The active filtering device is a closed indoor device that detects the waveform of the load current in real-time to obtain the harmonic current component that needs to be compensated, and reverses it. By controlling the triggering of the IGBT, the reverse current is injected into the power supply system to achieve the function of filtering (offsetting) harmonics and ensure the safe and effective operation of the power supply system. The active filtering device is required to have advanced technology, mature and reliable production process, and easy installation and maintenance.
The main technical indicators of active filters include:
1. Working voltage: rated voltage 380V ± 15%;
2. Working frequency: 50Hz ± 5%;
3. Device power loss:<3% of rated apparent power;
4. Harmonic frequency control: 2-50 harmonics (selective filtering is possible, and each harmonic compensation can be set separately)
5. Harmonic control rate:>95% (within the rated range);
6. Rated compensation current of a single device: 50A;
7. Switching frequency: 25.6kHz;
8. Reactive power nature: lagging, leading;
9. Response time: ≤ 20ms;
10. Overload capacity: 120% (1min);
11. Noise: ≤ 65dB (1m distance under rated operating conditions);
12. Protection level: IP20 (with anti direct leakage measures);
13. Refrigeration method: forced air cooling;
14. Single box size: 510mm wide box × 595mm deep × 280mm high; Cabinet color: black.
15. Human machine interface: Adopting a 5 or 7-inch backlit LCD display with manually operated button input;
16. Communication protocol: Adopting Modbus remote communication protocol; Communication interface: RS485/RS232
2) Protective measures
1. Fast melting protection
2. Loss of voltage and overvoltage protection (to prevent impact from reclosing incoming calls)
3. Dual protection of voltage, current, hardware, and software
4. Over temperature protection switch
5. Device soft start function
Foreign filter brands include ABB, Schneider, and GE
Choose an active filter. If funds are not tight, it is recommended to choose old foreign brands such as ABB, Schneider, and GE (commonly used in the United States). Siemens (I haven't heard of them having active filters yet). Many of the products launched by these traditional electrical industry leaders share a common feature: mature technology, stability and reliability, and high market demand. If there are too many quality issues with the product and it often breaks down, the consequences are unfavorable for them.
Firstly, the maintenance cost in the later stage is very high. (Their employees have high travel costs, so the best thing for them is to sell the product to you to avoid any worries)
Secondly, it is not good for their brand image (after all, establishing a well-known brand is not easy, and one cannot take a stone and hit oneself in the foot).
Of course, there are other foreign brands, such as Honeywell, Epcos, Nokia, and so on.
In addition, since the introduction of active power filters 10 years ago, there have been some brands in the market under the guise of foreign European and American companies (such as Italy and the United States), which are mixed with good and bad. Some brand names may look grand, but they are actually produced domestically, meeting the mentality of worshiping foreign countries in the domestic market. Therefore, it is necessary to pay attention to discrimination.
If using foreign brands, it is recommended to use pure imported ones. After all, active power filters are electronic products, and the prices of electronic products around the world are similar. Assembly has little impact on their prices, so it is not necessary for foreign investment to invest in production and assembly in China.
Domestic brands: Shenzhen Shenghong, Chongqing Maxwell, Xi'an Cyber, Shanghai Siyuan, and Shanghai Huakun
The quality is unstable, and the price is relatively cheap. The core components of active power filters, such as IGBT, capacitors, CPU, and other domestic electronic components, have unstable technology. Therefore, most domestic manufacturers of APF rely on importing core components from foreign brands and then assembling them domestically. Therefore, the overall cost is not low, mainly due to low labor costs. In addition, the common problem of domestic active power filters is parallel technology, and IGBT parallel technology is not yet qualified. However, the future trend is definitely that after the localization of core devices, the prices of domestic APF manufacturers may truly decrease to a very low level.