The electrical equipment that electric workers know the most should be the engine. Path.
So what are the differences between them?
1. The full pressure begins directly
When the capacity and load of the electrical network allow a complete direct voltage start -up, it is possible to consider using the direct start of the full voltage.
The advantages are that control is easy to use, simple to maintain and relatively economical. It is mainly used to start motors at small power.
2. Start of pressure reduction automatically coupled
Using the reduction in multiple pressure from the autotransformator can not only adapt to the start -up needs of different charges, but also obtain a higher starting torque.
Its greatest advantage is that its starting couple is important. And the starting torque can be adjusted by typing. It is still widely used today.
3. Y-Start
For a Asynchronous Squirrel Cage Asynchronous engine with a normal operation of a triangular connection method, if the stator winding is connected to a star shape during start -up, then connected to a triangle after starting, the current starting can be reduced and it can reduce the electrical network. impact.
This starting method is called decompression start of the star triangle, or simply called Star Triangle Start (Y-Start).
When you use Star Triangle to start, the starting current is only 1/3 of the original starting current according to the triangle connection method. If the starting current during direct starter is measured from 6 to 7ie, the starting current is only 2 to 2.3 times when the star triangle is started.
This means that when using the star triangle to start, the starting torque also falls 1/3 from the original direct starting according to the triangle connection method.
Suitable for situations where there is no load of load or light load. And compared to any other reduction starter of pressure, he has the simplest structure and the cheapest price. In addition, the Star Triangle Start method has another advantage, that is to say when the load is lighter, the engine can be executed under the Star connection method.
Currently, the nominal torque can be suitable for the load, which can improve the efficiency of the engine and thus save energy consumption.
4. Soft starter
This uses the principle of thyristor phase phase voltage regulation to carry out engine voltage regulation.
Due to the use of thyristor components, harmonic interference is important when the thyristor works, which has a certain impact on the electricity network.
In addition, the fluctuations of the electrical network will also affect the conduction of the components of the thyristor, in particular when there are several thyristor devices in the same electrical network.
Consequently, the failure rate of the components of the thyristor is higher, as power electronics technology is involved, so the requirements for maintenance technicians are also higher.
5.
The frequency converter is the engine control device with the highest technical content, the most complete control function and the best control effect in the field of modern engine control.
Because it involves electronics and microcomputer technology technology, the cost is high and the requirements for maintenance technicians are high.
Comparison of the advantages and disadvantages of starting decompression, the start of software and the start of frequency conversion
Beginning of decompression, the common star-triangle start-up is the start of the stars, the disadvantage is that the starting torque is small, and it is only suitable for start-up or light load. The advantage is that the price is cheap.
Starting depending on the start time and initial starting torque can be defined to get a start -up and a soft stop for the device, and can limit the starting current, and the price is moderate.
Frequency conversion begins gently depending on the time defined and allows the device to execute the defined frequency, which is relatively expensive.
Comparison of the principles of performance reduction in pressure starting, soft start and starting the variable frequency
1. The soft starter is a combination of the AC voltage regulation technology of the thyristor and the power factor control technology.
2. The frequency converter is a motor control device (speed regulation) which uses the power effect of the power semiconductor to convert the power supply to another frequency. The control of the engine operation by a variable frequency (the voltage also changes with the frequency, such as the V / F constant), is a really effective way to regulate the speed and is very effective. The frequency converter can obtain a real soft start, gentle stop and effective speed regulation.
3. The current pressure reduction methods are two types: starting automatic decompression and the start of Y-Mouch. The couple can reach 64% of direct start. And the starting torque can be adjusted by typing. It is still widely used today.
Y-sac is suitable for situations where there is no load of load or light load. And compared to any other reduction starter of pressure, he has the simplest structure and the cheapest price.
In addition, the Star Triangle Start method has another advantage, that is to say when the load is lighter, the engine can be executed under the Star connection method.
Currently, the nominal torque can be suitable for the load, which can improve the efficiency of the engine and thus save energy consumption.
Complete analysis of reduction in pressure starting, software starting and frequency conversion starting
1. Price problems
Naturally, the frequency converter is the most expensive, and Y-G. and the automatic decompression start is relatively cheap. For projects with smaller investments, the economy will become the first choice.
2. Controllable problems
Y-sac, automatic decompression starts simple, but it starts. However, in situations with high automation, it is estimated that it will be less used and even less at start -up. The engine control through the inverter, including speed, voltage, etc., is far beyond the range of starting and starting of decompression.
Therefore, frequency converters are the first choice for large or highly automated production lines.
3. Network communication
The inverter itself can monitor the network via its own integrated or extended communication port. Soft Start can also make a certain surveillance, but real -time monitoring of the engine is incomparable to the reduction in pressure and smooth start -ups.
4. Maintenance
Since Y-δ and automatic decompression are relatively simple, they are naturally the simplest to maintain. I am actually very opposed to the use of soft start.
The inverter can obtain the soft start and the mild engine stop, therefore in relatively large load situations, Y-δ, automatic start or mild start are not as good as the inverter.
Complementary comparison of knowledge
1. Soft start -up and frequency converter
The inverters and gentle start -up devices belong to the category of interrupted startups.
Soft Start is a starting process from voltage 0 to complete tension by modifying the angle of the thyristor.
The frequency converter is controlled throughout the process, and the engine speed can be controlled by the instrument signal at any time.
2. A comparison of the engine starting method
Common methods for start-up engines: direct voltage starting, automatic start-breakdown, y- start-up, soft start, frequency conversion starting, etc.
When the electrical network and the load allow it, it is preferable to start the engine directly because operation and control are practical and economical.
The automatic start of decompression is often used to start an asynchronous engine with squirrel cage plus capacity. For start -up, it is to obtain a higher starting torque, and it is widely used due to the installation of thermal relays and low voltage travel, which have complete overload and loss of protection against pressure .
The Star Triangle Start mode has good current characteristics and bad torque characteristics, it is therefore only suitable for situations where there is no load of load or light load. Operation of the light load.
The above start-up methods are all the decompression departures staged and have obvious drawbacks, namely, the secondary shock current occurs during the starting process.
3. Comparison of mild start with the traditional start of pressure reduction
① No impact current
When the soft starter starts the engine, the engine starting current increases zero to the defined value by gradually increasing the conduction angle of the thyristor. It has no impact on the engine, improves the reliability of the power supply, smooth start -ups, reduces the impact torque on charging machines and extends the life of the machine.
② It has a soft parking function
In other words, gentle deceleration and gradual stop.
③ The starting parameters are adjustable
Depending on the load condition and the gear protection characteristics of the grid, the optimal starting current can be adjusted without step.
The starter and the frequency converter are two completely different products. Start-up.
The inverter has all the gentle start -up functions, but it is much more expensive than the soft starter and has a much more complex structure.
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