CHINT NVF5 Series Instruction Manual page 6

Instructions for NVF5 Series Inverters
1 Main Usage Scope of Application
1.1 Main Usage and Scope of Application
Featuring fast load response, large low frequency torque and high overload capacity, the NVF5 series
inverter adopts speed sensorless vector control technology to achieve precise control of various equipment.
With its constant voltage output, torque limitation, rotational speed tracking, simplified PLC and process PID
functions, this product is designed to meet the electrical driving demands of various applications including
wiredrawing, textile, machine tool, papermaking, packaging, food, plastic, fans and pumps, and all kinds of
automatic production equipment.
1.2 Precautions
Precautions
Comparison with
frequency type
operation
Constant torque low
speed operation
Electronic thermal
protection value of
motor
Operate above 50Hz
Lubrication of
mechanical devices
Negative torque load
Mechanical resonance
point of load bearing
device
Frequent start and
stop
Motor insulation
check before
connecting the
inverter
01
Table 1.1 Precautions
This is a voltage type inverter with output voltage of PWM wave which includes a
certain proportion of harmonic. Therefore, temperature rise, noise and vibration
during operation might be slightly bigger than those in frequency type operation.
When the inverter is used to drive the long-term low-speed operation of regular
motors, the output torque limit should be decreased due to the poor heat
dissipation of the motor. If you need to use the inverter for long-term low-speed
operation with constant torque, you must choose a variable frequency motor.
If a matching motor is selected, the inverter can provide thermal protection for the
motor. If the rated capacity of the selected motor does not match with that of the
inverter, make sure to set up a proper protection value or take other protective
measures to guarantee the safe operation of the motor.
If you need to run the product above 50Hz, please pay attention to the increase in
motor vibration and noise; remember to check the speed range of motor bearings
and mechanical devices first.
The lubrication effect of mechanical devices such as reduction gearbox and gear will
reduce over long-term low-speed operation, which may lead to equipment damage;
please check the lubrication in advance.
Negative torque often occurs in applications where load increase is needed, which
makes inverter to trip due to overcurrent or overvoltage. In such case, user should
use braking components with proper parameters.
The input frequency range of the inverter may include the mechanical resonance
point of load bearing device. In such case, user must set up a hopping frequency to
bypass the mechanical resonance point.
Use terminals to control the start and stop of inverter. It is prohibited to use
switching devices such as contactor for frequent start and stop operations at the
input side of the inverter, otherwise the equipment can be damaged.
Before using the motor for the first time or after long-term idle, check the insulation
of the motor so that the inverter will not be damaged due to invalid insulation of
motor winding. See the figure for wiring. Use 500V voltage type megameter for
measurement. The insulation resistance should not be smaller than 5MΩ.
Motor cable
Motor
terminals
UVW
Grounding
Megger
Explanations