1) The mechanical load is too heavy, its main feature is that the motor is hot, touching the motor shell by hand, which is obviously hot; it can also read the running current from the inverter display screen, compare with the rated current of the motor, and judge the overload situation.
2) Three phase voltage unbalance
The operation current of a certain phase is too large, resulting in overload trip. Its characteristic is that the motor heating is unbalanced, and it may not be found when reading the running current from the display screen (because many inverter displays only one phase current); the effective method is to measure the three-phase output voltage of the inverter with a voltmeter, so as to judge whether the inverter is lack of phase or voltage imbalance.
The internal current detection part of the inverter breaks down, and the detected current signal is too large, resulting in overload trip
Lightning is divided into direct lightning and induction lightning. Direct lightning is the lightning directly falling on the lightning objects, causing the greatest damage; induced lightning is the induced high voltage generated by the electromagnetic wave generated by lightning on the conductor, which makes the electrical appliances connected to the conductor over-voltage and damage.
In the power grid, multi-stage lightning arresters have been installed, but the residual voltage of the former stage lightning or the lightning induced voltage near the inverter will still cause damage to the inverter.
Solution: install lightning arrester in inverter control cabinet.
The incoming line arrester can adopt power lightning protection module, slide installation and parallel grounding. The arrester module is gap discharge, the impulse discharge current is 15kA (10 / 350 μ s), and the working voltage is 250V. It is also possible to use parallel varistor in the power line for lightning protection.
The DBU is a braking unit and requires an external braking resistor. When the motor have regenerative energy, the DBU detects that DC bus voltage rises and consumes the feedback energy on the braking resistor.
RBU is an energy feedback unit. When RBU detects an increase in DC bus voltage, it will feedback energy back to the AC grid instead of dissipating energy to the resistor. When the motor generates feedback energy, DBU or RBU must be selected, otherwise the inverter will report an OV fault.
Effectively suppress the instantaneous high voltage during IGBT switching and increase the effective transmission distance of the inverter.
Reduce surge and peak current, improve power factor, suppress grid harmonics, and improve the effect of input current waveform.
INVT products support AC input or DC input. When the front-end rectifier provides a DC bus, you can connect the + and - terminals of VFD to the DC bus. When the production process requires multiple motors to work together,can adopt the DC common bus solution, some of the motors work in the electric state, and some work in the brake state. At this time, the feedback energy can be directly used in the electric mode motor, can save energy. Common DC bus solution don't need the input circuit breaker of each inverter, can save the costs. It is recommended to add a fuse protection between the bus and the motor.
Please check below steps:
1. IGBT is damaged. Check the drive cable and replace the module;
2. The motor is short circuited to the ground. Please check whether there is a short circuit to the ground and confirm the insulation resistance of the motor;
3. Confirm the correct wiring, and pay special attention not to connect the motor wire to the PE terminal.
The hall wire is not connected well, or the sensor is damaged, or the current detection circuit need to check.
Check that whether the input power supply is lack of phase, the input power terminal is loose, and the input power supply voltage fluctuates greatly or not. Check whether there is any problem in the rectification and whether the DC voltage is lower than 380V.