required of fluid couplings so that the fluid coupling pump curve covers the motor torque curve.

Both soft-start devices can use a lower locked-rotor torque than even 100% lock-rotor which can improve electrical efficiency construction techniques.

Care must be taken with inverters that the voltage differential of shaft to frame/housing will not cause bearing pitting. A special brass brush or similar grounding method is typically required.

Good rotor cooling, strong end windings and a thermal rating of Class B temperature rise and class F insulation should be standard and typical to NEMA ratings.

Read the CEMA manual for some tips. ■

In addition, the bearing rating should exceed 60,000 and preferrably 100,000 L-10 life hours.

Include manufacturing provision for installing a accurate speed sensor. Be novel and use a optical encoder within the housing.

Include provisions for RTD's to offer thermal rise protection and have multiple probes. Typically 6 are requred.

Read the literature of other manufacturers that wish to sell to the material handling industry such as: WEG, Siemens, ABB, GE, Yasakawa, ....

Provide good lubrication of bearings and know how to protect against sliding with bigger drives such as jack shaft high pressure (1500 psi) lubrication.

Provide low voltage to motor sizes above 300 kW and medium and high voltage rating to motor sizes below 300 kW. Typical voltage ranges include: 480, 600, 3300, 4160 and 6600. Read the literature of others. There are differing standards for underground and above ground, hazardous environments, open frame and totally enclosed frames, tube cooling, etc.

Can your motors have a flywheel installed between the bearings? This means the drive shaft will need to be enlarged.

Know the difference between copper and aluminum constructions and their benefits.

Can you provide drive inertias, and designs for 60 hz, 50 hz, 4 pole, 6 pole, and 8 pole construction?

Provide superior frame cooling methods and publish surface area benefits of your design. Select a good sun-reflective paint color to minimize temperature extremes in high sunlight environment.

There are many more details that need to be considered. I offer but a few. ■