STEP ET Series - Precautions; Motor Insulation Inspection; Thermal Protection of the Motor; About Motor Heat and Noise

Chapter 1 Safety Instructions
Shanghai Sigriner STEP Electric Co., Ltd.
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1.3 Precautions
1.3.1 Motor insulation inspection
Motor insulation inspection should be carried out when the motor is used for the first time, used
again after a long period of time, and regularly inspected to prevent the inverter from being damaged
due to insulation failure of the motor winding. Insulation inspection must be done to separate the
motor connection from the inverter, and it is recommended to use 500V voltage megohmmeter,
which should ensure that the measured insulation resistance is not less than 5MΩ.
1.3.2 Thermal protection of the motor
If the selected motor does not match with the rated capacity of the intelligent flexible driver,
especially when the rated power of the inverter is greater than that of the motor, be sure to adjust the
motor protection related parameter values of intelligent flexible driver or install a thermal relay in
front of the motor to protect the motor.
1.3.3 About motor heat and noise
Since the output voltage of inverter is PWM wave, it contains certain harmonics, so the temperature
rise, noise and vibration of the motor will be slightly increased compared with the working
frequency operation.
When the inverter drives a normal motor at low speed for a long time, the heat dissipation of the
motor becomes worse and the motor temperature increases. If the device needs to run at low speed
with constant torque for a long time, you must use inverter motor or use forced air cooling.
1.3.4 Attention for input and output
Output of intelligent flexible driver is PWM wave. If the output side is installed with capacitor for
improving power factor or varistor for lightning protection, it is easy to trigger instantaneous
overcurrent of inverter or even damage the inverter. Please do not use them.
The diagram of the output side of the inverter must not be connected with capacitors is shown in
Figure 1-1.
V
U
W
M
Fig. 1-1 The output side of the inverter must not be connected with capacitors
If a contactor is installed between the power supply and the input of the inverter, it is not allowed to
use this contactor to control the start/stop of the inverter.
If contactors or other switching devices are installed between the output side and the motor, it should
be ensured that the inverter is operated on and off when there is no output, and it is not allowed to
open/close the contactor when the inverter is outputting, otherwise it may cause damage to the
module.
It is desirable to control the start/stop of the inverter through the terminal. It is strictly forbidden to
use contactors or other switching devices on the input side of the inverter for direct, frequent starting
and stopping, otherwise it will damage the equipment.
1.3.5 When used beyond the rated voltage
If the intelligent flexible driver is used when the external voltage is not within the allowable working
voltage range specified in this manual, it is easy to cause damage to the inverter components. If