The interference of higher harmonics on the zero line will seriously affect the operation of the high frequency communication equipment, causing the digital circuit to malfunction, resulting in serious consequences such as communication interruption and system data loss.
It is customary to divide the grid interference into the following categories:
First, low frequency interference.
A. Overvoltage: The voltage continues to be above 10% of the rated value.
B. Long-term pressure: The voltage continues to be less than 15% of the rated value.
C. Power failure: Power supply interruption greater than 300ms.
D. Intermittent: Power interruption is less than 300ms.
E. Surge: The voltage is above 10% of the rated value for a duration of 1 to several cycles.
F. Frequency drift: +2% of the normal value of the frequency offset.
Second, high frequency interference.
A. Spike: A number of letters above the rated voltage, sometimes as high as several thousand volts, with a duration of milliseconds of short-term overvoltage.
B. Glitch: several times higher than the rated voltage, sometimes up to tens of thousands of volts, and the duration is microseconds of instantaneous overvoltage.
C. Higher harmonics: Distortion of the grid waveform due to nonlinearity of the load.
D. The main causes of low frequency interference are:
The opening and closing of large electrical appliances; the grid load changes too much (overload or light load); load short circuit.
The main causes of high frequency interference are:
Non-linear load powered by the grid; radiation generated by equipment operating at high frequencies; lightning; moments of switching of electrical equipment. How to eliminate the impact of various types of interference on the use of electrical equipment, to provide high-reliability, high-quality pure power supply for electrical equipment, the current common practice is:
A. The UPS has a voltage regulation and frequency stabilization function, which eliminates the effects of excessive voltage, low voltage and frequency drift.
B. UPS comes with a battery pack to solve the problem of grid failure and power outage.
C. Harmonic filters are used to effectively filter out higher harmonics.
D. Use radio frequency interference (RFI) filters to eliminate radio frequency interference.
E. Use good shielding measures.
(1) EVADA UPS adopts advanced DSP control technology and double isolated online working mode to make it have excellent voltage stability and anti-interference performance. The input voltage range of IGBT rectifier can be as wide as +25% (normal UPS is +15%) In this range, the output voltage is stable at the rated value. This completely solves the problem of excessive or too low input voltage.
If the input voltage exceeds this range, the battery of the UPS is powered, so that the output voltage remains at the rated value, which solves the problem of grid failure and power failure.
(2) IGBT rectifier power factor correction technology with input harmonic filter and special mid-line design makes the input harmonic distortion less than 10%, power factor is greater than 0.99 (general UPS harmonic distortion is 27% to 34%, The power factor is greater than 0. 9) It not only eliminates the interference of higher harmonics, but also prevents the occurrence of new power grid pollution. It can be called a green UPS. This index is much higher than the grid pollution limit level to be introduced in China (Europe). The current standard is >0.97).
(3) EVADA UPS is equipped with RF interference filter at the input and output terminals. Its electromagnetic compatibility is in accordance with EN50091-2A, which can be used for various broadcasting and communication equipment. The outer casing of the EVADA UPS is made of 2mm thick stainless steel plate and has excellent electromagnetic shielding. It can prevent external interference, ensure the UPS itself to work reliably, and prevent interference to peripheral devices.
In summary, EVADA UPS is especially suitable for all kinds of communication, broadcast and other transmission and reception systems, which can ensure the reliable operation of all kinds of equipment sensitive to grid interference.
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