Causes and treatment methods of inverter tripping fault

One. Power failure handling
If the power supply is temporarily powered off or the voltage is low, the “undervoltage” display, or the “overvoltage” display of this transient overvoltage may cause the inverter to trip and stop. Generally, the power can be restarted after the power supply returns to normal.
2. External fault handling
If the input signal is open, the output line is open circuit, phase failure, short circuit, grounding or insulation resistance is very low, the motor is faulty or overloaded, etc., the inverter will display “external” fault and trip and stop. After the fault is eliminated, it can be re-enabled.
three. Internal fault handling
If the internal fan is open or overheated, the fuse is open, the device is overheated, the memory is faulty, the CPU is faulty, etc., it can be switched to the power frequency operation without affecting the production. After the internal fault is eliminated, the inverter operation can be resumed.

In the event of an internal fault in the inverter unit, if it is within the warranty period, the manufacturer or the manufacturer’s agent should be notified as soon as possible to be responsible for the warranty. Perform the following checks based on the category and data displayed by the fault:

1. After opening the chassis, first check whether there are any broken wires, solder joints, burnt smells or deterioration of the components inside, if necessary, do the corresponding treatment in time.

2. Use a multimeter to check the resistance of the resistor and the on-off resistance of the diode, switch tube and module to determine whether to break or break down. If yes, replace it with the original nominal value and the withstand voltage value, or replace it with the same type.

3. Use the dual trace oscilloscope to detect the waveform of each working point, and use the step-by-step elimination method to judge the fault location and components.

Issues to be aware of during maintenance:

1. Strictly prevent false soldering, virtual connection, or wrong soldering, continuous soldering, or miswired, especially do not mistakenly connect the power cable to the output.

2. Power-on static check indicator, digital tube and display are normal, and the preset data is appropriate.

3. If there are conditions, a small motor can be used for the simulation dynamic test.

4. With load test.

four. Improper handling of function parameters
When the parameters are preset, the no-load test is normal. If an “overcurrent” trip occurs after loading, the starting torque setting may be insufficient or the acceleration time may be insufficient. Some may also decrease the moment of inertia after running for a period of time, resulting in “overvoltage” during deceleration. “Trip, generally modify the function parameters and then increase the acceleration time to solve.

Distinction of three-phase voltage imbalance

  There are many reasons for the three-phase voltage imbalance, such as single-phase grounding, disconnection resonance, etc., the operation manager can only process it correctly if it is correctly distinguished.

I. Broken wire fault If one phase is disconnected but not grounded, or the circuit breaker and the isolating switch are not connected, the voltage transformer fuse is blown and the three-phase parameters are asymmetrical. When the previous voltage level line is disconnected, the voltage of the next voltage level shows that the three phase voltages are reduced, one of the phases is lower, and the other two phases are higher but the voltage values ​​of the two are close. When the line of this stage is disconnected, the voltage of the disconnected phase is zero, and the voltage of the unbroken phase is still the phase voltage.

2. Ground fault When the line is disconnected and single-phase grounded, although the three-phase voltage is unbalanced, the voltage value after grounding does not change. Single-phase grounding is divided into metallic grounding and non-metallic grounding. Metal grounding, fault phase voltage is zero or close to zero, non-fault phase voltage rises 1.732 times, and lasts forever; non-metallic grounding, ground phase voltage is not zero but decreases to a certain value, the other two phases rise It is less than 1.732 times higher.

Causes of resonance With the rapid development of industry, the nonlinear power load has increased a lot, and some loads not only generate harmonics, but also cause fluctuations and flicker of the supply voltage, and even cause three-phase voltage imbalance.
There are two kinds of three-phase voltage imbalance caused by resonance.

One is the fundamental frequency resonance, the characteristic is similar to single-phase grounding, that is, the voltage of one phase is lowered, and the voltage of the other two phases is increased. It is difficult to find the fault point when looking for the cause of the fault. At this time, the special user can be checked. If it is not grounding, it may be Caused by resonance.

The other is frequency-divided resonance or high-frequency resonance, characterized by a simultaneous increase in three-phase voltage.

In addition, it should be noted that when the air-drop busbar cut-off part line or single-phase ground fault disappears, if a grounding signal occurs, and the one-phase, two-phase or three-phase voltage exceeds the line voltage, the voltmeter pointer hits the head and moves slowly at the same time, or The three-phase voltage alternately rises above the line voltage. In this case, it is generally caused by resonance.
The harm and impact of three-phase imbalance

Harm to the transformer. In the production and living power, when the three-phase load is unbalanced, the transformer is in an asymmetrical operating state. Increased transformer losses (including no-load losses and load losses). According to the transformer operating regulations, the neutral current of the transformer in operation shall not exceed 25% of the rated current of the low-voltage side of the transformer. In addition, the unbalanced operation of the three-phase load will cause the zero-sequence current of the transformer to be too large, and the temperature rise of the local metal parts may even cause the transformer to burn out.

The impact on electrical equipment. The occurrence of a three-phase voltage imbalance will result in several times the current imbalance. The reverse torque is increased in the induction motor, so that the temperature of the motor rises, the efficiency decreases, the energy consumption increases, vibration occurs, and output loss is affected. The imbalance between the phases can lead to shortened service life of the electrical equipment, accelerate the frequency of equipment component replacement, and increase the cost of equipment maintenance. The circuit breaker allows the current margin to decrease, and overload and short circuit are likely to occur when the load changes or alternates. An excessively large unbalanced current flows into the neutral line, causing the neutral line to thicken.

The effect on line loss. Three-phase four-wire system connection method, when the three-phase load balances, the line loss is the smallest; when the one-phase load is heavy, the two-phase load is light, the line loss increment is small; when the one-phase load is heavy, the one-phase load is light, When the load of the third phase is the average load, the line loss increment is large; when the phase load is light, and the load of the two phases is heavy, the line loss increment is the largest. When the three-phase load is unbalanced, the current imbalance is greater and the line loss increment is larger regardless of the load distribution.

How inverter works on air compressor

The use of the frequency converter in the air compressor system is precisely to enable the air compressor system to accurately control the electrical control and frequency conversion control, and immediately control the air compressor motor torque (ie, the ability to drag the load) without changing the air compressor motor torque. The motor speed (ie, output power) responds to system pressure changes by changing the compressor speed and maintains a stable system pressure (setpoint) to achieve on-demand output of high quality compressed air. When the air consumption of the system decreases, the compressed air provided by the compressor is greater than the system consumption. The compressor will reduce the speed and reduce the output compressed air volume; otherwise, it will increase the motor speed and increase the compressed air volume to maintain a stable system pressure value. . The function of the frequency converter in its system is the same as the power saving of the fan motor water pump. According to the load change, the frequency of the input voltage is controlled.

Its energy-saving principle and effect are as follows:

1. After the inverter is used, the pressure setting of the air compressor can be one point, that is, the minimum pressure that meets the requirements of the production equipment can be set pressure, and the inverter will adjust the speed of the air compressor according to the fluctuation of the pipe network pressure. The speed of the air compressor even eliminates the unloading operation of the air compressor and saves energy.

2. Because the inverter in the system makes the pipe network down pressure stable, it can reduce or even eliminate the pressure fluctuations, so that all the operating air compressors in the system are operated under a lower pressure that meets the production requirements, reducing the pressure. Power loss caused by upward fluctuations.

3, because the air compressor can not rule out the possibility of long-term operation under full load, it can only determine the capacity of the motor according to the maximum demand, so the design capacity is generally larger. In actual operation, the proportion of light-load operation time is very high. If frequency conversion speed regulation is adopted, the operating efficiency during operation can be greatly improved. Therefore, the inverter has a great potential for energy saving in the air compressor system.

4, some adjustment methods (such as adjusting the valve opening and changing the angle of the blade, etc.), even in the case of a small amount of demand, it can not reduce the operating power of the motor. After adopting the frequency conversion and speed regulation, when the demand is small, the rotation speed of the motor can be reduced and the operating power of the motor can be reduced, thereby further achieving energy saving.

5, single-motor drive system can not be continuously adjusted according to the severity of the load. The use of variable frequency speed regulation, it can be very convenient for continuous adjustment, can maintain the stability of pressure, flow, temperature and other parameters, thereby greatly improving the performance of the compressor.

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