26
Application to Motors
[Application to general-purpose motors]
Notes on Use
[Drive]
[Application to special motors]
[Application to the 400V-class motor]
[Installation location and operating environment]
Operating frequency
The overspeed endurance of a general-purpose motor is 120% of the rated speed for 2 minutes (JIS C4,004). For operation at higher than 60Hz,
it is required to examine the allowable torque of the motor, useful life of bearings, noise, vibration, etc. In this case, be sure to consult the motor
manufacturer as the maximum allowable rpm differs depending on the motor capacity, etc.
Torque characteristics
The torque characteristics of driving a general-purpose motor with an inverter differ from those of driving it using commercial power (starting torque
decreases in particular). Carefully check the load torque characteristic of a connected machine and the driving torque characteristic of the motor.
Motor loss and
temperature increase
An inverter-driven general-purpose motor heats up quickly at lower speeds. Consequently, the continuous torque level (output) will decrease at
lower motor speeds. Carefully check the torque characteristics vs speed range requirements.
Noise
When run by an inverter, a general-purpose motor generates noise slightly greater than with commercial power.
Vibration
When run by an inverter at variable speeds, the motor may generate vibration, especially because of (a) unbalance of the rotor including a
connected machine, or (b) resonance caused by the natural vibration frequency of a mechanical system. Particularly, be careful of (b) when
operating at variable speeds a machine previously fitted with a constant speed motor. Vibration can be minimized by (1) avoiding resonance points
using the frequency jump function of the inverter, (2) using a tire-shaped coupling, or (3) placing a rubber shock absorber beneath the motor base.
Power transmission
mechanism
Under continued, low-speed operation, oil lubrication can deteriorate in a power transmission mechanism with an oil-type gear box (gear motor)
or reducer. Check with the motor manufacturer for the permissible range of continuous speed. To operate at more than 60 Hz, confirm the
machine’s ability to withstand the centrifugal force generated.
Run / Stop
Run or stop of the inverter must be done with the keys on the operator panel or through the control circuit terminals.
Do not operate by installing a electromagnetic contactor (Mg) in the main circuit.
Emergency motor stop
When the protective function is operating or the power supply stops, the motor enters the free run stop state.
When an emergency stop is required or when the motor should be kept stopped, use of a mechanical brake should be considered.
High-frequency run
A max. 400 Hz can be selected on the WJ200 Series. However, a two-pole motor can attain up to approx. 24,000 rpm, which is extremely dangerous.
Therefore, carefully make selection and settings by checking the mechanical strength of the motor and connected machines. Consult the motor
manufacturer when it is necessary to drive a standard (general-purpose) motor above 60 Hz. A full line of high-speed motors is available from Hitachi.
Gear motor
The allowable rotation range of continuous drive varies depending on the lubrication method or motor manufacturer.
(Particularly in case of oil lubrication, pay attention to the low frequency range.)
Brake-equipped motor
For use of a brake-equipped motor, be sure to connect the braking power supply from the primary side of the inverter.
Pole-change motor
There are different kinds of pole-change motors (constant output characteristic type, constant torque characteristic type, etc.), with different
rated current values. In motor selection, check the maximum allowable current for each motor of a different pole count. At the time of pole
changing, be sure to stop the motor. Also see: Application to the 400V-class motor.
Submersible motor
The rated current of a submersible motor is significantly larger than that of the general-purpose motor. In inverter selection, be sure to check the
rated current of the motor.
Explosion-proof motor
Inverter drive is not suitable for a safety-enhanced explosion-proof type motor. The inverter should be used in combination with a pressure-proof
explosion-proof type of motor. *Explosion-proof verification is not available for WJ200 Series.
Synchronous (MS) motor
High-speed (HFM) motor
In most cases, the synchronous (MS) motor and the high-speed (HFM) motor are designed and manufactured to meet the specifications suitable
for a connected machine. As to proper inverter selection, consult the manufacturer.
Single-phase motor
A single-phase motor is not suitable for variable-speed operation by an inverter drive. Therefore, use a three-phase motor.
A system applying a voltage-type PWM inverter with IGBT may have surge voltage at the motor terminals resulting from the cable constants including the cable length and the cable
laying method. Depending on the surge current magnification, the motor coil insulation may be degraded. In particular, when a 400V-class motor is used, a longer cable is used,
and critical loss can occur, take the following countermeasures: (1) install the LCR filter between the inverter and the motor, (2) install the AC reactor between the inverter and the
motor, or (3) enhance the insulation of the motor coil.
Avoid installation in areas of high temperature, excessive humidity, or where moisture can easily collect, as well as areas that are dusty, subject to corrosive gasses, mist of liquid for grinding,
or salt. Install the inverter away from direct sunlight in a well-ventilated room that is free of vibration. The inverter can be operated in the ambient temperature range from –10 to 50
º
C.
(Carrier frequency and output current must be reduced in the range of 40 to 50
º
C.)
• Before use, be sure to read through the Instruction Manual to insure proper use of the inverter.
• Note that the inverter requires electrical wiring; a trained specialist should carry out the wiring.
• The inverter in this catalog is designed for general industrial applications. For special applications in fields such as aircraft, outer space, nuclear power, electrical power, transport
vehicles, clinics, and underwater equipment, please consult with us in advance.
• For application in a facility where human life is involved or serious losses may occur, make sure to provide safety devices to avoid a serious accident.
• The inverter is intended for use with a three-phase AC motor. For use with a load other than this, please consult with us.
Precaution for Correct Usage
For Correct Operation
Stöwer Antriebstechnik GmbH, Enneststrasse 3, 51702 Bergneustadt, tel: 02261-40970, Fax: 02261-41309
