1. Water line for process. Where it is installed on the ground and the water consumption is not large, it should be ensured that there is a venting valve at the end of the pipeline to keep the water flowing to prevent freezing. If conditions permit, heat preservation should be added to the pipeline.

2. The water line used intermittently must be installed with electric heating cable for heat preservation, otherwise it will not be used.

3. For water lines not used in winter, the flanges on both sides should be dismantled, and the water should be drained. If conditions permit, the industrial wind should be used to ensure that the water in the pipeline is not filled. If the switch is not strict, it should be Add blind plates at the flanges that are disassembled at both ends, and register and hang them.

4. For some pipelines that are not used in normal production, due to long-term deactivation, there may be accumulated water in the dead corner and frozen. Once used, it will cause nowhere and affect production. Before such a pipeline enters the winter, the pipeline should be unblocked and replaced with an appropriate flow rate, and the relevant valve is closed to maintain the standby state.

5. Fire hydrant of fire water line system, fire water line valve well, etc., it is necessary to close the valve in the valve well and put the water in the water plug to ensure that the water hydrant can be used at any time. A double-layer manhole cover (one of which is an insulated manhole cover) should be used in the fire well.
Freeze processing

After the equipment is frozen, steam or thermal hydrolysis should be applied. The thawing of cast iron pipelines and equipment should be slow. Explosion-proof, freeze-thawed pipelines or equipment are prohibited from heating under sealed conditions. The venting should be opened first, and the horizontal tubes should be thawed from low to high. From top to bottom, if there is a crack, it should be reported.
Factory antifreeze 30 small knowledge

1. Do a good job in personal protection, wear warm, and do the anti-skid work of the tower under the tower during the inspection process.

2. Strengthen the dehydration work and discharge the moisture of each dehydration point in time to prevent freezing.

3. Pay attention to the fact that the upper level valve of the liquid level gauge on the instrument level gauge will have a frozen plug which will affect the real liquid level. The freezing block at the head of the remote liquid level gauge will affect the mechanical rotation and current conduction. Affect the true level.

4. The temperature of the circulating water is not easy to control too low, and can not be lower than 8 degrees. After being lower than octave, the secondary line of the cooler will be blocked by freezing, and the pipe will be cracked if it is severe.

5. Insulate the pipeline in the circulating water stagnant water zone of the workshop; the decommissioned circulating water pump adopts the reverse flow measure and is discharged.

6. Equipment that is deactivated in the workshop, such as: make-up water pump, circulating water pump, cooler, condenser, etc., should adopt measures such as water discharge and regular inspection. The compressor cooling water is regularly checked by the operator to ensure that the water valve remains open.

7. If the liquid hydrocarbon pipeline is frozen, when the steam purges the pipeline, pay attention to the physical explosion, do not force the purge, and slowly preheat.

8. The on-site pressure gauge will also have an illusion in the case of freezing, and judge according to experience. If it is not certain, it should be reported in time for processing.

9. When purging the frozen plug line, use steam to purge the elbow.

10. Pay attention to the enhanced deliquoring of the natural gas pipeline to prevent the liquid from being brought into the boiler. Check the natural gas line to prevent the crystal structure from being frozen due to freezing.

11. Strengthen the inspection and check the temperature of each point.

12. The raw water pipeline should be prevented from shutting down and maintaining long water flow.

13. Discontinued equipment, the blind line should be added to the connection between the pipeline and the production system, and the accumulated water should be drained and purged. Open-air equipment and open equipment to prevent stagnant water from freezing and freezing equipment. Open-air equipment needs to increase the number of inspections and the number of vehicles.

14. All equipments for production, living and temporary decommissioning, water vapor pipelines, control valves shall have anti-freezing and thermal insulation measures, clean water discharge or adopt a method of maintaining a small amount of long water flow and small over-gas to meet the requirements of both anti-freeze and saving. Be sure to purge after stopping the water and stopping the steam.

15. Strengthen the inspection and dehydration, check the dehydration of the low point of each equipment and the low point of the pipeline, the pump cooling water can not be interrupted, the heating and heating are kept unblocked, the pressure gauge and the liquid level gauge should be checked frequently, the steam and water hose joints, the steamed bread Keep the steam flowing long.

16. Valves that do not move can not be hard-switched, motorized discs do not move, and must not be activated.

17. The frozen iron valve should be heated slowly with warm water or a small amount of steam to prevent sudden heat damage.

18. Construction and domestic water should be managed to discharge to the trench or not affect the passage. The ice skates should be destroyed at any time.

19. Strengthen management to establish anti-freeze anti-condensation accounts (including accident registration, anti-freeze anti-coagulation equipment in good condition, easy to freeze the pipeline, etc.).

20. Valve wells, fire hydrants, and trenches at low temperature should be inspected one by one, draining water, and taking anti-freeze insulation measures.

21. It is strictly forbidden to use high-pressure steam for heating to prevent high-pressure steam from entering the low-pressure system. High and low pressure steam return pipes are not allowed to collude with each other. A pressure reducing valve shall be provided on the steam heating radiator line, the pressure gauge for the pressure reducing valve shall be verified, and the radiator shall be used after the exhaust gas is leak tested.

22. Everything in the workplace must be clear before the accumulation of water, snow and ice.

23. Therefore, the steam line (except the fire steam) closes the root valve, closes the wall valve, opens all the venting valves, drains the water, and purifies it with nitrogen.

24. All condensing points need to be discharged every hour.

25. After the circulating water system stops, you need to empty the low point to open all the water and blow it off with the wind.

26. The adsorption tower, desulfurization tower, water washing tower and gas-liquid separator sewage pipeline outside the workshop shall be anti-freezing by electric heating cable. The water separator and the cooler in the workshop are cleaned in a timely manner after being stopped.

27. When the indoor heating is stopped, the safety facilities such as tap water, eye washers and fire fighting boxes in the workshop shall be equipped with electric equipment to prevent freezing.

28. If water is sprayed on the floor and platform of the workshop, clean it immediately to prevent freezing. Workshop personnel improve safety awareness and awareness when climbing the platform and climbing stairs.

Misunderstanding 1: Connect the electromagnetic switch and electromagnetic contactor in the output circuit of the inverter

In practical applications, some occasions need to use the contactor to switch the inverter: if the frequency conversion fault is switched to the power frequency state, or when one to two is used, one motor fails, the inverter turns to drag another Motor and other conditions. Therefore, many users will think that installing electromagnetic switches and electromagnetic contactors in the output circuit of the inverter is a standard configuration, which is a way to safely disconnect the power supply. In fact, this practice has a great hidden danger.

Disadvantages: When the inverter is still running, the contactor is disconnected first, and the load is suddenly interrupted. The surge current will cause the overcurrent protection action, which will have a certain impact on the rectifier inverter main circuit. Serious, it may even cause damage to the inverter output module IGBT. At the same time, when the load is inductive motor, the inductive magnetic field energy cannot be released quickly, which will generate high voltage and damage the insulation of the motor and the connecting cable.

Coping strategy: Connect the output side of the inverter directly to the motor cable. The normal start-stop motor can be realized by triggering the inverter control terminal to achieve the soft start and soft stop effect. If it is necessary to use the contactor on the output side of the inverter, it is necessary to control the interlock between the output of the inverter and the action of the contactor to ensure that the contactor can only act when there is no output from the inverter. .
Mistaken 2 When the equipment is out of service normally, disconnect the AC input power of the inverter.

When the equipment is out of service normally, many users are accustomed to disconnecting the AC input power switch of the inverter, which is considered to be safer and energy-saving.

Disadvantages: This approach seems to protect the inverter from power failures. In fact, the inverter does not charge for a long time, and the humidity of the on-site environment will cause the internal circuit board to be damp and slowly oxidize and gradually appear a short circuit. This is the reason why the soft fault is frequently reported when the inverter is powered off again after a period of power failure.

Coping strategy: In addition to equipment maintenance, the inverter should be in a live state for a long time. In addition, the upper and lower fans of the inverter control cabinet should be turned on, the desiccant should be placed in the cabinet or the automatic temperature and humidity control heater should be installed to keep the ventilation and the environment dry.
Misunderstanding three inverter control cabinet installed in open air or dust environment adopts sealed type

In some factories, mines, basements, open-air installation and use of inverter control cabinets, will withstand the harsh test of harsh environments such as high temperature, dust, humidity. To this end, many users will choose a sealed type of frequency conversion 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 inverter to overheat due to insufficient ventilation and heat dissipation capability, and the thermal element protection action will cause the fault to trip and the equipment will be forced to stop.

Coping strategy: Install a breathable rain cover on the top of the inverter control cabinet with a dust filter and as an exhaust port. The lower part is also slotted to install a fan with a strainer as an air inlet. Air circulation can be formed while filtering dust in the environment. Cooling air flow direction: from bottom to top. The lateral installation distance between the inverters should be no less than 5mm, and the cooling air temperature 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 frequency converter in an air-conditioned chamber.

In the control box, the inverter should generally be installed in the upper part of the cabinet. It is absolutely not allowed to install the heating element or the heat-prone component close to the bottom of the inverter.
Misunderstanding 4 is to improve the voltage quality, parallel power factor compensation capacitors at the output of the inverter

Due to the limitation of power consumption, some enterprises cannot guarantee the voltage quality. Especially when large-scale power equipment is put into use, the bus voltage in the station will decrease and the load power factor will obviously decrease. In order to improve the voltage quality, the user usually parallels the power factor compensation capacitor at the output of the inverter, hoping to improve the motor power factor.

Disadvantages: Connecting a power factor compensation capacitor and a surge absorber to the motor cable (between the drive unit and the motor), their effects not only reduce the control accuracy of the motor, but also form a transient voltage on the output side of the drive unit. Causes permanent damage to the ACS800 drive unit. If a power factor compensation capacitor is connected in parallel on the three-phase input line of the ACS800, it must be ensured that the capacitor and the ACS800 are not charged at the same time to prevent the surge voltage from damaging the inverter. The current in the inverter flows into the capacitor for improving the power factor, and the inverter overcurrent (OCT) is caused by the charging current, so it cannot be started.

Coping strategy: After the capacitor is removed and operated, as for improving the power factor, it is effective to connect the AC reactor to the input side of the inverter.
Mistake 5: Use circuit breaker as thermal overload and short circuit protection of inverter, the effect is better than fuse

The circuit breaker has a relatively complete protection function and has been widely used in power distribution equipment, which has a tendency to replace the traditional fuse. Nowadays, many sets of variable frequency speed control equipment produced by many manufacturers are basically equipped with circuit breakers (air switches). In fact, there are some hidden dangers.

Disadvantages: When a short-circuit fault occurs in the power cable, the circuit breaker protection action trips due to the inherent operating time of the circuit breaker itself. During this period, the short-circuit current is introduced into the inverter, causing component damage.

Coping strategy: As long as the cable is selected according to the rated current, the drive unit protects itself, the input and the motor cable to prevent thermal overload and does not require additional thermal overload protection. Configuring the fuse will protect the input cable in the event of a short circuit and reduce damage to the unit and prevent damage to the connected equipment when the drive is internally shorted.

Check that the configured fuse action time should be less than 0.5 seconds. The action time depends on the type of fuse (gG or aR), the impedance of the supply network, the cross-sectional area of ​​the power cable, the material and the length. When using a gG fuse for more than 0.5 seconds of action time, fast-blow (aR) can reduce the action time to an acceptable level in most cases. The fuse must be of no delay type.

Circuit breakers do not provide fast enough protection for the transmission equipment because they react more slowly than fuses. Therefore, fuses should be used instead of circuit breakers when fast protection is required.
Mistaken six inverter selection only need to consider load power

When many users purchase inverters, they usually only match the inverter capacity based on the power of the drive motor. In fact, the load driven by the motor is different, and the requirements for the inverter are different.

Disadvantages: Due to the difference in load characteristics of the motor, if the comprehensive factors are not fully considered, the inverter may be damaged due to improper use, and the safety risk may be caused by not having the necessary braking unit and filter.

Coping strategy: For the characteristics and types of the load, the capacity and configuration of the inverter should be reasonably selected.

1. Fans and pumps are the most common loads: the requirements for inverters are the simplest, as long as the capacity of the inverter is equal to the capacity of the motor (air compressors, deep pumps, sediment pumps, fast changing musical fountains need to increase capacity) .

2, crane type load: This type of load is characterized by a large impact at startup, so the inverter is required to have a certain margin. At the same time, if the elbow is placed under the weight, there will be energy feedback, so use the brake unit or use 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 heavy load, such as rolling mill machinery, crushing machinery, mixer, etc.

4, large inertia load: such as centrifuge, punch, cement plant rotary kiln, such load inertia is very large, so it may oscillate when starting, there is energy feedback when the motor decelerates … should be used to speed up the inverter with a slightly larger capacity Start to avoid oscillation. The brake unit is used to eliminate the feedback energy.

There are still some unsatisfactory inverters in operation, which leads to shortened service life and correspondingly increased maintenance of the devices, which increases maintenance costs.

Now we analyze the application environment, power quality and electromagnetic interference of the inverter, and put forward some problems and suggestions for improvement. I believe this will help everyone.

working environment

In the actual application of the inverter, most people install the inverter directly on the industrial site in order to reduce the cost. The work site generally has the problems of large dust, high temperature and high humidity. In some industries, there are metal dust and corrosive gas problems. Corresponding countermeasures must be made according to the situation on site.

1) The frequency converter should be installed inside the control cabinet.

2) The inverter should be installed in the middle of the control cabinet; the inverter should be installed vertically, and the upper and lower sides should be protected from large components that may block the exhaust and air.

3) The minimum distance between the upper and lower edges of the inverter from the top, bottom, or partition of the control cabinet, or large components that must be installed, should be greater than 300mm.

4) If the special user needs to remove the keyboard during use, the keyboard hole of the inverter panel must be tightly sealed with tape or replaced with a dummy panel to prevent dust from entering the inverter.

5) Most of the printed boards and metal structural parts inside the inverter are not specially treated for moisture and mildew. If the equipment is in a harsh working environment for a long time, the metal structural parts are prone to rust. When the conductive copper strip is operated under high temperature, it will be more rusted. Corrosion will be caused to the small copper conductor on the microcomputer control board and the drive power board. Therefore, for applications where it is used in wet and corrosive gases, basic requirements must be placed on the internal design of the frequency converter used.

6) When using the inverter in a dusty place, especially in a place with multi-metal dust and floc, the overall requirements of the control cabinet are sealed. The air inlet and outlet are specially designed for ventilation; the top of the control cabinet should have a protective net and a protective roof. Cover the air outlet; the bottom of the control cabinet should have a bottom plate and air inlet, inlet holes, and install a dust filter.

Electromagnetic interference

In modern industrial control systems, microcomputer or PLC control technology is often used. In the process of system design or modification, the interference of the inverter to the microcomputer control board must be paid attention to. Since some microcomputer control boards designed by inverters do not comply with EMC international standards, conduction and radiation interference will occur after using the inverter, which often leads to abnormal operation of the control system. The following methods are available for your reference.

1) Adding an EMI filter to the input end of the inverter can effectively suppress the conducted interference of the inverter to the power grid. Adding input AC and DC reactors can improve the power factor and reduce harmonic pollution, and the overall effect is good. When the distance between some motors and the inverter exceeds 100m, it is necessary to add an AC output reactor on the inverter side to solve the leakage current protection caused by the distribution parameters of the output wires to the ground and reduce the external radiation interference.

One method is to thread the steel pipe or shield the cable to reliably connect the steel casing or cable shield to the earth. In the case where an AC output reactor is not added, the use of steel pipe threading or shielded cable increases the distributed capacitance of the output to the ground and is prone to overcurrent.

2) Electrically shield and isolate the analog sensor sense input and analog control signals. In the design process of the control system composed of the inverter, it is recommended not to use the analog control as much as possible, especially if the control distance is greater than 1m and is installed across the control cabinet. Because the inverter generally has multi-speed setting and switching frequency input and output, it can meet the requirements. If it is necessary to use analog control, it is recommended to use a shielded cable and ground the remote point on the sensor side or the inverter side. If the interference is still severe, DC/DC isolation measures are required. A standard DC/DC module can be used, or a method of optically isolating the v/f conversion and then using the frequency setting input.

3) Adding EMI filter, common mode inductor, high frequency magnetic ring, etc. to the input power of the microcomputer control board can effectively suppress the conducted interference. In addition, in the case of severe radiation interference, such as the presence of GSM or PHS base stations, a metal mesh shield can be added to the microcomputer control board for shielding.

4) Good grounding. The grounding wire of the strong electric control system such as the motor must be reliably grounded through the grounding busbar, and the shielding ground of the microcomputer control board should be grounded separately. For some severe interference situations, it is recommended to connect the sensor and I/0 interface shielding layer to the control ground of the control board.

Grid quality

In the case of impact loads such as electric welders, electric arc furnaces, rolling mills, etc., the voltage often flickers; in a workshop, when there are multiple inverters and other capacitive rectification loads, the harmonics generated are very good for the quality of the grid. Severe pollution has a considerable destructive effect on the equipment itself, but it can not be continuously operated normally, and the equipment input circuit is damaged. The following methods can be used to solve.

1) In the impact load such as electric welding machine, electric arc furnace, rolling mill, etc., it is recommended that the user increase the reactive static compensation device to improve the power factor and quality of the power grid.

2) In the workshop where the inverter is concentrated, it is recommended to use centralized rectification and DC common bus power supply. Users are advised to use a 12-pulse rectification mode. The utility model has the advantages of small harmonics and energy saving, and is particularly suitable for frequent starting and braking, and the electric motor is in the occasion of electric operation and power generation operation.

3) Install passive LC filter on the input side of the inverter to reduce input harmonics, improve power factor, high reliability and good effect.

4) The input PFC device is installed on the input side of the inverter, which has the best effect but high cost.

Starting from the problems in the actual application system of the inverter, from the interference of external factors, the use environment, the quality of the power grid, etc., the influence of the bad factors on the inverter is put forward in the actual application, and then the problem is summarized. Some methods to solve the problem and suggestions for improvement can have a good effect on the extended service life of the frequency converter, and have certain reference value in practical engineering applications.

1. The place where the load torque is large and the low speed is running;

2. Closed loop control is required;
Generally, there are many applications in these two types of occasions.
Specific applications are as follows
Under the premise of not having any negative impact on the normal use of the escalator, the concept of vector frequency conversion speed regulation is introduced. That is, the inverter runs according to the signal generated by the sensor. When someone is riding, the escalator runs at the original speed (50 Hz); when there is no one, the escalator decelerates to a low speed or stops running.
The system requires the inverter to start smoothly, with good acceleration performance, large starting torque and strong overload capability. At the same time, when the inverter speed control system fails, the control system automatically switches to the power frequency operation to ensure the normal implementation of the escalator transport function. .
For the passenger escalator, the peak period is generally used in the afternoon and evening hours, and the usage rate in the remaining periods is low, which has considerable energy saving space. According to the above transformation principle, from the perspective of investment cost and automation level, the following variable frequency drag scheme is proposed:
·The SAJ-8000G inverter is used to drive the elevator main engine. The inverter adopts multi-speed control mode and sets two operating frequencies: main frequency (low speed) and multi-speed frequency 1 (high speed).
· Install an infrared sensor switch at the beginning and the end of the elevator. When the passenger passes the elevator, the infrared sensor switch is triggered and sends a switch signal to the inverter;
· When there is passenger flow, the infrared sensor switch is triggered, the inverter immediately accelerates to the multi-speed frequency 2, and the elevator runs at high speed;
·When the elevator runs at high speed, the built-in timer of the inverter starts to count. If there is no passenger passing the elevator during the time period, the inverter will automatically switch to the multi-speed frequency 1 after the timer is finished, and run at low speed;
· If a passenger re-triggers the photoelectric switch during the timer period, the timer will be re-timed;
· For the elevator up and down, the peripheral control adopts switch interlock to ensure the normal operation of the escalator system;
• To consume the downstream or the excess energy generated during the braking process, a braking resistor must be added to the inverter.
The vector universal inverter is used to drive the elevator main engine, which not only can meet the requirements of stable starting and running of the system, large starting torque, strong overload capability and high speed adjustment accuracy; and the motor can reduce mechanical wear and prolong service life by frequency conversion. The work is safer and more reliable, because the adjustment motor has a large speed space, which makes the system more energy-saving.

+Advantages of  Frequency inverters

Photovoltaic water pump system is also called photovoltaic lift water system, which consists of photovoltaic solar panels, special inverters for photovoltaic, water pumps, and water storage devices. The principle is to use semiconductors to absorb solar radiation energy, and convert it into direct current, and then convert it into alternating current through a photovoltaic inverter to drive the pump to lift water.

Photovoltaic pump system features:
Clean Energy: Solar energy is driven as a power source and has zero pollution to the environment;
Affordable: No need to lay power lines, greatly reducing system construction costs;
Safe and reliable: automatic operation, no need to be on duty, to replace water storage power storage, direct drive pump water, to avoid large-scale laying of the hidden safety problems caused by the cable, high reliability, significantly reduce the system’s construction and maintenance costs.
Intelligent adjustment: adjust the speed of the pump according to the change of the sunshine intensity so that the output power is close to the maximum power of the solar array; when the sunshine is sufficient, the rotation speed of the water pump does not exceed the rated rotation speed; when the sunshine is insufficient, according to the set conditions, automatic Stop or switch to commercial power to ensure the system continues to operate economically.
Widely used: The water pump is driven by a three-phase AC motor, pumping water from a deep well, injecting a water storage tank/pool, or directly accessing an irrigation system. According to actual system requirements and installation conditions, different types of pumps can be used for work. And can provide economical and effective solutions based on the needs of different regions and customers.

Photovoltaic water pump to inverter requirements
1. With MPPT algorithm, adjust the pump speed according to the change of sunshine intensity so that the output power is close to the maximum power of the solar array. Due to the non-linearity of the output characteristics of the photovoltaic array, its output is affected by the light intensity, ambient temperature and load conditions. Under a certain light intensity and ambient temperature, the photovoltaic array can work at different output voltages, but only at a certain output voltage value. At this time, the output power of the photovoltaic cell can reach its maximum value. Therefore, in the solar photovoltaic pump system, to improve the system efficiency, the output power of the photovoltaic array must be detected in real time and the operating point of the photovoltaic cell must be adjusted so that it always operates near the maximum power point, so as to satisfy the solar energy requirement under different solar illumination conditions. More is converted into electrical energy to enable the pump to work efficiently and stably. Therefore, Maximum Power Point Tracking (MPPT) is the core function of the PV Pump Frequency Converter.
2, with a dry burning detection, automatic protection of the pump. The working environment of the water pump is in the water. The water pump motor is used to radiate heat by water. It is forbidden to run under broken water. However, the water level of the water pump is very different according to the amount of water supply and the change of the water source. Burning the pump motor affects the reliability of the system.
3, according to changes in light intensity, automatic sleep wake up. In order to meet the requirements of the system’s automatic work, the system should have the function of self-diagnosis and automatic start-up. The control system should conduct self-testing and pre-judgment before the pump work, and start the photovoltaic pump work or charge the lighting battery after the conditions are met; In cloudy and thundery weather, the system can stop the work of the photovoltaic pump according to the detected data. When the light meets the working requirements of the photovoltaic pump, the system can automatically resume operation.
4, the system has lightning protection and other functions, when the over-voltage, under voltage, over-current, overload, overheating, water tank full of water, water pump and other failures have been lifted, the system can automatically resume working after self-diagnosis.
5. It can cooperate with water level switch and water tower to store water and improve water use efficiency.

I. Preparation before power on
1, first check the inverter wiring and wiring. a. Check whether the main power connection of the inlet and outlet wires is correct and reliable. Whether the power supply voltage level meets the requirements of the inverter instruction and the connection is firm. Insulation damage. Check carefully whether the terminal block is loose or not, whether there is a hidden fault such as a short circuit. Grounding is good. b. Check whether the incoming connection and voltage level of the control circuit in the inverter cabinet meet the requirements of the inverter cabinet. Whether the connection cables are firm, whether the insulation layer is damaged or not, and whether the connection plugs of the circuit boards are firm. c. Clean up the sundries in the inverter cabinet and reconfirm the connection of the main power inlet, control circuit, grounding, and neutral wires. Keep the environment surrounding the inverter clean and dry. Do not place any noise near the inverter. Things. Check carefully for missing screws and wires to prevent short circuit accidents caused by small metal objects.

2. Consult the user’s system control requirements and pipe network pressure setting requirements and record them.

3. If the frequency conversion cabinet controls the submersible pump, consult the user to specify the motor-related parameters of the submersible pump: rated power, rated speed, rated current, etc., and record it after confirmation. If the centrifugal pump or fan is controlled, the parameters on the motor nameplate are recorded so that the parameters of the motor can be accurately input when the program setting of the inverter is performed, so that the accuracy of the protection of the inverter and the accuracy of the control can be achieved.

4. Check whether the user’s pipe network installation connection is in accordance with our installation plan. If the user does not install and construct according to our drawings, special attention should be paid to the installation position of the single-flow valve and the inspection instrument. We must state to users that they understand the improper installation of the stakes. First, if a deep-well submersible pump is controlled, a single-flow valve is not installed. When the pump is stopped, the water in the pipeline will flow back into the well. This not only results in wasted electricity. Because the submersible electric pump is forbidden to reversely run, the water will cause reverse operation of the submersible electric pump during the returning process, and the loosening of the fasteners in the submersible electric pump will occur for a period of time, resulting in a mechanical failure. Second, because our water supply pipe is a fully enclosed system, the water in the pipe will form an approximately vacuum inside the pipe during the backflow into the well. The pressure detection instrument installed on the pipe will be because of the inside of the pipe. The vacuum negative pressure causes damage, which in turn causes our equipment to fail to start due to the failure of the instrumentation.

5, check the pressure detection instrument and the inverter wiring is firm, the connection is correct. The wiring rules for our pressure detection instrument are: the red wire of the shielded wire is connected to the red lead wire in the instrument, the yellow wire of the shielded wire is connected to the yellow lead wire in the instrument, and the green wire of the shielded wire is connected to the blue lead wire in the instrument. Terminal wiring rules in the inverter: The red wire of the shielded wire is connected to the negative terminal of the feedback terminal in the inverter, the yellow wire of the shielded wire is connected to the input terminal of the feedback terminal in the inverter, and the green wire of the shielded wire is connected to the feedback terminal of the inverter. Power end.

6. Check whether the motor line insulation of the water pump motor is good, whether it is damaged, and whether the wire diameter meets the requirements. First check whether the three-phase resistance of the pump motor is balanced.

1According to the basic principles of electromagnetism, the formation of electromagnetic interference must have three elements: electromagnetic interference sources, electromagnetic interference pathways, and systems sensitive to electromagnetic interference. To prevent interference, hardware anti-jamming and software anti-jamming can be used. Among them, hardware anti-jamming is the most basic and most important anti-jamming measure. Generally, it starts from both resistance and attenuation to suppress interference.

Its overall principle is to suppress and eliminate the interference source, cut off the coupling channel to the system, and reduce the system interference signal. The sensitivity. Specific measures can be used in engineering isolation, filtering, shielding, grounding and other methods.

1. Proper grounding
Through the site’s specific investigation, we can see that the site’s grounding situation is not ideal. Correct grounding can be the most effective way to solve the inverter interference by effectively suppressing external interference and reducing the interference of the device itself to the outside world. Specifically, it is to do the following:
(1) The main circuit terminal PE (E, G) of the inverter must be grounded. The grounding can be shared with the motor carried by the inverter, but it cannot share ground with other devices. It must be grounded separately and connected. The location should be as far away as possible from the grounding point of weak equipment. At the same time, the cross-sectional area of ​​the grounding conductor of the inverter shall not be less than 4mm2, and the length shall be controlled within 20m.
(2) In the ground wire of other electromechanical equipment, the protective earthing and working earthing should be separately set up for the grounding pole, and finally imported into the electrical grounding point of the power distribution cabinet. The shield ground of the control signal and the shield ground of the main circuit conductor shall also be separately provided with the ground electrode, and finally be imported into the electrical grounding point of the distribution cabinet.

2. Mask interference sources
Masking interference sources is a very effective way to suppress interference. Normally, the inverter itself is shielded by a steel shell, which can prevent its electromagnetic interference from leaking. However, the output cable of the inverter is preferably shielded by steel pipe, especially when the inverter is controlled by an external signal (outputs 4~20mA signal from the controller). It is required that the control signal line be as short as possible (generally within 20m), and shielded twisted pairs must be used, and completely separated from the main circuit line (AC380) and the control line (AC220V). In addition, shielded twisted pairs, especially pressure signals, are also required for the electronic sensitive equipment circuits in the system. And all signal lines in the system must not be placed in the same pipe or slot in the main circuit and control lines. For the shielding to be effective, the shield must be reliably grounded.

3. Reasonable wiring
specific method:
(1) The power and signal cables of the equipment should be as far away as possible from the input and output cables of the inverter.
(2) The power lines and signal lines of other equipment should be avoided parallel to the input and output lines of the inverter.
If you still cannot work after taking the above measures, continue the following:

4, interference isolation
The so-called interference isolation means that the interference source is isolated from the vulnerable parts of the circuit so that they do not have electrical connections. An isolation transformer is usually used between the power supply and the amplifier circuit such as the controller and the transmitter to avoid conduction interference. The power isolation transformer can use a noise isolation transformer.

5, set the filter in the system line
The function of the equipment filter is to suppress the interference signal from the inverter through the power line to conduct interference to the power supply and the motor. In order to reduce electromagnetic noise and losses, an output filter can be set on the output side of the inverter; to reduce interference with the power supply, an input filter can be set on the input side of the inverter. If there are sensitive electronic devices in the circuit such as controllers and transmitters, a power noise filter can be set on the power line of the device to avoid conducting interference.

6, using reactors
The proportion of the harmonic components with lower frequency in the input current of the inverter (5th harmonic, 7th harmonic, 11th harmonic, 13th harmonic, etc.) is very high, and they may interfere with other In addition to the normal operation of the equipment, because they consume a large amount of reactive power, the power factor of the line is greatly reduced. Series reactors in the input circuit are effective ways to suppress lower harmonic currents.

Therefore, the anti-jamming measures of the inverter mainly include the installation of AC reactors and filters in the incoming line of the inverter, shielded cables for incoming and outgoing cables, shields of all cables, reactors, filters, inverters and motors. The protective ground is commonly grounded, and the grounding point is separated from other grounding points to maintain a sufficient distance. At the same time, the power cables of signal cables and frequency converters should not be arranged in parallel.
In addition, in order to prevent the frequency converter from interfering with the signal and the control loop, it is necessary to use a separate isolated power supply for the controller, the instrument, and the industrial control computer.

1, The inverter on the computer control panel interference
In the use of inverter control system, the use of more computer or PLC control, the system design or transformation process, we must pay attention to the inverter on the computer control panel interference problems. As the user-designed microcomputer control panel generally poor level of technology, does not meet the EMC international standards, the use of frequency converter, the resulting conduction and radiation interference, often lead to unusual control system work, and therefore need to take the necessary measures.

2, The inverter itself anti-interference problems
When the inverter power supply system near the existence of high-frequency impact loads such as welding machine, electroplating power supply, electrolytic power supply or the use of slip ring power supply, the inverter itself prone to interference due to protection. Recommended users to adopt the following measures:
(1) Add inductor and capacitor on the input side of the inverter to form LC filter network.
(2) The inverter power cable is supplied directly from the transformer side.
(3) A separate transformer may be used where permitted.
(4) In the use of external switch control terminal control, the connection line is longer, it is recommended to use shielded cable. When the control circuit and the main circuit power are buried in the trench, in addition to the control line must be shielded cable, the main circuit line must be used steel pipe threading, reducing mutual interference, to prevent the inverter malfunction.

3, power quality problems
In high-frequency impact load such as welding machine, electroplating power supply, electrolytic power supply and other occasions, the voltage often flicker; in a workshop, there are hundreds of frequency converter and other capacitive rectification load at work, the power grid harmonic is very large, The quality of the grid is very serious pollution, the device itself has a considerable role in the destruction, ranging from not be able to continue normal operation, while causing the equipment input circuit damage. Can take the following measures:
(1) In the high-frequency impact load such as welding machine, electroplating power supply, electrolysis power supply and other occasions, users are advised to increase the static and static compensation device to improve the grid power factor and quality.
(2) In the workshop where frequency converter is more concentrated, it is recommended to adopt centralized rectification and direct current common bus power supply. Users are advised to use 12-pulse rectifier mode. The advantage is that the harmonic is small, energy saving, especially for frequent braking, electric operation and power generation running at the same time.
(3) Addition of passive LC filter on the input side of inverter to reduce input harmonics, improve power factor, lower cost, high reliability and good effect.
(4) Install the active PFC device on the input side of the inverter, the effect is best, but the cost is higher