YASKAWA VS MINI J7 Specifications download pdf (Page 33)

VS mini J7

NOTES ON USE (Cont'd)

Motor

When gear boxes and change/reduction gears lubricated with oil are used in

power transmission systems, continuous low speed operation decreases the oil

lubrication function. Also, operation at more than 60Hz may result in noise,

reduced life, etc.

Synchronous Motors

Contact your YASKAWA representative for selecting inverter since starting current and rated current is larger

than those of standard motor. Be careful when several motors are turned ON and OFF individually at group

control. They may step out.

Select the inverter with a capacity exceeding the rated current of each pole. Pole change should be made

only after the motor stops.

If a pole changed while the motor is rotating, the regenerative overvoltage or overcurrent protection circuit is

activated and the motor coasts to a stop.

Since the rated current of underwater motors is large compared with general purpose motors, select an

inverter with a larger capacity. If the wire length between the inverter and the motor is large, use cables with

sufficiently large diameter.

Explosion-proof motors which are applied to an inverter must be approved as explosion-proof equipment.

The inverter is not explosion-proof and should not be located where explosive gases exist.

Lubrication method and continuous rotation limit differ with manufacturers. When oil lubrication is employed,

continuous operation only in low speed range may cause burnout. Before operating the motor at more than

60Hz you should consult the motor manufacturer.

Single-phase motors are not suitable for variable speed operation with an inverter. If the inverter is applied to

a motor using a capacitor stack, a high harmonic current flows and the capacitor may be damaged. For

split-phase start motors and repulsion start motors, the internal centrifugal switch will not be actuated and the

starting coil may be burnd out. Therefore, use only 3-phase motors.

Pole Change Motors

Submersible Motors

Explosion-proof Motors

Geared Motors

Single-phase Motors

36 20

FREQUENCY (Hz)

60% ED (OR 40 MIN)

40% ED (OR 20 MIN)

25% ED (OR 15 MIN)

TORQUE

(%)

100

Allowable Load Characteristics

of a Standard Motor

CONTINUOUS

Application for Existing Standard Motors

A standard motor driven by the inverter generates slightly less power than it

does when it is driven with commercial power supply.

Also, the cooling effect deteriorates in low speed range so that the motor

temperature rise increases. Reduce load torque in the low speed range.

Allowable load characteristics of the standard motor are shown in the figure.

If 100% continuous torque is required in the low speed range, use an inverter

duty motor.

Also, if input voltage is high (440V or more) or wiring distance is long,

consider the withstand voltage of the motor. For details, contact your

YASKAWA representative.

When the motor is used above 60Hz, the motor mechanical design should be verified. Contact your motor manufacturer.

< High speed operation

Motor torque characteristics vary when the motor is driven by an inverter instead of commercial power supply. Check the load torque characteristics of

the machine to be connected.

< Torque characteristics

Because of the high carrier modulation technique for PWM control, the VS mini J7 reduces motor vibration to a level equal to running with a

commercial power supply. Larger vibrations may occur under the following conditions:

•

Response at resonant frequency of the mechanical system.

Special care is required if a machine which has previously been driven at a constant speed, is to be driven at varying speeds. Installation of

antivibration rubber padding under the motor base and prohibited frequency control are recommended.

•

Rotator residual imbalance

Special care is required for operation at frequencies higher than 60Hz.

< Vibration

Inverter operation is as quiet as operation with commercial power supply: At above rated speed (60Hz), noise may increase by motor cooling fan.

< Noise

Application for Special Purpose Motors

Power Transmission Mechanism (Gear Reduction, Belt, Chain, etc.)

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YASKAWA VS MINI J7 Specifications Page 33

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