Motor Application Precautions; Precautions For Existing Standard Motors - YASKAWA GA80U4720ABM Manual

Table of Contents

3.18 Motor Application Precautions

Low-Speed Range

When a drive operates a standard motor, it will lose more power compared to operating the motor with a commercial

power supply. In the low speed range, the temperature of the motor increases quickly because the motor cannot

decrease its temperature when the speed decreases. In these conditions, decrease the load torque of the motor in the

low-speed range.

continuous torque is necessary at low speeds, use a motor designed to operate with a drive.

A - 25% ED (or 15 min)

B - 40% ED (or 20 min)

Figure 3.81 Permitted Load Characteristics for a Yaskawa Standard Motors

Insulation Withstand Voltage

Consider motor voltage tolerance levels and motor insulation in applications with an input voltage of over 440 V or

particularly long wiring distances. Use an insulated drive motor.

NOTICE: Use an inverter-duty motor or vector-duty motor with reinforced insulation and windings applicable for use with an AC

drive. If the motor does not have the correct insulation, it can cause a short circuit or ground fault from insulation deterioration.

High-Speed Operation

If you operate a motor more than its rated speed, you can have problems with the motor bearing durability and

dynamic balance of the machine. Contact the motor or machine manufacturer.

Torque Characteristics

When you operate a motor with a drive, the torque characteristics are different than when you operate the motor

directly from line power. Make sure that you know about the load torque characteristics for your application.

Vibrations could occur in the these conditions:

• Resonance with the natural frequency of machinery

Use caution if you add a variable-speed drive to applications that operate the motor from line power at a constant

speed. If resonance occurs, install shock-absorbing rubber around the base of the motor and enable the Jump

frequency control.

• The motor is not balanced

Use caution if the motor speed is more than the rated motor speed.

• Subsynchronous resonance

Subsynchronous resonance can occur with long motor shafts and in applications such as turbines, blowers, and fans

with high inertia loads.

shows the permitted load characteristics for a Yaskawa standard motor. When 100%

C - 60% ED (or 40 min)

D - Continuous operation

YASKAWA SIEPC71061737B GA800 Drive Technical Reference