Schneider inverter agent said the selection principle of the inverter
Schneider Inverter Agent Shanghai Kuanying Automation talks about the selection of the inverter In principle, the company is an internationally renowned high-tech enterprise, which is affiliated to the high-tech enterprise under the Kuanying Group. Now, with its solid strength and rapid development speed, Shanghai Kuanying Automation Equipment has become the vanguard of the industrial control industry.
Considering the economics and safety of the inverter operation, it is necessary to save the appropriate margin for the inverter selection.
To accurately select the type, it is necessary to master the following guidelines:
Fully understand the functional requirements of the control target. Generally speaking, if the requirements for starting torque, speed regulation accuracy and speed regulation range are high, you need to consider the use of vector inverter, otherwise you can use general-purpose inverter to understand the load characteristics, such as general occasions. , you need to determine whether the inverter is G-type or P-type
Know the first nameplate parameters of the motor used: extra voltage, extra current
Determine the possible large current of the load, so The current acts as an additional current for the drive to be selected. If the current is less than the additional current of the matching motor, select the corresponding inverter according to the matching motor, and consider the cost element.
The following conditions should consider the capacity amplification:
1. Long-term high temperature Heavy load
2, abnormal or downtime will have catastrophic consequences on the scene
3, the target load fluctuates greatly
4, the field grid is low for a long time Load is close to extra
5. Winding motor, synchronous motor or multi-pole motor (6 or more poles)
About inverter selection For accessories, it is necessary to master the following guidelines:
Communication input reactors and DC reactors should be used in the following situations:
Civil occasions, such as: hotel central air conditioning, motor power More than 55KW
Poor grid quality or small capacity
If not selected, it may cause disturbance, large current deviation of three-phase current, frequent inverter frying machine< p=""> Communicate the output reactor with the following conditions
The inverter to the motor line exceeds 100 meters (general guidelines)
Braking unit and braking resistor are generally selected in the following conditions
Frequent rapid acceleration/deceleration
Large inertia (free parking requirement for more than 1 min) The device whose constant speed running current is less than the accelerating current)
The energy saving of the inverter is mainly manifested in the operation of the fan and the water pump. In order to ensure the reliability of production, all kinds of production machinery have a certain margin when planning the power drive. When the motor is not able to operate at full load, in addition to reaching the power drive requirements, the remaining torque increases the cost of active power, resulting in wasted power. Fans, pumps and other equipment traditional speed control method is to adjust the inlet or outlet baffle, valve opening to adjust the air volume and water supply, the input power is large, and a lot of energy consumption in the baffle, valve interception process in. When using variable frequency speed regulation, if the flow demand is reduced, the speed of the descending pump or fan can meet the requirements.
The role of the inverter in the motor is to regulate the speed and reduce the starting current. In order to generate a variable voltage and frequency, the device first converts the communication power of the power source into direct current (DC). This process is called rectification. A device that converts direct current (DC) to communication (AC) is scientifically termed "inverter". A general inverter is an inverter power source that inverts a DC power supply into a fixed fixed frequency and a certain voltage. About inverters are inverters with adjustable frequency and adjustable voltage. We call them inverters. The waveform outputted by the inverter is an analog sine wave. The first is used in the three-phase asynchronous motor speed regulation, also known as the frequency converter. Regarding the variable frequency inverter which is the most demanding waveform used in the instrumentation detection equipment, the waveform must be sorted to output a standard sine wave, called a variable frequency power supply. The general variable frequency power supply is 15-20 times the price of the inverter. Because the primary device of the changed voltage or frequency in the inverter device is called "inverter", the product itself is named "inverter", ie: the inverter.
Frequency conversion is not everywhere to save power, there are many occasions to use frequency conversion and it is not necessary to save power. As an electronic circuit, the inverter itself consumes power (about 3-5% of the extra power). A 1.5-hp air conditioner itself has a power consumption of 20-30W, which is equivalent to a long-light lamp. The inverter operates at the power frequency and has a power-saving function, which is a reality. However, his preconditions are:
First, high power and fan/pump load;
Second, the device itself has power saving function (software support);
This is the three conditions that reflect the power saving effect. Other than that, it doesn't matter if the festival doesn't save electricity. If you do not add preconditions, the inverter power frequency operation is energy-saving, it is exaggerated or commercial speculation. Know the original, you will use him skillfully for you. It is necessary to pay attention to the use of occasions and application conditions in order to use them correctly, or to be obedient and credulous and "deceived."
Power factor compensation energy saving
Reactive power not only increases line loss and equipment heating, but more importantly, the power factor decreases, causing the power loss of the grid to drop, and many reactive energy The cost is on the side of the line, the equipment is inefficient and wasteful. After using the variable frequency speed control equipment, the internal filter capacitor of the inverter reduces the reactive power loss and increases the active power of the power grid.
1: The hard start of the motor has a severe impact on the power grid, and it also requires too much power grid capacity, high current and sensation when starting. The damage of the plates and valves is extremely great, which is extremely unfavorable for the service life of equipment and pipelines. After using the variable frequency energy-saving equipment, the soft-start function of the inverter will make the starting current start from zero, and the large value of zui does not exceed the extra current, which reduces the impact on the power grid and the requirements of the power supply capacity, and prolongs the equipment and valves. Use life. Saves on equipment maintenance costs.
2: In theory, the inverter can be used in all mechanical equipment with electric motor. When the motor is started, the current will be 5-6 times higher than the extra, which will affect the operation of the motor. Life and cost more electricity. The system will have a certain margin in the motor selection during planning, the speed of the motor is fixed, but in the actual application process, sometimes at a lower or higher speed Operation, so it is often necessary to carry out the frequency conversion transformation. The inverter can realize soft start and compensate power of the motor.
Shanghai Kuan Ying Automation Co., Ltd. specializes in the production, sales and sales of industrial automation control products. It is positioned to serve medium and high-end equipment manufacturers and is based on industrial automation control technology with independent intellectual property rights. The customer provides a personalized solution as the main business model to achieve corporate value and customer value grow together.