The varistor is one of the most widely used electronic components. In the application process, the aging of the varistor is its biggest drawback, which will seriously interfere with the normal safety of the system. So, is there any way to effectively suppress the aging problem of varistor? This article will introduce two methods to help engineers effectively solve the aging of varistor.
The first method to be introduced to you is to connect the varistor in parallel with the ceramic discharge tube. This can solve the problem of degradation of the varistor performance after continuous high current, and delay the aging speed. Through the parallel operation with the ceramic discharge tube, the varistor starts to operate before the discharge tube is not turned on, clamping the transient overvoltage, venting the amplified current, and when the discharge tube is discharged, it will be connected with the varistor. The parallel shunting reduces the through-flow pressure to the varistor, thereby shortening the time for the varistor to pass a large current and helping to slow down the performance degradation of the varistor.
In the operation of this parallel combination, there is a problem that engineers need to pay attention to. If the reference voltage Uima of the varistor is selected too low, the discharge tube may not be in the period of transient overvoltage. When the discharge is turned on, the energy of the overvoltage is completely discharged by the varistor, which is unfavorable for the varistor, so the value of Uima must be selected to be larger than the DC discharge voltage of the discharge tube. It must be pointed out that this well combination circuit does not solve the problem of freewheeling that may occur in the discharge tube. Therefore, it is not suitable for the protection of the AC power system.
The second measure to protect the varistor and delay its aging is to connect the varistor in series with the ceramic discharge tube. The circuit diagram in series is shown below:
Series circuit diagram of varistor and ceramic discharge tube
Under normal operating conditions, the varistor often has a large parasitic capacitance in the operation of the circuit system. When it is applied to the protection of the AC power system, it will generate a considerable leakage current under normal operating conditions. For example, a varistor with a parasitic capacitance of 2nF is installed in a 220V, 50hz AC power system with a leakage current of 0.14mA. Such a large leakage current often affects the normal operation of the system. When we connect the varistor in series with the ceramic gas discharge tube, the total capacitance of the entire series branch can be reduced to several microfarads due to the small parasitic capacitance of the discharge tube. In this series combination branch, the discharge tube acts as a switch. When there is no transient overvoltage, it can separate the varistor from the system, so that there is almost no leakage current in the varistor, which can reduce the reference voltage Uima of the varistor without regard to the leakage current. The increase is more effective in slowing down the degradation of the varistor performance.
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Chinese tier 1 brand solar panel
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TIER 1 brand include
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Longi, Jinko, Trina, JA, Canadian, znshine, etc.
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quality warranty
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25 years
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grade
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original A grade (each solar panel can be checked on official website with barcode)
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power range
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400watt to max 700watt
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