The VFD frequency inverter for water pump

The load of the production equipment of industrial enterprises is mostly AC asynchronous motors, and the power consumption accounts for about 65% of the total power consumption of the enterprise. Especially the efficiency of the pump load is relatively low. After China joined the WTO in 2002, the enterprise must reduce costs To improve economic efficiency. In order to enhance competitiveness, in reducing production costs, saving electricity is an important economic link. For example, in a water supply station, the water supply system is adjusted according to the demand of water consumption, and the flow rate is adjusted by adjusting the valve of the pump out door. Special personnel are required to watch the valve under different circumstances. The labor intensity is large. At the same time, due to the forced throttling of the valve, the pump forms a vortex impact, which generates strong vibration and noise, which increases the unfavorable loss of the service life and maintenance of the pump. Furthermore, because the torque of the motor is basically constant, the water supply pressure formed by this adjustment method is high, causing severe throttling power loss, reducing the efficiency of the pump, and wasting electric power.

With the development of electric power technology, the frequency conversion speed regulation technology is becoming more and more perfect. The intelligent water supply control system with frequency conversion speed regulation as the core has replaced the previous high-level water tank and pressure tank and other water supply equipment. Therefore, the impact on the power grid during starting is avoided; because the average speed of the pump is reduced, the service life of pumps and valves can be extended; the water hammer effect during starting and stopping can be eliminated. Its stable and safe operation performance, simple and convenient operation mode, and complete and thoughtful functions will make the water supply realize water saving, electricity saving, manpower saving, and finally achieve the purpose of high efficiency operation.

 

Frequency conversion speed regulation has the following advantages:
①The slip rate is small, the slip loss is small, and the efficiency can be as high as 90 ~ 95%.
②Smooth stepless speed regulation is realized, with high precision, wide speed regulation range (0 ~ 100%), and large frequency variation range (0 ~ 50Hz).
③ The starting torque is large (up to 1.1 times of the rated value), and the soft start can reduce the impact of the starting current.
④ Improve the power factor on the grid side.
⑤Inverter can use high-speed 16-bit CPU and special large-scale integrated circuit, use software to realize V / 5 automatic adjustment, with the function of online control with computer programmable controller, easy to realize automatic control of production process.
⑥Easy installation, convenient debugging and simple operation.
⑦Not only suitable for energy-saving speed regulation of pumps and fans, but also suitable for the transformation of old equipment, especially for improving process conditions and product quality.

VSD 220v to 380v Spindle Inverters VFD AC drive frequency converter

Due to national policies and regional restrictions, many regions will now withdraw three-phase 380V industrial power. The cumbersome procedures for applying for three-phase electricity in areas without three-phase electricity, various labor costs, and various hidden costs have caused some Regions cannot use industrial 380V electricity, and general industrial equipment, such as motors, are mostly three-phase 380V, which cannot be operated without three-phase electricity, and can only find ways to convert single-phase 220V to three-phase 380V, but Many single-phase 220V electric liters and three-phase 380V equipment on the market are ridiculously expensive, and many users in need are discouraged. The original machine can only be placed temporarily or used in other places with industrial electricity.

Now our company has introduced a single-phase 220V input to three-phase 380V output boost converter, which can drive the three-phase asynchronous motor to start softly and perform stepless speed regulation. The input power only needs single-phase 220V and output three-phase 380V, and most users can accept the price. It is about 1/10 of the price of the booster on the market. It is small in size and powerful in function. Solve the embarrassing situation that industrial equipment does not have three-phase electricity.

2. Introduction of the principle and characteristics of 220V to 380V inverter

The principle of the frequency converter is the principle of applying frequency conversion technology and microelectronic technology. The power control equipment of the AC motor is controlled by changing the frequency of the working power of the motor, and the power frequency AC with a fixed voltage and frequency is converted into a variable voltage or frequency. The device for alternating current is called “frequency converter”.

The output waveform of the frequency converter is an analog sine wave, which is mainly used for the speed regulation of three-phase asynchronous motor, also known as frequency converter. The frequency converter is mainly composed of rectification (AC to DC), filtering, inverter (DC to AC), braking unit, drive unit, detection unit micro-processing unit, etc. The frequency converter mainly adopts the AC-DC-AC method (VVVF frequency conversion or vector control frequency conversion). First, the power frequency AC power is converted into a DC power through a rectifier, and then the DC power is converted into an AC power that can be controlled by frequency and voltage to supply electric motor.

The 220V to 380V frequency converter converts the power frequency AC 220V power supply to a DC power supply through a rectifier (voltage doubler rectification), and then converts the DC power supply into a three-phase 380V AC power supply that can be controlled by frequency and voltage to supply the motor.

2.1 Inverter function

1. Can reduce the impact on the power grid, it will not cause the problem of excessive peak-valley difference.

2. The acceleration function can be controlled, so as to smoothly accelerate according to the needs of users;

3. The stopping mode of the motor and equipment can be controlled, making the entire equipment and system safer, and the life will be increased accordingly;

4. Control the starting current of the motor, fully reduce the starting current, and reduce the maintenance cost of the motor;

5. Can reduce the wear of mechanical transmission components, thereby reducing procurement costs, while improving system stability.

6. Reduced motor starting current and provide more reliable variable voltage and frequency.

7. Effectively reduce the reactive power loss and increase the active power of the power grid

8. Optimize the technological process, and can change rapidly according to the technological process, but also realize the speed change through remote control PLC or other controllers.

Solar inverter MPPT Photovoltaic Inverter Power Controller

Product introduction


Product name: photovoltaic inverter

Voltage level: 220V / 380V

Product description

The built-in MPPT controller for photovoltaic inverters has an excellent MPPT algorithm suitable for various solar panels. The main circuit uses intelligent power modules with high reliability and a conversion efficiency of about 95%. It is especially suitable for photovoltaic-driven fans and pumps load.

Three, servo drive characteristics of  machine
1.Support boost module , increase PV output voltage;

2. The speed range of the pump can be freely set according to the actual system situation;

3, soft start, reduce the top voltage spikes, with over-voltage, under-voltage, over-current, overload and other protection functions;

4. Support photovoltaic input and AC grid input;

Fourth, matters needing attention
1. Do not use the inverter for overload. For example, the inverter power is lower than the motor power, or the ordinary motor is running more than 50HZ, otherwise the inverter will skip the load protection fault frequently, and even the explosion machine, the motor may be burned due to overheating.

2. The default upper limit frequency of the inverter is 50HZ, and the anyway function is turned off by default. If you need to change it, please contact the manufacturer for after-sale or follow the instructions to operate correctly;

3. Do not connect any switches in series between the output terminals U, V, W of the inverter and the motor, including contactors. Do not use the inverter as a power source. During the operation of the inverter, you cannot suddenly turn on any equipment through the switch.

4. The lead-in distance of the inverter’s operation panel should not be too long. If it exceeds 5M, it is recommended to use an external potentiometer to adjust the speed and connect it with a shielded wire. The terminal control mode can be used for start-stop control;
5. The panel connection cable is too long and is easily affected by harmonic interference, which makes the frequency control of the inverter inaccurate and the frequency fluctuates greatly;

6. The DC input voltage should meet the recommended voltage as much as possible, otherwise the solar energy conversion rate will be reduced;

7. The AC input and DC input switches cannot be closed at the same time, otherwise the inverter or solar panel will be damaged.

Precautions for the surrounding environment of the inverter

The peripheral components of the inverter mainly include cables, contactors, air-openers, reactors, filters, and braking resistors. Whether the selection of the peripheral components of the inverter is correct or appropriate also directly affects the normal use of the inverter and the service life of the inverter. Therefore, after selecting the inverter, we must also correctly select its peripheral components. Below we will briefly explain the precautions for the selection of peripheral equipment.
1
Line breaker setting and selection
In order to protect the primary wiring on the power supply side of the inverter, install a wiring breaker. The choice of circuit breaker depends on the power factor on the power supply side (varies with supply voltage, output frequency, load). The operating characteristics are affected by the high-frequency current, and it is necessary to select a large capacity.
2
Line contactor
The inverter can be used without a line contactor. The line contactor can be stopped, but the brake function of the inverter will not be used.
3
Motor side contactor
If a contactor is provided between the inverter and the motor, it is in principle not allowed to switch during operation. When the inverter is connected during operation, there will be a large inrush current, so the inverter overcurrent protection action. When setting the contactor for switching to the grid, be sure to switch after the inverter stops output and use the speed search function as appropriate.
4
Thermal relay setting
In order to prevent the motor from overheating, the inverter has electronic thermal protection. However, when one inverter drives multiple motors and multi-stage motors, set a thermal relay between the inverter and the motor. The thermal relay is set to 1 times the motor nameplate at 50 Hz and 1.1 times at 60 Hz.
5
Power factor improvement
To improve the power factor, you can insert an AC reactor into the inverter’s incoming line or add a DC reactor to the DC loop. When the inverter output side is connected to the capacitor filter for improving the power factor, there is a danger of damage and overheating due to the high-frequency current output from the inverter. In addition, the inverter will overcurrent and cause current protection. Please do not connect the capacitor filter.
6
About radio interference
There is a high-frequency component in the output (main circuit) of the inverter, which can cause interference to communication devices (such as AM radios) used near the inverter. Filters can be installed to reduce interference. In addition, it is also effective to ground the inverter and the motor and the power supply wiring on the metal pipe.
7
Power cable wire diameter and wiring distance
When the wiring distance between the inverter and the motor is long (especially at low frequency output), the motor torque will drop due to the cable voltage drop; use a sufficiently thick cable wiring; when the operator is installed elsewhere, use a dedicated connection. Cable; when operating remotely, the distance between analog, control line and inverter should be controlled within 50 meters; the control signal should be properly shielded from ground.

Four common faults and incentives of the inverter

As a very popular control device in the field of electronic control, the frequency converter almost penetrates into every corner of industrial production activities. However, for some newcomers or newcomers who are just beginning to contact the inverter, they are still relatively unfamiliar and mysterious, especially if the inverter fails, it is easy to get started. Today, based on years of experience in using and overhauling inverters, I have summarized the four major faults common to inverters and given the relevant incentives for causing them.

First, over current (short circuit)
Overcurrent faults are most common among various faults in the frequency converter. This fault is mostly caused by the following problems: First, as long as the inverter speeds up, it reports a fault, indicating that the overcurrent is very serious, mostly the load short circuit, mechanical parts are stuck, the inverter module is soft breakdown damage and the acceleration time is over. Shortly caused; secondly, the inverter reports a fault when it is powered, and it cannot be “reset” to be eliminated. Most of it is caused by damage to the internal drive circuit of the inverter and damage to the current detection circuit. The last phenomenon is the most extreme. When the power is turned on instantaneously or after a short delay, it directly causes the upper air to trip and the internal fuselage is blown out or sparks. The inverter rectifier unit and the power inverter component directly cause breakdown failure. Second, overvoltage
This type of fault phenomenon is also often found in inverter faults. In addition to eliminating the supply voltage is too high, there is also a case of such a fault – when the inverter is stopped. The main reason for this may be caused by a slow deceleration time or a problem with the braking resistor and the brake unit.
Third, under voltage
The above overvoltage fault corresponds to the undervoltage fault of the inverter. Generally, the power supply voltage is too low. It may also be caused by the following reasons: the power supply phase loss, the open circuit fault of one bridge arm of the rectifier circuit, and the main circuit If the capacity of the filter electrolytic capacitor becomes small or a problem occurs in the voltage detection circuit, the inverter may experience an undervoltage fault. In addition, if the internal snubber resistance of the inverter is not cut off by short circuit, an undervoltage fault will occur as long as the inverter is loaded.
Fourth, over temperature
Over-temperature is also a common fault of the inverter. This fault is mostly caused by the temperature of the inverter working environment is too high, the cooling holes are blocked, the cooling fan is damaged, the temperature sensor and the temperature detection circuit are damaged.
Through the above analysis of the four common faults of the inverter (of course, faults such as overload and output imbalance), it is not difficult for the peers to see that the inverter needs to work harder in daily maintenance, and more needs to be done in daily maintenance. We will use it flexibly according to the situation on the spot, and try our best to prevent it before it happens!

The influence of the carrier frequency of the inverter and the setting standard

  Most of the inverters are in the form of PWM modulation for the inverter. That is to say, the voltage output from the inverter is actually a series of pulses, and the width and interval of the pulses are not equal. Its size depends on the intersection of the modulated wave and the carrier, which is the switching frequency. The higher the switching frequency, the greater the number of pulses in a cycle, the better the smoothness of the current waveform, but the greater the interference to other devices. The lower the carrier frequency or the poor setting, the motor will make an unpleasant noise. By adjusting the switching frequency, the noise of the system can be minimized, the smoothness of the waveform is best, and interference can be minimized. 1. Overview of low frequency inverter carrier frequency

For inverters with voltage ≤500V, almost all of the main circuits of AC-DC-AC are used today. The control mode is sinusoidal pulse width modulation (SPWM). Its carrier frequency is adjustable, generally from 1~15kHz, which is convenient. Make artificial choices. However, in actual use, many users only follow the original set value of the inverter manufacturing unit, and do not adjust according to the actual situation on site. As a result, the carrier frequency value is improperly selected, which affects the correct effective working state. How to correctly select the carrier frequency value of the inverter during the use of the inverter is also important. This article provides considerations for the following aspects and as a basis for the correct selection of carrier frequency values.

2, carrier frequency and inverter power consumption

The power loss of the power module IGBT is related to the carrier frequency, and the carrier frequency is increased, the power loss is increased, such that the efficiency is reduced, and the second is that the power module generates heat, which is disadvantageous for long-term operation, of course, the inverter The higher the operating voltage, the greater the impact on power loss.

The larger the carrier frequency, the greater the loss of the inverter and the smaller the output power. If the ambient temperature is high, the dead zone of the upper and lower inverter tubes of the inverter bridge will become smaller during the alternate conduction process. In severe cases, the bridge arm may be short-circuited and damage the inverter.

3, carrier frequency and ambient temperature

When the frequency converter requires high carrier frequency and the ambient temperature is high, it is very unfavorable for the power module. At this time, the frequency of the carrier frequency of the different power inverters and the ambient temperature are used. The size and the allowable constant output current of the inverter should be appropriately reduced to ensure safe, reliable and long-term operation of the power module IGBT.

4, carrier frequency and motor power

If the motor power is large, the relative carrier frequency is lower. The purpose is to reduce the interference (the influence on the use of other devices) and reduce the power consumption and heat generation. Generally, this principle is followed, but the specific values ​​of different manufacturers are different.

5. The relationship between the carrier frequency and the length of the secondary output (U, V, W) of the inverter.

Generally, as the output line grows, the leakage current of the inverter will increase. Therefore, if the output line is long, the carrier frequency should be appropriately reduced.

Carrier frequency: 15kHz 10kHz 5kHz 1kHz

Line length: <50m>50~100m>100~150m>150~200m

11 benefits of using a frequency converter

There are many benefits to using a frequency converter:

1. First use a cage induction motor that is inexpensive and easy to maintain. Moreover, the original induction motor can be directly used without modifying the mechanical and drive system to improve the mechanical function.

2. Continuous, extensive operation is possible. When using the original common power supply, use another variable speed device (reducer, belt, etc.) for shifting. However, only phase shifting is possible and continuous shifting is not possible.

3. Inverter can replace DC engine, then use induction motor. Like the DC engine, it does not require a brush, slip-ring, etc., and is excellent in maintainability and environmental resistance.

4. The inverter can be soft-started and soft-closed to adjust the acceleration/deceleration time of the engine.

5. Reduce the starting current. Through the soft start and soft shutdown of the inverter, the starting current can be reduced to 1.5~2 times of the rated current when the motor starts. Generally, when the direct-in starts, the starting current of the current rated current is 6 times, so it will load the frequent running/stopping of the motor.

6. The inverter’s rebound brake facilitates electric braking.

7. One engine can be controlled in parallel with one inverter.

8. High efficiency.

9. Use inverters in ventilators, pumps, etc. to reduce energy; for air conditioning equipment, to create a comfortable environment.

10. It can perform high speed operation above the rated motor current.

11. Use the best speed control to improve quality.

Key points for judging the quality of inverter products

The technical grade of the frequency converter is gradually developed and formed. With the improvement of the use requirements and the development of technology, the quality of the device, the expansion of functions, and the advancement of automation technology are gradually advanced. Generally, the following ten points are generally considered in determining the quality of the product, as follows:
1, the control mode of the inverter
The control method is the first to determine the performance of the inverter, it depends on the software programming technology. With the advancement of the times and technological development, the inverter control methods are:

(1) V/f=C is an open loop control;
(2) SVPWM space voltage vector control, which is open loop control;
(3) Vector control VC, which is closed-loop control, with current I, magnetic flux φ, torque T, and rotational speed n; generally inner ring is φ, T, I, and outer ring is n (or w) .
(4) Direct Torque Control DTC is a closed-loop control. It can have 400% Te at n=0, the above four commonly used.

After 2000, there are inverters without feedback devices in foreign countries, that is, there is no need to install additional sensors or encoders, and the current, voltage, magnetic flux, and rotational speed changes of the inverter during operation are passed, and device devices such as detection and decoupling are fed back. See Figure 1, Table 1, and Table 2 for the input. Since its inception, it has been well received and favored by users. It is mainly convenient to use and functions as a frequency converter with speed sensor feedback device. At present, the control mode of high-voltage inverters is mostly A and B. No feedback device is in trial production, C is in development.

2. Unique control methods for several inverters
(1) Optimized PWM vector control
The sinusoidal pulse width modulation SPWM has the advantages of simple circuit and good linearity, but the output voltage is not high. The maximum linear output voltage amplitude is only /2=0.866 of the input voltage, which is essentially the phase voltage control method. The optimized PWM vector control mode adopts a dual modulation process, that is, the amplitude of the triangular wave phase and the modulation signal (0 to 50 Hz) are adjusted together to control the switching operation state of the IGBT by the switching angle α (30° to 60°) and modulation. Depth α = sine wave amplitude / triangle wave amplitude < 0.95. The characteristic is that the total harmonic current loss is small and the pulsation torque is small. When α=0.92~0.95, the harmonic loss is the smallest, especially when the carrier frequency is low, it can fully show its superiority, which shows that the output voltage is increased by about 20%, the harmonic is reduced, but the signal wave modulation depth is The linearity between the switch angle and the switch angle is affected. As the α increased voltage control becomes smaller, the total harmonic current distortion THD value is still small, so it is often used.
(2) PWM modulation method control
1 synchronous modulation
The number of triangular waves included in one modulation signal period is constant, and the carrier period is changed proportionally while changing the signal period, so that ≥3 and must be an odd number. When the switching frequency is low, the symmetry of the output waveform can be guaranteed, but at a lower frequency, the number of carriers appears sparse, resulting in an increase in the ripple of the current waveform, so it is only applicable to the frequency range of f>20Hz, the current This is the case with the V/F method.
2 asynchronous modulation
The carrier period remains unchanged while the modulation signal changes periodically. That is, the modulation characteristic is that the harmonic loss and the torque ripple are greatly improved during low frequency operation, and the f<20Hz low frequency working segment is applicable.
3 random modulation
According to the period of the modulation signal and the voltage value of the output, the modulation mode, the modulation depth a and the switching angle α can be automatically selected to adapt to the closed-loop system with large operating frequency variation amplitude, large load torque or power variation and impact. This modulation method fundamentally solves the shortcomings of SPWM in the low-frequency working segment, that is, the shortcomings of torque, torque ripple and harmonics. However, there are certain difficulties in software technology, and there is no such modulation method at home and abroad. The product. near
(3) Control according to the U-shaped characteristic curve of the motor and the V/f matching mode
According to the control method of the U characteristic curve of the motor and V/f, it is known that the V/f control is static voltage regulation, that is, when f is constant, the voltage is also fixed, and it is not according to the motor load factor β. For optimal control. Japan’s AREX company won the world-recognized super energy-saving controller 10 years ago. It has an additional link, which can automatically search (through ASIC) according to the actual load rate β, and output the minimum working voltage and minimum working current (U). Shape characteristic curve), therefore it is the most energy-saving, it can save 8%~10% more power than the general frequency converter under the same working conditions, and cos is a dynamic power adjustment controller, especially suitable for fans and pumps. . In the energy-saving operation, the effect is very good, the early products are SMX series. In recent years, in order to expand the scope of use, it is suitable for speed regulation, and the new variety is VMX series. Later, Hitachi J300 series inverters also have this function during energy-saving operation. The U-shaped characteristic curve of the motor is shown in Figure 2.
(4) Fuzzy control mode
Fuzzy control (FUZZY)
This method is controlled by the fuzzy control method according to the motor parameters and operating state, and is especially suitable for the application of the general-purpose single-chip microcomputer such as 8031 ​​as the CPU. The fuzzy control software simplifies the mathematical model, and can control the multi-variable real-time. The random variable can reach a certain precision. It is required to be widely used in household appliances such as refrigerators, air conditioners, washing machines, and microwave ovens. Of course, fuzzy control is also applicable to the control of the frequency converter. For example, the Vacon inverter uses fuzzy current vector control (see Figure 3).
(5) Self-tuning (motor parameter online measurement control)
(6) Recently, green harmonics have come out

Winter freeze protection of factory pipelines and countermeasures

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.

Injection molding machine, hydraulic press frequency conversion power saving transformation plan

First, the injection molding machine. Hydraulic machine power saving work introduction:
At present, the injection molding machine oil circuit used in China’s plastics industry uses proportional valve control technology and on-off valve control technology. The hydraulic power section uses the hydraulic system of a common three-phase asynchronous motor + metering pump. The molding process of the product is generally divided into several stages such as clamping, injection, melting, holding, cooling, mold opening and discharging;


Oil circuit features controlled by proportional valve:
After the operation of the oil pump motor, the full-speed and high-load operation, and then the proportional pressure to set the pressure and flow required for each stage of operation, while the injection molding machine in a production cycle, only the high-voltage mold clamping and melting stage motor load is large, other work The stage motor load is generally small. In other stages, the oil pump motor provides a constant flow at a constant speed, and excess hydraulic oil flows back through the overflow valve. Produce unnecessary waste.
Oil circuit features controlled by on-off valves:
The power of the oil pump motor is equipped according to the maximum load during its operation. After the operation of the oil pump motor, no pressure and flow settings are made. When working at various stages of clamping, injection, melting, holding, cooling, and mold opening, In the oil circuit, the switch valve is opened by the directional direction, the full flow is working, and the relief valve is closed. During the cooling and discharging, the direction switch of each stage is suffocated, the relief valve is opened, and all the recirculation is generated, resulting in waste.

Second, the injection molding machine. Oil-saving machine power-saving transformation analysis:
The hydraulic drive equipment represented by the injection molding machine has almost zero load during cooling and discharging, and the cooling and discharging time accounts for 3% to 6% of the entire cycle. Based on past work experience, in the injection molding machine. The energy loss caused by cooling and discharge overflow is as high as 30%-65%, and the power consumption of the injection pump oil pump motor accounts for 63%-75% of the total equipment power consumption. Great energy saving potential.

Third, the injection molding machine. Hydraulic pump power saving transformation principle:
Power saving retrofit solution with proportional valve control:
The flow rate Q of the injection pump is proportional to the pump speed n. As long as the speed of the pump motor is changed, the pump speed can be changed, thus changing the pump’s oil absorption. An economizer is added in front of the oil pump motor, and the speed signal of the economizer is taken from the driving signal of the proportional flow valve (0-1A), so that the output speed of the economizer is synchronized with the flow rate of the injection valve proportional flow valve. For example, the actuator requires 50% flow, and the economizer drives the motor (Ne=1500) to provide 750 rpm. The motor drives the pump to extract 50% of the flow from the cylinder. The part of the flow that does not extract the overflow will not cause unnecessary waste. During the special cooling and discharging process, the oil pump does not draw the flow from the cylinder at all, and the motor can be completely stopped without consuming electricity. It is in complete agreement with the whole process of the injection molding machine, and achieves high efficiency and energy saving without affecting production efficiency.

 

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