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Frequently Asked Questions

Getting Started

Q.Why doesn’t the motor have a neutral connection as a return to the inverter?

A.The motor theoretically represents a “balanced Y” load if all three stator windings have the same impedance. The Y connection allows each of the three wires to alternately serve as input or return on alternate half-cycles.

Q.Does the motor need a chassis ground connection?

A.Yes, for several reasons. Most importantly, this provides protection in the event of a short in the motor that puts a hazardous voltage on its housing. Secondly, motors exhibit leakage currents that increase with aging. Lastly, a grounded chassis generally emits less electrical noise than an ungrounded one.

Q.What type of motor is compatible with the Hitachi inverters?

A.Motor type – It must be a three-phase AC induction motor. Use an inverter- grade motor that has 800V insulation for 200V class inverters, or 1600V insulation for 400V class.

Motor size – In practice, it’s better to find the right size motor for your application; then look for the inverter to match the motor.

NOTE: There may be other factors that will affect motor selection, including heat dissi- pation, motor operating speed profile, enclosure type, and cooling method.

Q.How many poles should the motor have?

A.Hitachi inverters can be configured to operate motors with 2, 4, 6, or 8 poles. The greater the number of poles, the slower the top motor speed will be, but it will have higher torque at the base speed.

Q.Will I be able to add dynamic (resistive) braking to my Hitachi L200 drive after the initial installation?

A.Yes. The L200 inverter already has a dynamic braking circuit built in. Just add the resistor sized to meet the braking requirements. For more informa- tion, contact your nearest Hitachi representative.