Schneider inverter manufacturers: how to choose the right inverter capacity
Schneider Inverter Manufacturer: How to choose the right inverter capacity, the choice of inverter capacity is An important and messy problem, we must consider the matching between the inverter capacity and the motor capacity. The small capacity will affect the output of the effective torque of the motor, affect the normal operation of the system, and even damage the equipment. If the capacity is too large, the harmonic component of the current will Increased, also increased equipment funding.
1. Matching criteria
(1) Power matching: The extra power of the inverter is consistent with the extra power of the load; it should be noted that the power requirements of the motor are different. For example, for motors of the same power, the capacity of the inverter required for different load characteristics is also different. The inverter capacity required for the square torque load (fan) is lower than the inverter capacity required for the constant torque load. Generally, the inverter product specification directly gives the extra power suitable for driving the motor or its apparent power. Therefore, for the square torque load such as the fan and the pump, the corresponding inverter can be selected according to the motor power.
(2) Voltage matching: The extra voltage of the inverter matches the extra voltage of the load.
(3) Current matching: general centrifugal pump, the additional current of the inverter is selected to match the extra current of the motor; special load, for example, deep water pump, need to consider the motor performance parameters, determine the inverter current with large current And overload.
(4) Torque matching: Consider when using constant torque load or when there is a gear reduction device.
2, economic criteria
Technical analysis and economic analysis should be carried out, and the control plan with satisfactory performance requirements and high performance-price ratio should be selected.
3. Specific analysis criteria for specific conditions
The different usage conditions should be analyzed and the inverter capacity determined.
(1) Select the motor capacity according to the inverter product manual: In the following conditions, the inverter capacity can be selected according to the inverter product specification.
(2) When selecting the inverter capacity, the demand should be selected according to the capacity of the manual. The first or second gear is selected: the following conditions require the first gear or the second gear.
(3) When the inverter is selected as the inverter capacity target to select the inverter, since the influence of the motor pole number and the motor extra current is not considered, the inverter is selected according to the additional power of the inverter. , perhaps the selected frequency converter is not satisfied with the motor extra current requirements.
(4) When the motor is used as the inverter capacity, the inverter is selected. Because the motor capacity is not considered, there is usually a certain margin, especially for the inverter modification project. The margin is generally 40% to 50%. Therefore, when the inverter capacity is selected according to the additional current of the motor, the inverter may have an excessive margin, which causes the inverter to operate under low load, causing resource dross.
In addition, the large running current of the motor zui affects the heating and temperature rise of the motor. For short-time overload, the inverter usually has an overload of 150% and 1 min. Therefore, for applications where the load is shaken, When selecting the inverter, you should know the large running current and overload time of the motor, so that the inverter will not exceed its extra current when the turbine is running at a large current, or the overload current is less than 150% extra current when the overload time is less than 1min.
(5) The proper matching of the inverter and the motor means that the additional current of the motor (or the large operating current of zui) should be less than the additional current of the inverter of the same power. For example, from the table, the original 8-pole 18.5kW motor is selected from the same power inverter. Because of the large load shake, ABB's ACS800 series products are selected.
(6) When the inverter capacity is reduced, pay attention to the motor starting current and accelerating the impact of current. For this reason, it is considered to add an output reactor between the inverter and the motor to filter and smooth the inrush current and accelerate the current, reduce the inrush current, and accelerate the impact of the current; it will accelerate under the premise of satisfying the acceleration and deceleration of the production process. The setting of the deceleration time is longer; the preset value of U/f is set smaller when starting.
