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| Inverters FAQ |
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| Industry News > Add time:2008/1/28 |
1, what is the frequency converter?
Inverter is the use of power semiconductor devices will be the role of on-off frequency to another frequency power transformation of the power control devices.
2, PWM and PAM What is the difference?
PWM is English Pulse Width Modulation (PWM) initials, according to a certain law of the change in pulse width pulse, and to regulate the output waveform for a value approach. PAM is English Pulse Amplitude Modulation (pulse amplitude modulation) initials, according to a certain law of the change in pulse amplitude pulse, in order to regulate the output waveform of money and a modulation mode.
3, voltage and current-what's the difference?
Inverter main circuit generally can be divided into two categories: voltage is to transform DC voltage source for the exchange of inverters, DC circuit filter is capacitance; Current is to transform the DC current source for the exchange of the inverter the DC circuit filter inductor stone.
4, why the inverter voltage and current proportional to the change?
Non-synchronous motor torque of the motor rotor flux and flow within the current interaction between the product of the rated frequency, but only if we reduce the voltage frequency, then the magnetic flux on too large, magnetic circuit saturation, serious motor will be destroyed. Therefore, the frequency and voltage proportional to change, that is, change the frequency of the converter output voltage control, so that motor flux maintain a certain avoid weak magnetic phenomena and the formation of magnetic saturation. This control method used for fans, pumps, power-converter.
5, the use of the frequency motor drive power, voltage drop, current increase in the inverter drive, if declining frequency voltage drop, then the current rise?
Frequency decreased (Low), and if the same power output, the current increase, but in torque under certain conditions, the current almost unchanged.
6, using inverter operation, the motor starting current, starting torque?
Using inverter operation, with a corresponding increase in the acceleration of motor frequency and voltage starting current is limited to 150% of rated current below (under different machine, 125% ~ 200%). Starting direct labor-frequency power supply, starting current of 6 to 7 times, therefore, it will have the impact on the electrical machinery. Inverter Drive can be used to smooth start (starting time variable length). Starting current rated current of 1.2 to 1.5 times the starting torque of 70% to 120% of rated torque, with the enhancements of automatic torque converter, the starting torque of 100 percent and above, can bring Starting full load.
7, V / f mode What does that mean?
Frequency, voltage drop proportional to V also declined, this issue has been answered in the note 4. V and f is to consider the ratio between the electrical characteristics of the decision in advance, usually in the controller storage devices (ROM), there are several characteristics can be used to switch or scaling set to choose.
8, in proportion to the change of V and f, motor torque to change?
Frequency decreased in proportion to completely reduce voltage, AC impedance change due to the small and DC resistance unchanged, would result in low-speed torque is produced to reduce the tendency. Therefore, when given in low V / f, to raise some of the output voltage, in order to obtain a certain starting torque, such that enhanced compensation starter. Can be used to achieve various methods, the method automatically, select V / f mode or adjust potentiometers, and other methods.
9, in the statement read speed of 60 Hz ~ 6, 10:1, in the following 6 Hz output power not?
Still below 6 Hz output power, but under the motor starting torque and temperature conditions, such as the size of the minimum frequency of use from about 6 Hz, output at the rated torque motor and the heat will not cause serious problems. Actual output frequency converter (starting frequency) aircraft for 0.5 to 3 Hz.
10, the general motor combination is at 60 Hz and above also requires a certain torque, can it be?
Under normal circumstances, no. Above 60 Hz (50 Hz also above mode) the same voltage, constant power for the general characteristics required under the same high-speed torque, it should be noted motor and inverter capacity choice.
11, the so-called open-loop What does that mean?
To the use of a motor speed detection devices (PG), the actual speed feedback control to the control device, known as "closed-loop", not on the operation of the PG called "open-loop." Universal Converter mostly open-loop, and some models can be used option PG feedback.
12, the actual speed for a given speed deviation how do?
Open-loop, even if the inverter output given frequency band in the motor load operation, motor speed rated slip in the context of (1% ~ 5%) changes. Accuracy requirements for the relatively high speed, even if the load in the past also requires changes in a given speed operation of the occasion, PG feedback can be a function of frequency converter (Optional items).
13, a PG If the motor, feedback can improve the accuracy rate?
PG feedback function with the inverter, the accuracy has improved. But the speed depends on the accuracy of implant PG own inverter output frequency accuracy and resolution. 14, Stall function to prevent what is the meaning?
If given the acceleration of time is too short, the output frequency converter far exceeded the speed changes (Xinhua angular frequency) changes will be due to flow inverter overcurrent and tripping, stop functioning, which called stall. In order to prevent continued to stall the motor running, it is necessary to carry out the size of current detection frequency control. When excessive speed up the current accelerated rate due to slow down. The same is true when the slowdown. Stalling is combining these two functions.
15, and the slowdown is accelerating time to time can be set for each species, and processing deceleration time to set common aircraft types, which is what is the point?
Acceleration and deceleration can be set to different kinds of machines, for a short period of time to accelerate, slow deceleration occasions, or for small machine production will need to beat strict time it is appropriate to the occasion, but for the fan drive, and so on, acceleration and deceleration time longer acceleration and deceleration time to be common.
16, what is the regenerative braking?
If the motor in operation in order to reduce the frequency, the motor into a state of non-synchronous generator running, as a brake work, which called renewable (Electrical) braking.
17, the system can be more dynamic?
Motor out from renewable energy storage capacitor filter in the converter, because of the capacitor capacity and the relationship between the pressure
What is the frequency converter?
Inverter is the use of power semiconductor devices will be the role of on-off frequency to another frequency power transformation of the power control devices.
2, PWM and PAM What is the difference?
PWM is English Pulse Width Modulation (PWM) initials, according to a certain law of the change in pulse width pulse, and to regulate the output waveform for a value approach. PAM is English Pulse Amplitude Modulation (pulse amplitude modulation) initials, according to a certain law of the change in pulse amplitude pulse, in order to regulate the output waveform of money and a modulation mode.
3, voltage and current-what's the difference?
Inverter main circuit generally can be divided into two categories: voltage is to transform DC voltage source for the exchange of inverters, DC circuit filter is capacitance; Current is to transform the DC current source for the exchange of the inverter the DC circuit filter inductor stone.
4, why the inverter voltage and current proportional to the change?
Non-synchronous motor torque of the motor rotor flux and flow within the current interaction between the product of the rated frequency, but only if we reduce the voltage frequency, then the magnetic flux on too large, magnetic circuit saturation, serious motor will be destroyed. Therefore, the frequency and voltage proportional to change, that is, change the frequency of the converter output voltage control, so that motor flux maintain a certain avoid weak magnetic phenomena and the formation of magnetic saturation. This control method used for fans, pumps, power-converter.
5, the use of the frequency motor drive power, voltage drop, current increase in the inverter drive, if declining frequency voltage drop, then the current rise?
Frequency decreased (Low), and if the same power output, the current increase, but in torque under certain conditions, the current almost unchanged.
6, using inverter operation, the motor starting current, starting torque?
Using inverter operation, with a corresponding increase in the acceleration of motor frequency and voltage starting current is limited to 150% of rated current below (under different machine, 125% ~ 200%). Starting direct labor-frequency power supply, starting current of 6 to 7 times, therefore, it will have the impact on the electrical machinery. Inverter Drive can be used to smooth start (starting time variable length). Starting current rated current of 1.2 to 1.5 times the starting torque of 70% to 120% of rated torque, with the enhancements of automatic torque converter, the starting torque of 100 percent and above, can bring Starting full load.
7, V / f mode What does that mean?
Frequency, voltage drop proportional to V also declined, this issue has been answered in the note 4. V and f is to consider the ratio between the electrical characteristics of the decision in advance, usually in the controller storage devices (ROM), there are several characteristics can be used to switch or scaling set to choose.
8, in proportion to the change of V and f, motor torque to change?
Frequency decreased in proportion to completely reduce voltage, AC impedance change due to the small and DC resistance unchanged, would result in low-speed torque is produced to reduce the tendency. Therefore, when given in low V / f, to raise some of the output voltage, in order to obtain a certain starting torque, such that enhanced compensation starter. Can be used to achieve various methods, the method automatically, select V / f mode or adjust potentiometers, and other methods.
9, in the statement read speed of 60 Hz ~ 6, 10:1, in the following 6 Hz output power not?
Still below 6 Hz output power, but under the motor starting torque and temperature conditions, such as the size of the minimum frequency of use from about 6 Hz, output at the rated torque motor and the heat will not cause serious problems. Actual output frequency converter (starting frequency) aircraft for 0.5 to 3 Hz.
10, the general motor combination is at 60 Hz and above also requires a certain torque, can it be?
Under normal circumstances, no. Above 60 Hz (50 Hz also above mode) the same voltage, constant power for the general characteristics required under the same high-speed torque, it should be noted motor and inverter capacity choice.
11, the so-called open-loop What does that mean?
To the use of a motor speed detection devices (PG), the actual speed feedback control to the control device, known as "closed-loop", not on the operation of the PG called "open-loop." Universal Converter mostly open-loop, and some models can be used option PG feedback.
12, the actual speed for a given speed deviation how do?
Open-loop, even if the inverter output given frequency band in the motor load operation, motor speed rated slip in the context of (1% ~ 5%) changes. Accuracy requirements for the relatively high speed, even if the load in the past also requires changes in a given speed operation of the occasion, PG feedback can be a function of frequency converter (Optional items).
13, a PG If the motor, feedback can improve the accuracy rate?
PG feedback function with the inverter, the accuracy has improved. But the speed depends on the accuracy of implant PG own inverter output frequency accuracy and resolution. 14, Stall function to prevent what is the meaning?
If given the acceleration of time is too short, the output frequency converter far exceeded the speed changes (Xinhua angular frequency) changes will be due to flow inverter overcurrent and tripping, stop functioning, which called stall. In order to prevent continued to stall the motor running, it is necessary to carry out the size of current detection frequency control. When excessive speed up the current accelerated rate due to slow down. The same is true when the slowdown. Stalling is combining these two functions.
15, and the slowdown is accelerating time to time can be set for each species, and processing deceleration time to set common aircraft types, which is what is the point?
Acceleration and deceleration can be set to different kinds of machines, for a short period of time to accelerate, slow deceleration occasions, or for small machine production will need to beat strict time it is appropriate to the occasion, but for the fan drive, and so on, acceleration and deceleration time longer acceleration and deceleration time to be common.
16, what is the regenerative braking?
If the motor in operation in order to reduce the frequency, the motor into a state of non-synchronous generator running, as a brake work, which called renewable (Electrical) braking.
17, the system can be more dynamic?
Motor out from renewable energy storage capacitor filter in the converter, because of the capacitor capacity and the relationship between the pressure
18, please indicate the inverter protection?
Protection can be divided into the following two categories:
(1) found that after the abnormal state of the amendment moves automatically, such as the current stall prevention, renewable stall to prevent over-voltage.
(2) anomaly that seized power after the blockade PWM control signal semiconductor devices, motor automatic parking. If the current cut, cut renewable overvoltage, semiconductor cooling fan overheated and instantaneous power failure protection.
Asked some basic questions, and you ask for advice
1. Inverters to the motor is general or specific frequency electrical motor
2, if the next general motors that can access variable frequency inverter motor?
3, variable frequency electrical power can be directly received on?
4, the frequency of changes in the scope of how many ah
[Answer]
FM technology to the requirements of motor mainly in three aspects:
First, the insulation levels;
Second, the mandatory cooling;
Thirdly, the rotor.
If more than baseband progressive governor, we must also consider the electrical structure of mechanical strength. Generally, will replace ordinary electrical motor FM, a radio transmission. From the principle that the trip. From the actual products that may firms may not. That is not reliable. Now foreign brands have all the electrical, domestic also points, but some famous domestic motor manufacturers have been to ordinary motor insulation rating has been raised to "F" grade. Hoyzer is that this is the equivalent of Class F Class F. Is not the real significance of the Class F insulation. The aim is to motor to adapt to the inverter control applications. Therefore, it can not be a substitute to ordinary motor inverter motor, or look at the key motor manufacturer's technical condition is not met variable frequency control requirements. Not generalize to say YES or NO.
Ordinary asynchronous motors are in constant frequency constant pressure design, and it is impossible to completely meet the requirements of VVVF. Following is the impact of motor inverter
1, the motor temperature and the efficiency of the problem
Regardless of the type of converter, both in the operation of a different degree of harmonic voltage and current so that the motor in the non-sinusoidal voltage, current running. Resist materials, the current widespread use of the sine wave PWM converter for example, low harmonic basic zero, the remaining carrier frequency than twice around the high harmonic components: 2 u +1 (for u Modulation ratio). High-order harmonic generation will cause copper consumption of motor stator and rotor copper (Al) consumption, the consumption of iron and additional wear and tear increase, the most notable is the rotor copper (Al) consumption. Because asynchronous motor is closer to the fundamental frequency of the corresponding synchronous speed rotation and, therefore, high harmonic voltage to the larger deterioration of the lead after cutting rotor, rotor will be a great loss. In addition, the need to consider skin effect generated by the additional copper consumption. These losses will make additional motor fever, reduced productivity, reduced output, such as the ordinary three-phase asynchronous motor running on the non-sinusoidal output inverter power supply conditions, the average temperature increased by 10% - 20%.
2, the motor insulation Strength
At present small and medium-sized inverter, using many of the PWM control mode. He is the carrier frequency of thousands to more than 10 kHz, which makes motor stator windings have to bear the high rate of increase in the voltage, the equivalent of the motor exert a great impact on the steep voltage, the motor interturn insulation under more harsh test. In addition, the PWM converter from the rectangular stack Chopper impulse voltage to the motor operating voltage, the motor insulation would pose a threat to the high-voltage insulation in the repeated impact will be accelerated aging.
3, harmonic electromagnetic noise and vibration
General use asynchronous motor inverter power supply, will by the electromagnetic, mechanical, ventilation caused by factors such as vibration and noise becomes more complex. Frequency Power in the presence of harmonics at the time and part of the electromagnetic motor inherent space harmonic interference in each other, forming various electromagnetic excitation. When the frequency of the electromagnetic wave in the body of the motor and the inherent vibration frequency identical or close to, will have a resonance phenomenon, thereby increasing noise. As motor operating frequency range, speed of the changes, all of the electromagnetic wave frequency of the motor it is difficult to avoid the inherent vibration frequency components.
4, the motor frequently activated brake adaptability
As a power inverter, the motor can be in the low frequency and voltage to a current impact initiate, and the use of inverter for the various methods for rapid braking brake for the realization of frequent start-up and system Dynamic creation of the conditions, so the mechanical systems and electrical systems in the electromagnetic alternating cycle of the role, structure and mechanical insulation to bring about structural fatigue and accelerated ageing. 5, the low-speed cooling issues
First, the induction motor impedance less than ideal, when compared at the end of the frequency of power supply, power supply, high harmonics caused by the loss larger. Secondly, ordinary asynchronous motors to reduce speed, cooling air flow and speed of the three Bang ratio decreases, the resulting low-speed motor cooling conditions deteriorate, the temperature increased dramatically, it is difficult to achieve constant torque output.
Second, the characteristics of variable frequency motor
1, Electromagnetic Design
The general induction motor, the main consideration to the design of the performance parameters are Guozainaili, launch performance, efficiency and power factor. And variable frequency motor, as critical to the gap in inverse power frequency can be close to the critical slip directly 1:00 start, therefore, Guozainaili and need not start paying too much attention to performance, and to resolve the key issues is how to improve the motor non-sinusoidal power adaptability. General as follows: 1) reduce as much as possible the stator and rotor resistance. Stator resistance can be reduced to reduce the fundamental copper consumption, to make up for the high harmonics caused by copper consumption by 2) to curb the current high harmonics, and the need to appropriately increase the motor inductance. But larger rotor slot leakage reactance their skin effect are also great, high harmonics copper consumption also increased. Therefore, the size of electrical leakage reactance to take account of the speed of impedance matching is reasonable. 3) Frequency General Motor's main magnetic saturation is not designed to, first, consider the high harmonics of magnetic saturation will be deepened, and the second is considered low, in order to improve and to increase the output torque converter output voltage.
2, structural design
Further structural design, the main consideration is non-sinusoidal power characteristics of the variable frequency electrical insulation structure, vibration, noise, such as the cooling effect of general attention to the following questions: 1) Insulation class, generally Class F or higher, to strengthen Insulation fault lines and dielectric strength, in particular to consider impact resistant insulation voltage capability. 2) motor vibration, noise problems, we should give full consideration motor components and the overall rigidity of efforts to enhance its natural frequency to avoid with the wave of resonant phenomena. 3) cooling: the general use of forced ventilation cooling, that is the main motor cooling fan motor drive using independent. 4) Current measures to prevent the shaft of the motor capacity of more than 160 KW bearing insulation measures should be adopted. Is easy to produce asymmetric magnetic circuit will produce axial currents, when other high-frequency component of the current generated by the combination of role, Shaft Current will be greatly increased, resulting in damage to bearings, it is generally insulation measures to be taken. 5) constant power inverter motor, when speed over 3,000 / min should be used in the special high temperature grease to compensate for the rising temperature of bearings.
Frequency 0.1 HZ in the motor - 130HZ of long-term operation,
General Motors can be: 2 pole for the 20 - 65 hz of the long-term operation.
4-pole for the 25 - 75 hz of the long-term operation.
6 pole for the 30 - 85 hz of the long-term operation.
8 for a 35 - 100 hz of the long-term operation.
1, the motor temperature and the efficiency of the problem
Regardless of the type of converter, both in the operation of a different degree of harmonic voltage and current so that the motor in the non-sinusoidal voltage, current running. Resist materials, the current widespread use of the sine wave PWM converter for example, low harmonic basic zero, the remaining carrier frequency than twice around the high harmonic components: 2 u +1 (for u Modulation ratio). High-order harmonic generation will cause copper consumption of motor stator and rotor copper (Al) consumption, the consumption of iron and additional wear and tear increase, the most notable is the rotor copper (Al) consumption. Because asynchronous motor is closer to the fundamental frequency of the corresponding synchronous speed rotation and, therefore, high harmonic voltage to the larger deterioration of the lead after cutting rotor, rotor will be a great loss. In addition, the need to consider skin effect generated by the additional copper consumption. These losses will make additional motor fever, reduced productivity, reduced output, such as the ordinary three-phase asynchronous motor running on the non-sinusoidal output inverter power supply conditions, the average temperature increased by 10% - 20%.
2, the motor insulation Strength
1. Inverters to the motor is general or specific frequency electrical motor -------- can generally received more than ordinary motor.
2, if the next general motor inverter that can be then? ----------- Inverter motor can be.
3, variable frequency electrical power can be directly received on? ------------------------ Can, then another fan, but the Dacaixiaoyong.
4, the frequency of changes in the scope of how many ah ------------------------------ If you ask the changes in the frequency of the converter HZ general scope of 0-400,
If you ask the changes in the frequency of inverter motor, it is not the same as different motors, bearings and other machinery is the main aspect.
Frequency of occasions, triggering the application of electrical equipment for speed constantly changing;
Soft-start their application occasions for electrical equipment just to avoid the commencement of start-up current requirements.
Soft Start will be activated when starting torque is decreased, and cross converter start torque can be activated
Inverter capacity calculation and choice
Using asynchronous motor speed inverter drive. In the induction motor is confirmed, should normally be under the asynchronous motor rated current converter to choose, or in accordance with the actual operation of the induction motor's current (maximum) to select inverter. When not at the same time operation mode, the method of calculating capacity inverter and choose different methods, the drive should not meet the conditions of the same. Select inverter capacity, the drive is rated current is a key volume, the capacity inverter should be possible in the operation of the maximum current to choose. There is generally a converter operating in a number of ways.
2 continuous operation of the inverter capacity required for the calculation of
The converter is the transmission pulse motor current, fluctuating value than its frequency to the power supply at the current, the inverter capacity should be adequate cushion left. At this point, Drives should meet the following three conditions:
Where: PM, η, cos φ, UM, IM for motor output power, efficiency (from 0.85), power factor (from 0.75), voltage (V), current (A).
K: The current waveform correction coefficient (PWM mode from 1.05 to 1.1)
PCN: Inverter rated capacity (KVA)
ICN: Inverter rated current (A)
IM-such as in the actual operation of the motor by the maximum current to select inverter, the drive capacity can be appropriately reduced.
3 + deceleration capacity inverter choice
The maximum output torque converter is the largest converter output current decision. Under normal circumstances, for the short term in terms of acceleration and deceleration, to allow inverter rated output current of 130% to 150% (depending on frequency converter capacity), therefore, short-term increase in the deceleration of output torque can be increased; Instead , as only small increases decelerating torque, it may choose to reduce inverter capacity. As the pulse of current reasons, this should be the biggest inverter output current 10 per cent reduction can be carried out later selected.
4 frequent acceleration and deceleration inverter operation, the capacity of selected
Under acceleration, constant speed, deceleration, and other operations under the current state of the value-pressed to determine:
I1CN = [(I1t1 + + I5t5… I2t2 +) / (t1 + t2 +… t5)] K0
Where: I1CN: Inverter rated output current (A)
I1, I2,… I5: The average current state of operation (A)
T1, t2,… t5: running all the time
K0: security coefficient (from 1.2 when running frequent, and other conditions for the 1.1)
5 a multi-motor drive inverter, and the parallel operation of multiple motors, drive top group
With a frequency converter to operate parallel multi-motor, a small part of the starter motor start, and then an additional motor starter into other occasions, when the inverter voltage, frequency has been increased, additional input will produce motors great starting current, therefore, capacity and inverter starting at the same time when compared to the needs of these.
Short-term Guozainaili converter to 150%, 1 min converter as an example of the capacity at this time if the motor acceleration time in 1 min, the two should meet the following -
If the motor to accelerate when more than 1 mn
Where: nT: Parallel Motor Number
Ns: Starting at the same time the number of Taiwan
PCN1: continuous capacity (KVA) PCN1 = KPMnT / η cos
PM: motor output
Η: motor efficiency (from 0.85)
Cos φ: motor power factor (regular admission 0.75)
Ks: motor starting current / motor rated current
IM: motor rated current
K: current waveform is coefficient (PWM mode from 1.05 to 1.10)
PCN: inverter capacity (KVA)
ICN: Inverter rated current (A)
Multiple motor inverter drives, but which may have a motor attached to the converter at any time or at any time withdraw from the operation. At the rated output current of the inverter can be Anxiashijisuan:
Where: IICN: Inverter rated output current (A)
IMN: motor rated input current (A)
IMQ: The biggest one motor starting current (A)
K: security coefficient, 1.05 ~ 1.10 general admission
J: few remaining motor -
6 starter motor inverter capacity required for the calculation of
Usually, three-phase asynchronous motor starter when the frequency of direct employment for the rated current starting current of 5 to 7 times, the motor power of less than 10 kW of direct motor starter, can be selected by pressing-type converter.
I1CN ≥ IK / Kg
Where: IK: rated voltage, rated frequency of the motor starting block to the current (A);
Kg: Inverter Overload allows multiple Kg = 1.3 ~ 1.5
In the operation, such as motor current irregular changes in this difficult operating characteristic curve was, when will the motor torque output at the current maximum limit of the rated output current converter within selected.
7 starting at the high inertia loads calculation capacity inverter
Through the inverter capacity usually contains more than 125%, 150% or 60 s, 60 s. Need more than the value of the overload capacity, we must increase the capacity inverter. Under such circumstances, the capacity of general Anxiashijisuan converter:
Where: GD2: conversion to the motor shaft rotational inertia money (N • m2)
TL: load torque (N • m)
Η, cos φ, nM respectively motor efficiency (from 0.85), power factor (from 0.75), the rated speed (r / min).
TA: motor acceleration time (s) from the requirement of the load
K: The current waveform correction coefficient (PWM mode from 1.05 to 1.10)
PCN: Inverter rated capacity (KVA)
8 light-load motor inverter when the choice
Motor load than the actual motor is rated output power hours, believe that the option is commensurate with the actual load capacity inverter, but the general inverter, even if the actual load small, the use of electrical power ratings than by the choice of the capacity of the frequency converter - is not ideal, this was mainly due to the following reasons;
1) Motor also in the empty flow rated current 30% to 50% of the excitation current.
2) Starting at the current flowing through the motor starter imposed by the voltage, frequency relative, and that has nothing to do with the load torque, if the capacity of small converter, the current flow exceeds capacity, are often not start.
3) electrical capacity, while capacity-based converter
Inverters and energy saving, frequency, which is more economy?
I wonder if your load is not stable, if unstable, and I think you should use a good inverter control.
If the pumps work in the state rated, energy converter is basically no effect. Only in light-load conditions, the pump can not stop, constant pressure water supply, energy conservation is possible.
Inverters are elected by the pumps, pump work in the light-load conditions. A new energy-saving mode converter, when the load variable hours, automatic voltage reduction to energy saving effect.
Energy conservation, according to my experience, unless the maker of products, most of which are small factories bragging.
Soft Starter Set is a soft start motor, soft parking, and a variety of energy-saving light-load protection function in the new integrated motor control devices, called Soft Starter abroad. Its main components are connected in series to power and was charged with three motor contrast between the parallel gates and electronic control circuitry. Use different methods to control three of the gate opposite parallel conduction angle, was charged with motor input voltage according to different requirements change, we can achieve different functions. Soft Starter and inverters are two entirely different uses of products. Inverters are used for the needs of the local governor, not only changing its output voltage and frequency changes at the same time; soft starter is actually a regulator for motor starting, the only change in the output voltage and frequency did not change. Inverters have all soft start function, but it is cheaper than the soft starter much more expensive, much more complex structure.
At the same time change the inverter output voltage and frequency, which is changing the motor running on the curve n0, the motor running parallel downward curve. Therefore converter can make to a smaller motor starting current, motor starting torque at the same time to reach its maximum torque converter that can be activated Heavy load.
Soft-start only change the output voltage, frequency change is not to change the motor running on n0 curve, but to intensify the steepness of the curve, so that the electrical characteristics of soft. When n0 unchanged, all torque motor (rated torque, the most torque, stall torque) are proportional to the square of its terminal voltage, and therefore greatly reduced with soft-start motor starting torque, and soft-start does not apply to heavy-duty motor started.
VVVF technology in the fans, pumps in the application of energy-saving
In the industrial production and the manufacturing of products, fans, pumps a wide range of equipment; and its power consumption, such as valves, baffles the throttle loss related equipment, as well as maintenance, repair costs account for the cost of production of 7% to 25% , a small fortune in production costs and expenses. Along with the continuous deepening of economic reform, the growing competition in the market; saving energy has become a lower production costs, improve product quality one of the important means.
And the early 1980s development of the VVVF technology, precisely conforms to the development of industrial production automation requirements, has created a new era of Intelligent Motor. General Motors can only be changed to the running speed of the old model, and makes motor drag load without any changes in circumstances that can be adjusted in accordance with the requirements of the production process speed output, thereby reducing the electrical power system to achieve the purpose of efficient operation.
The late 1980s, the introduction of the technology in China and be replicated. Has been in power, metallurgical, petroleum, chemicals, paper, food, textile, and other industries in the electrical transmission equipment practical application. At present, the VVVF technology has become a modern electricity transmission technology one of the main direction of development. Speed outstanding performance, a significant energy saving effect of the operation of existing equipment to improve working conditions, improve the safety and reliability of systems and equipment utilization, extending equipment life with the advantages of applications continues to expand and is fully expressed .
Second, review
Usually in industrial production, product processing and manufacturing equipment used in the fan boiler combustion system, drying system, cooling system, ventilation system, and so on, according to the needs of production on the furnace pressure, wind speed, air flow, temperature and other indicators of control and adjust to adapt to technological requirements and operating conditions. The most common means of control is to regulate the throttle, baffle opening to adjust the size of the controlled object. In this way, regardless of the needs of production size, fan should operate at full speed, and operating status of the energy to make changes in the throttle, the throttle loss baffle have been lost. In the production process, not only limited control precision, but also a large amount of energy waste and equipment wear and tear. Resulting in increased production costs and shorten the life of equipment, equipment maintenance, maintenance costs, remains high.
Pump equipment in the manufacturing sector also has a broad application of space, to water pumping stations, water storage tank to the drainage system, industrial water (oil) circulatory system and heat exchange systems using centrifugal pumps, axial flow pump, gear pumps, piston pump , and other equipment. Furthermore, according to different production needs are often used adjustment valve, reflux valve, valve and other equipment expenditure flow, pressure and level control signal. This not only creates a lot of waste of energy, pipelines, valves and other sealing property damage, but also accelerated the cavity pump, valve wear and cavitation, serious damage to equipment, affecting production, threatening the quality of products.
Fans, pumps most equipment used directly driven asynchronous motor running, there starting current, mechanical shock, the electrical characteristics of poor protection shortcomings. Not only affect equipment life, but when the load when a mechanical failure can not instantaneous movement of protective equipment, often at the same time a damaged pump motors were also burned phenomenon.
In recent years, the urgent need for energy conservation and the continual improvement of product quality requirements, and the use of Frequency Converter (converter) easy to operate, maintenance-free, high-precision control, and can achieve high functional characteristics; so that the Inverter-driven start of the programme to gradually replace the throttle, baffle, valve control programme. |
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