Myth 1: Connect electromagnetic switches and electromagnetic touches in the output circuit of the inverter
In practical application, some occasions need to use the touch device for inverter switching: such as switching to the power frequency state when the frequency conversion is faulty, or being elected to use the one-to-two method, one motor is faulty, and the inverter turns to drag another motor. Therefore, many users will think that the installation of electromagnetic switches and electromagnetic touchers in the output circuit of the inverter is a standardized equipment and a way to safely disconnect the power supply, but in fact, there is a greater danger in this practice.
Disadvantages: When the inverter is still working, the toucher is disconnected first, and the load is suddenly aborted, and the inrush current will make the overcurrent maintenance action, which will have a certain impact on the main circuit of the rectifier inverter. Severely, it can even cause damage to the IGBT of the inverter output module. Together, when the rational motor is loaded, the rational magnetic field energy cannot be released quickly, and high voltage will occur, which will damage the insulation of the motor and the connecting cable.
Coping strategy: connect the output side of the inverter directly with the motor cable, and the normal start-stop motor can be completed by triggering the inverter control terminal to achieve the role of soft start and soft stop. If it is necessary to use the touch device on the output side of the frequency conversion governor, it is necessary to carry out the necessary control interlock between the output of the frequency conversion governor and the action of the touch device, so as to ensure that the touch device can only operate when the frequency conversion governor has no output.
Myth 2: When the equipment is out of operation normally, disconnect the inverter to communicate with the input power
When the equipment is normally out of operation, many users are accustomed to disconnecting the inverter to communicate with the input power switch, thinking that it is safer and can save energy.
Disadvantage: This approach seems to be able to maintain the inverter from the impact of power failure. In fact, the inverter is not charged for a long time, coupled with the influence of on-site environmental humidity, which will cause the internal circuit board to be slowly oxidized and gradually short-circuited. This is the reason why after the inverter is out of power and out of operation for a period of time, soft problems will be frequently reported when the power is transmitted again.
Coping strategy: In addition to equipment maintenance, the inverter should be kept live for a long time. In addition, the upper and lower fans of the inverter control cabinet should be opened, and the drying agent should be placed in the cabinet or the heater should be actively controlled by temperature and humidity to keep the ventilation and environment dry.
Myth 3: The inverter control cabinet installed in the open air or dust environment is sealed type
The inverter control cabinet used in some factories and mines, basements, and open-air installations will withstand the harsh test of harsh environments such as high temperature, dust, and humidity. For this reason, many users will choose a sealed type of inverter cabinet. Although this can play the role of rainproof and dustproof to a certain extent, it also brings the problem of poor heat dissipation of the inverter.
Disadvantages: The tight sealing of the control cabinet will cause the internal components to overheat due to the insufficient ventilation and heat dissipation capacity of the inverter, and the maintenance action of the thermal components will cause the equipment to trip, and the equipment will be forced to stop operation.
Strategy: Install a breathable rain cover on the upper part of the inverter control cabinet with a dust filter and act as an exhaust port. The lower part is also the same slotted device with a strainer fan that acts as an air intake. It can form air circulation and filter dust in the environment together. Cooling air flow direction: from the bottom to the top. The distance between the transverse devices between the inverters should not be less than 5mm, and the temperature of the cooling air entering the inverter should not exceed +40 degrees Celsius. If the ambient temperature is above +40 degrees Celsius for a long time, consider installing the inverter in a small room with air conditioning.
In the control box, the inverter should generally be installed in the upper part of the box, and it is absolutely not allowed to put the heating element or the component that is easy to generate heat close to the bottom of the inverter.
Myth 4: In order to improve the voltage quality, the power factor compensation capacitor is connected in parallel at the output end of the inverter
Due to the limitation of power capacity, the voltage quality of some enterprises is not guaranteed, especially when large-scale electrical equipment is put into use, it will cause the bus voltage in the plant to decrease, and the load power factor will decrease significantly. In order to improve the voltage quality, users usually connect power factor compensation capacitors in parallel at the output of the inverter, hoping to improve the power factor of the motor.
Disadvantage: Connecting the power factor compensation capacitor to the surge absorber on the motor cable (between the inverter and the motor) will not only reduce the control accuracy of the motor, but also form a transient voltage on the output side of the inverter, causing permanent damage to the inverter. If a power factor compensation capacitor is connected in parallel on the three-phase input line of the inverter, it is necessary to ensure that the capacitor and the inverter are not charged together to prevent the surge voltage from damaging the inverter. The current flowing into the inverter is used to improve the power factor, but the charging current cannot be started because the charging current constitutes the overcurrent problem of the inverter.
Strategy: Remove the capacitor and work it, as for improving the power factor, it is effective to connect the AC reactor on the input side of the inverter.
Myth 5: The circuit breaker is used as the thermal overload and short-circuit maintenance of the inverter, which is better than the fuse
The circuit breaker has a relatively complete maintenance function, which has been widely used in power distribution equipment, and has a tendency to replace the traditional fuse. At present, the complete sets of frequency conversion speed control equipment produced by many manufacturers are basically equipped with circuit breakers (air switches), in fact, there are also some safety risks.
Disadvantages: When the power cable is short-circuited, the circuit breaker maintenance action trips due to the inherent action time of the circuit breaker itself and the delay occurs (Official Account: Pump Steward), during which the short-circuit current will be introduced into the inverter, resulting in component damage.
Strategy: As long as the cable is selected according to the rated current, the inverter drive unit can maintain itself, the input terminal and the motor cable to prevent thermal overload, and there is no need for additional rated thermal overload maintenance equipment. Equipped with a fuse, it will be able to maintain the input cable in the event of a short circuit, reduce device damage and prevent damage to connected equipment in the event of a short circuit inside the transmission.
Check that the fuse of the equipment should be less than 0.5 seconds in action. The moment of operation depends on the type of fuse (gG or aR), the impedance of the power supply network, the cross-sectional area of the power cable, the material and the length. When the gG fuse is used for more than 0.5 seconds, the fast melt (aR) reduces the operating time to an acceptable level in most cases. It is necessary for the fuse to be of the non-delay type.
Circuit breakers do not provide maintenance to the transmission equipment quickly enough because they react slower than fuses. Therefore, when quick maintenance is required, fuses should be used instead of circuit breakers.
Myth 6: The inverter selection only needs to consider the load power
When purchasing a frequency converter, many users usually only match the capacity of the drive motor to the power of the drive. In fact, the load driven by the motor is different, and the requirements for the inverter are also different.
Disadvantages: Because of the difference in the load characteristics of the motor, if the inductive factors are not fully considered, it may cause damage due to improper use of the inverter, and because it is not equipped with the necessary braking unit and filter, it may cause safety risks.
Coping strategy: According to the characteristics and types of loads, the capacity and equipment of the inverter should be reasonably selected.
1) Fans and pumps are the most common loads: the requirements for the inverter are the simplest, as long as the inverter capacity is equal to the motor capacity (air compressor, deep water pump, sediment pump, and rapidly changing music fountain need to increase the capacity).
2) Crane load: This type of load is characterized by a large impact when starting, so the inverter is required to have a certain margin. Together, when the elbow is placed under the weight, there will be energy feedback, so it is necessary to use the braking unit or choose the common bus method.
3) Uneven load: some loads are sometimes light and sometimes heavy, at this time, the inverter capacity should be selected according to the condition of heavy load, such as rolling mill machinery, crushing machinery, mixer, etc.
4) Large inertia load: such as centrifuge, punch, cement plant rotary kiln, this kind of load inertia is very large, so it may vibrate when starting, and there is energy feedback when the motor decelerates...... A slightly larger inverter should be used to accelerate the operation and prevent vibration. Cooperate with the braking unit to eliminate the regenerative energy.
|
More on that
|
The main structure of LS power AC contactor
The operating principle of the contactor is: when the contactor coil is energized, the coil current will generate a magnetic field, and the generated magnetic field will make the static iron core attract the moving core with electromagnetic attraction, and drive the communication contactor point action, the normally closed contact is disconnected, and the normally open contact is closed, and the two are linked. When the coil is de-energized ...
|
|
Automatic adjustment of motor parameters - LS power generation
Step 1: If the motor can be completely separated from the load, in the case of a power failure, the motor is mechanically separated from the load, and the motor is allowed to rotate freely without load.
Step 2: After powering on, select the VFD command source (F0-04) as the command channel of the operation panel.
...
|
|
Inverter exception handling method - LS power generation
1. The working temperature of the inverter is high
1. Check whether the ambient temperature of the inverter is too high;
2. Check whether the cooling fan inside the device is working properly;
3. Check whether the ventilation pores and mask grilles are blocked;
4. Check if the load is too heavy.
...
|
|
Parameter setting of LS power inverter
The inverter is a high-tech intelligent product, in order to let it complete the specified control mission, it must be set parameters, otherwise, it is like the computer is not installed and used, and it cannot be operated normally. The parameter setting is carried out by the control surface of the inverter. All kinds of inverters ...
|
|
Introduction to LS Master-K series PLC programming
LS is an electrical equipment company affiliated to LG, kglwin3.62 programming software Chinese version is a professional plc programming software designed to help daily more efficient planning and development software, the software supports the programming and debugging of LG Master-K series and LG MASTER-K series, and provides ...
|
|
Inverter life extension method - LS power generation
1. The inverter should not be installed on the equipment with a sensation, because the main circuit connection screw in the inverter is easy to loosen, and many inverters are damaged due to this reason.
2. Wiring problem: the input terminal of the inverter should be connected to a ...
|
|
What are the components of the PLC?
The basic components of PLC for power production:
1. Memory
The memory that registers the architecture software is called the architecture program memory.
The memory that registers the application software is called the user program memory.
2. Power supply
...
|
|
LS MASTER-K120S series PLC features and advantages
(1) This series is divided into two types: economic type and standard type, which can meet the requirements of different customers:
Economical: 10/14/20/30 points (10/14 points with 2 built-in analog potentiometers), up to 70 points.
Standard type: 20/30/40/60 point DR/DRT (2-axis position ...
|
|
LS Electric's motion control system solution on pillow (horizontal) packaging machine
The pillow packaging machine mainly performs the operation of product forming, positioning, packaging and sealing, etc., and the equipment is composed of the packaging film shaft that provides the packaging film, the feeding shaft that provides the material, the cutter shaft that performs the sealing and cutting operation and the discharging shaft after the product packaging is completed, and the equipment structure diagram is as follows:
...
|
|
Analysis of the problem of LS power inverter
1. What is the maintenance function of the inverter?
Maintenance functions can be divided into the following two categories:
(1) After detecting the abnormal situation, the correction action is automatically carried out, such as overcurrent loss speed avoidance, regeneration overvoltage stall avoidance.
(2) Block the PWM control signal of power semiconductor equipment after detecting the abnormality ...
|
|
Fault analysis of servo motors – LS power generation
1. Problem phenomenon: servo error OL, servo motor can not start, and there is abnormal sound problem analysis and possible causes:
(1) Bearing damage, foreign objects falling and stuck, stator magnet bursting and falling or moving tissue jamming caused by the motor itself.
(2) ...
|
|
How LS produces power PLC operation
Although many relays, timers and counters are often used in the ladder diagram programs used by LS PLC, LS PLC does not have these hardware physically, but uses memory and program programming methods to make logic control modifications, and connects external machines through output components.
|
|
Faulty failure with soft starter - LS generates electricity
In the use of soft starters, some users often have some wrong concepts:
1. It is believed that whether the motor can be started successfully is related to the function of the soft starter, and a good brand or even a foreign brand should be selected under heavy load.
2. When the motor is not ...
|
|
The difference between multi-function and general-purpose inverters
Multi-function inverters need to meet the following two conditions:
First, it can be driven by constant torque load, regardless of the type of machine, and can ensure continuous operation even if the load fluctuates greatly. If the above conditions are not satisfied, the inverter will be easy to stop, difficult to start again, and resistant to ...
|
|
The size of the contactor is selected by the type of contactor - LS produces electricity
1. Select the corresponding category of contactor according to the control object, operation times and application category of the contactor.
2. Select according to the rated voltage of the line at the application location.
3. Select the rated current of the main contact of the contactor according to the load capacity.
4. About the voltage level of the lead coil ...
|
|
The given way of the inverter - LS generates electricity
Frequency given meaning and given method
The speed of the motor can be changed by changing the output frequency of the inverter. In order to adjust the output frequency of the inverter, the inverter must supply the signal of the changed frequency, which is called the frequency given signal.
|
|
DC motor troubleshooting - LS power generation
1. The speed of the motor slows down, and the cause of the problem of sound disorder may occur in the electronic speed stabilization device and the motor itself. If there is no problem with the power supply, most of the motor itself has a problem. It can be repaired by replacing the new motor and dismantling and repairing the motor. Dismantling and repairing the motor ...
|
|
Relationship between motion control and frequency converter
Motion control has a significant period characteristic, it is a combination of a variety of high-tech to push industrial automation, office automation and home automation to a higher stage. At present, the motion control is mainly composed of three parts: inverter, motor and controller.
...
|
|
Dealing with the "transient" fault method of DP slave - LS power generation
Due to poor contact of network connectors, or due to disturbance and other problems, DP networks that have been used for a long time may show a "transient disconnection" situation, that is, occasionally disconnected instantaneously, and quickly recover to normal. If OB86 is not downloaded, the CPU will stop during a transient outage. Now all over the option to download a ...
|
|
Misunderstanding of power-saving and energy-saving use of inverter - LS power generation
Industrial control automation products inverters are described as power-saving, energy-saving control automation products, therefore, many people will think that as long as the equipment is installed with inverters, it will be able to save energy and electricity, but this is not the case.
The inverter of industrial automation products itself produces energy-saving and power-saving ...
|
|
Contact
working hours
