Use the equation for table type

P = T × N / 975 P-the power of the motor T-motor torque N-the motor speed To constant torque, system design should note:
(1) motor elected inverter special motor
(2) the frequency conversion ark should be special cooling fan
(3) increase motor capacity, reduce the load characteristics
(4) increase the capacity of the frequency converter
(5) of the frequency converter capacity and the capacity of the motor should be based on the relationship between the brand, generally in
1.1 ~ 1.5 the capacity of the motor.
2. Square torque load. If the fan, of pump Use the equation table type for T = K1 × N2, P = K2 × N3 P-motor power T-motor torque N-the motor speed Generally, the fan, water pump, variable frequency energy-saving, theoretical and actual proof for 40 ~ 50% of energy savings, such application of frequency converter application 30 to 40%. To square torque load, system design should note:
(1) motor usually chooses synchronized motors. According to rotating joints the environment needs, choose motor protection grade and the way.
(2) be more than 7.5 KW frequencies arks should add ventilation cooling facilities
(3) motor, frequency converter capacity relationship. 3. Constant power load. Such as hoists, spindle. Formula: P = T N / 975 = CONT. General of specific speed section, the constant torque, more than specific speed, the constant power operation. Constant power Mechanical properties are more complex. For each frequency conversion control cabinet design is that the entire system key, can manifest the product quality a key link. For frequency conversion control cabinet, electrical design engineers should design in the following aspects.
1. The frequency conversion controls system of the principal diagrams design
2. Running circuit design.
3. Circuit controls road design. Includes regular control circuit, PLC control interface circuit, frequency converter networking, etc.
4. Frequency conversion controls cabinet process design. Include electrical technology design, cabinet put oneself in another's position sheet metal process design. Principle diagram design According to the above principle rules, with reference to the principle of variable frequency control cabinet figure, according to actual needs, draw the principle diagram. Running circuit design. According to the following sequence of main loop electric parts of choice.
(1) determining the mechanical load characteristics, power, torque and speed
(2) sure motor characteristics, rated voltage, power rating, rated current,
(3) according to rotary union the above conditions, and actual customer need, to the following the electrical components a choice TR-transformer is optional, according to standard voltage level, matching. FU-fusing silk, typically, the choice of 2.5-4 times rated current frequency converter. Pay attention to fuse choice of melting speed wire. QA-empty open, typically, the choice of 1.2 times the rated current frequency converter KM-contactor, must want to, the choice for rated current frequency converter LY-lightning protection surge implements, had better be, especially a thunderstorm pilosity area, and the ac power spikes surge multiple occasions, protect frequency conversion system from accidental damage. General to 40 KVA surge devices. DK-reactor The role of the reactor is inhibiting the input output current heavy high harmonic the ill effects of ingredients, and the role of the filter is inhibited brought by the frequency converter radio waves interference, namely waves noise. Some inverter built-in reactor, some occasions also can pack reactor. In general, the more high-power inverter with much reactor, frequency converter manufacturers to provide parameters. Choose the parameters of the reactor, the formula below L =  2% ~ 5%  V / 6.18 by F × I V-the rated voltage V I-A rated F-the biggest frequency HZ LBI/LBO input/output filter, generally should be based on frequent configuration R-braking resistance calculation is more complex. Frequency converter should be under the guidance of the art manufacturer configuration. Circuit controls circuit design, press electrical engineer knowledge and frequency converter design requirements. But they should pay attention to
(1) input/output weak electric signal, and PLC, instrument, sensing transmitter, must take signal isolating, otherwise, the control system signal chaos, the system doesn't normal.
(2) and PLC, conventional control system interface, must add surge absorber.
(3) control of the power supply should use the isolated transformer, electrical isolation. Frequency conversion controls cabinet process design.
(1) electric process design Electrical engineer frequency circuit design out, the next step is to electrical technology design, including:
1. Much high-power inverter, match what type cable, how big the line diameter, match for. General can check form or calculation.
2. Grounding the wiring.
3. Anti-interference wiring. Is very important. General in high voltage cables uses tape screened cable, cable and shielding layer metallic card with fixed base plate, and some of the shielding metal ring, anti-jamming.
4. The outlet pipe connector cable configuration. Cabinet put oneself in another's position sheet metal process design According to fiber optic rotary joint the following principles should be designed
1. A frequency converter on the environment Temperature: Inverter environment temperature-10 degrees-50 degrees, must consider to ventilation cooling. Humidity: Vibrations: Gas: whether blast, corrosive gas
2. Load weight cabinet put oneself in another's position.
3. Transportation convenience. The lifting hook, handling safety.
4. The nameplate Cabinet put oneself in another's position of manufacturer, CI logo. A high quality of frequency conversion control cabinet, from design, process, production manufacture, transportation, packaging, and is the actual demand higher product, the requirements of quality guarantee each link, to make higher quality and level of control cabinets.