1. Dimensions of the inverter control cabinet
2. Scope of application of frequency conversion speed control cabinet
Variable frequency speed control cabinets are used for the control of power equipment in industries such as electric power, metallurgy, coal, building materials and other fields.
3. Characteristics of the frequency conversion speed control cabinet
1. The frequency conversion speed control cabinet adopts high-performance imported frequency conversion speed controller and is equipped with Advanced digital microcomputer control technology, high degree of automation, can realize constant pressure variables, multiple constant pressure variables, variable pressure variables, multiple control methods, multiple start and stop methods, stable pressure, accuracy ≤±1 %;
2, the energy saving effect is significant, the energy saving rate can generally reach 20% ~50%;
3. Microcomputer control realizes frequency conversion soft starting for multiple pumps without inrush current. Mechanical impact wear is small, which can extend the service life of the equipment, improve the stability of the system and reduce the impact on the power grid;
4 Multiple pumps in the equipment can be started cyclically operation, it can balance the workload of each pump and further extend the pump life;
5, the microcomputer controller is powerful, the system design and configuration are flexible, and up to 100% can be set according to needs
5 span>6The control system of the main pump and the 2 small pump attached to the station;
6, suitable for various voltage levels of high and low voltage.
Four, The main performance of the frequency conversion speed control cabinet
1The frequency conversion speed control cabinet has complete fault self-checking and self-processing functions;
2, can self-diagnose overvoltage, undervoltage, overcurrent, overload, phase loss, short circuit, overheating and inverter fault;
3. Send out sound and light signals in time, and can store abnormal status conditions for maintenance and analysis;
4. Fully digital intelligent microcomputer control, which can be controlled according to specific conditions. Modify the operating parameters according to the situation;
5, the frequency conversion speed control cabinet can add various functions according to the needs of users.
a Set up multiple sets of water level control interfaces, which can control several water level signals at the same time and have water cutoff protection function.
bSet the scheduled start and stop program.
c Reserve a remote control interface to realize central monitoring and management of equipment (user optional).
ｄConfigure advanced human-machine interface (user optional).
5. Frequency conversion speed control cabinet selection
P means for daily use, C indicates for air conditioning, X indicates for fire protection, XP indicates for fire sprinkler use, GP means dedicated for industrial high-voltage frequency conversion.
6. Dimensions of the variable frequency speed control cabinet
Outer dimensionsmm (width ⅹ high ⅹ deep) =600ⅹ900ⅹ250 （One for two）
=700ⅹ1800ⅹ400（One drag multiple units）
Note: 15KWThe above cabinets are determined by the power and number of pumps.
7. Key points of inverter cabinet design
1. Heat dissipation problem
The heat of the inverter is generated by internal losses. Among the losses in each part of the frequency converter, the main circuit is the main one, accounting for about 98%, and the control circuit accounts for 2%. In order to ensure the normal and reliable operation of the frequency converter, the frequency converter must be cooled. We usually use fans to dissipate heat; the built-in fan of the frequency converter can take away the heat inside the frequency converter box. If the fan cannot work normally, the frequency converter should be stopped immediately; High-power inverters also need to add fans to the control cabinet. The air ducts of the control cabinet must be reasonably designed, and all air inlets must be equipped with dust screens to ensure smooth exhaust to avoid the formation of eddy currents in the cabinet and dust accumulation in fixed locations; Select a matching fan according to the ventilation volume in the inverter manual. Pay attention to shockproof issues when installing the fan.
2. Electromagnetic interference problem
Due to rectification and frequency conversion during operation, a lot of interfering electromagnetic waves are generated around the inverter. These high-frequency Electromagnetic waves will cause certain interference to nearby instruments and instruments, and will produce high-order harmonics. This high-order harmonics will enter the entire power supply network through the power supply loop, thereby affecting other instruments. If the power of the frequency converter is very large and accounts for more than 25% of the entire system, anti-interference measures for the control power supply need to be considered.
When there are high-frequency impact loads in the system, such as welding machines and electroplating power supplies, the inverter itself will be protected due to interference, and the power quality of the entire system must be considered.
3. The following points need to be noted for protection issues
Waterproof and anti-condensation: If the inverter is placed on site, attention must be paid to the inverter cabinet There must be no pipe flanges or other leaking points, and there must be no splashing water near the frequency converter. In short, the on-site cabinet protection level must be above IP43.
Dust-proof: All air inlets should be equipped with dust-proof nets to block the entry of flocculent debris. The dust-proof nets should be designed to be detachable to facilitate cleaning and maintenance. The grid of the dust-proof net is determined according to the specific conditions of the site, and the connection between the dust-proof net and the control cabinet must be handled tightly.
Protection against corrosive gases: This situation is more common in the chemical industry. At this time, the frequency conversion cabinet can be placed in the control room.
4. Inverter wiring specifications
Signal lines and power lines must be routed separately: when using analog signals to remotely control the inverter ,forTo reduce the interference of analog quantities from frequency converters and other equipment, please separate the signal lines that control the frequency converter from the strong current circuit (main circuit and sequence control circuit). The distance should be more than 30cm. Even in the control cabinet, such wiring specifications must be maintained. The longest control loop line between this signal and the inverter must not exceed 50m.
Signal lines and power lines must be placed inside different metal pipes or metal hoses: if the signal lines connecting PLC and inverter are not placed in metal pipes, it will be extremely dangerous. It is susceptible to interference from the frequency converter and external equipment; at the same time, because the frequency converter does not have a built-in reactor, the input and output stage power lines of the frequency converter will cause strong interference to the outside. Therefore, the metal tube or metal hose where the signal line is placed is always It should be extended to the control terminals of the frequency converter to ensure that the signal lines and power lines are completely separated.
aThe analog control signal line should use a twisted pair shielded wire, and the wire specification is 0.75mm2. Be sure to pay attention when wiring. The cable stripping should be as short as possible (about 5-7mm). At the same time, the shielding layer after stripping should be wrapped with insulating tape to prevent the shielding wire from contacting other equipment and causing interference.
bIn order to improve the simplicity and reliability of wiring, it is recommended to use crimping bar terminals on signal lines.
5. The operation of the frequency converter and the setting of related parameters
The frequency converter has many setting parameters, and each parameter has a certain range of selection. During use, we often encounter the phenomenon that the inverter cannot work properly due to improper settings of individual parameters.
Control method: That is, speed control, torque control, PID control or other methods. After the control method is adopted, static or dynamic identification is generally required based on the control accuracy.
Minimum operating frequency: That is, the minimum speed at which the motor runs. When the motor runs at low speed, its heat dissipation performance is very poor. If the motor runs at low speed for a long time, it will cause The motor is burned out. Moreover, at low speed, the current in the cable will also increase, which will also cause the cable to heat up.
Maximum operating frequency: General frequency converters have a maximum frequency of 60Hz, and some even reach 400 Hz. High frequency will make the motor run at high speed, which For ordinary motors, their bearings cannot operate at over-rated speeds for a long time, and whether the motor’s rotor can withstand such centrifugal force.
Carrier frequency: The higher the carrier frequency is set, the greater the high-order harmonic component will be. This is closely related to the length of the cable, motor heating, cable heating, inverter heating and other factors. related.
Motor parameters:Inverter parametersSet the motor’s power, current, voltage, speed, and maximum frequency. These parameters can be obtained directly from the motor nameplate.
Frequency hopping: At a certain frequency point, resonance may occur, especially when the entire device is relatively high; when controlling the compressor, avoid overshooting of the compressor. surge point.
If the website content violates your rights, please contact us to delete it。
