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Troubleshooting of Overload Trip of Inverter of Blow Molding Machine

2022-06-11 Hits: 43 views

The overload trip of the blow molding machine inverter is one of the common problems during the operation of the blow molding machine.
The overload trip of the inverter should be handled by scientific and effective methods.
This article will detail the causes and solutions for inverter overload trips.

What is the overload of blow molding machine inverter?
The motor can turn, but the running current exceeds the rated value, which is called overload. The basic reflection of overload is that although the current exceeds the rated value, it does not greatly exceed the rated value, and generally does not form a large inrush current.

What is the reason for the overload trip of the blow molding machine inverter?

Mainly for 3 reasons

1. Wrong behavior
The current detection part of the inverter is faulty, and the detected current signal is too large, resulting in tripping.

2. Large mechanical load
The main characteristic of overload is motor heating, which can be found by reading the running current from the display.

3. The unbalanced three-phase voltage causes a certain phase operating current to be too large, resulting in overload tripping.
It is characterized by uneven heating of the motor, which may not be found when reading the running current from the display (because the display shows only one phase current).

To find the reason, we must think about the way to deal with the overload of the inverter.

How to deal with overload trip of blow molding machine inverter?

1. Check whether the three-phase voltage on the motor side is balanced.
If the three-phase voltage on the motor side is unbalanced, the three-phase voltage on the output side of the inverter should be checked again, if it is also unbalanced, the problem is inside the inverter. The inverter module and drive circuit of the inverter should be checked.
If the voltage output from the inverter is balanced, the problem is in the circuit between the inverter and the motor, check that all terminal bolts are tightened.
If there is a contactor or other electrical appliances between the inverter and the motor, check whether the wiring terminals of the related electrical appliances are tightened and the contact state of the contacts is good.

If the three-phase voltages on the motor side are balanced, the operating frequency during the trip should be known.
If the operating frequency is low and there is no vector control (or no vector control), first reduce the U/F ratio. If the load can still be driven after the reduction, it means that the preset U/F ratio is too high and the peak value of the excitation current is too large. The current can be reduced by lowering the U/F ratio.
If the decrement is performed with a fixed load, the capacity of the inverter should be considered, and if the inverter has a vector control function, the vector control method should be adopted.

2. Checking whether the motor is hot
If the temperature rise of the motor is not high, you should first check whether the preset value of the electronic thermal protection function of the inverter is reasonable. If the inverter still has space, you should relax the preset value of the electronic thermal protection function. There is no need to relax any more. According to the required production process, the overload phenomenon that occurs is a normal overload, indicating that the inverter is not properly selected. The capacity of the inverter should be increased and the inverter should be replaced.

When the motor is driving a variable load or intermittent load, as long as the temperature rise does not exceed the rated value, overload in a short time (minutes or tens of minutes) is allowed, but the inverter cannot. If the temperature rise of the motor is too high, and the overload is normal overload, it means that the motor is overloaded. At this time, the transmission ratio should be appropriately increased to reduce the load on the motor shaft. If possible, the transmission ratio should be increased. If the transmission ratio cannot be increased, the capacity of the motor should be increased.

3. Check for malfunction
If there is no problem with the above checks, check whether it is malfunctioning. The method of checking is to measure the output current of the inverter with an ammeter under light load or no load, and compare it with the running current value displayed on the display. If the current reading displayed on the display is much larger than the actual current, it means that the inverter The current measurement part inside the device has a large error, and the “overload” trip may be a malfunction.

The reasons for the overload trip of the blow molding machine inverter and the treatment methods are here. This is when the blow molding machine inverter overloads and trips, the problem will be quickly and effectively solved by following above steps.