A comprehensive analysis of the principles of various lightning protection circuits
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AC power lightning protection62)] (I) Single-phase parallel lightning arrester Circuit 1: The simplest circuit [attach] 407319 [/attach] Description: 1. Advantages: The circuit is simple, using a composite symmetrical circuit, full common mode and differential mode protection, L and N can be connected at will. Disadvantages: The short circuit failure of the varistor RV1 is prone to cause a fire. It is best to connect a power frequency fuse in series with each varistor to prevent the varistor from short-circuiting and catching fire. If the L and N lines cannot be connected reversely, the varistors RV2 and RV3 can be omitted, and the upper end of the discharge tube G can be directly connected to the N line to form a "1+1" circuit. 2. Refer to the table below to select the varistor voltage value (a higher varistor voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher); select the size and packaging form according to the current capacity requirements, or use several varistors in parallel (parallel connections with similar varistor voltages should be selected to extend the service life and ensure safety). 3. The current capacity of the ceramic gas discharge tube is selected according to the required current capacity, and the DC breakdown voltage is 470V~600V. When the required current capacity is ≤3KA, a glass discharge tube can be used instead. 4. The current capacity of both the varistor and the gas discharge tube must be calculated according to the derating value of more than 10 impacts (the varistor is about one-third of the current capacity of a single impact, and the gas discharge tube is about half of the maximum current capacity). Circuit 2: Safer Circuit [attach] 407321 [/attach] Description: 1. Advantages: It adopts composite symmetrical circuit, common mode and differential mode full protection, L and N can be connected at will, there is no leakage current during normal operation, and the service life of the device can be extended. Since the failure mode of ceramic gas discharge tube is mostly open circuit, it is not easy to cause fire. Disadvantages: In case the varistor and the ceramic gas discharge tube both fail in short circuit, there may be a fire. 2. The varistor voltage value is selected according to the table below (a higher varistor voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher); select the size and packaging form according to the current capacity requirements, or use several varistors in parallel (parallel connections with similar varistor voltages should be selected to extend the service life and ensure safety). 3. The current capacity of the ceramic gas discharge tube is selected according to the required current capacity, and the DC breakdown voltage is 470V~600V. When the required current capacity is ≤3KA, a glass discharge tube can be used instead. 4. The current capacity of both the varistor and the gas discharge tube must be calculated according to the derating value of more than 10 impacts (the varistor is about one-third of the current capacity of one impact, and the gas discharge tube is about half of the maximum current capacity). Circuit 3: General safety protection circuit Description: 1. Advantages: It adopts a composite symmetrical circuit, with full common mode and differential mode protection. L and N can be connected at will, which is safe. The varistor can be disconnected from the circuit after a short circuit failure, and generally will not cause a fire. 2. Refer to the table below to select the varistor voltage value (a higher varistor voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher); select the size and packaging form according to the current capacity requirements, or use several varistors in parallel (parallel connections with similar varistor voltages should be selected, and each varistor should be connected in series with a temperature fuse to extend the service life and ensure safety). 3. The temperature fuse is generally 130℃～135℃, 10A/250V, and should have good thermal coupling with the varistor. It is best to connect a power frequency fuse in series to prevent the power frequency overvoltage from instantly breaking down the varistor and catching fire. 4. The current capacity of the ceramic gas discharge tube is selected according to the required current capacity, and the DC breakdown voltage is 470V～600V. When the required current capacity is ≤3KA, a glass discharge tube can be used instead. 5. The current capacity of both the varistor and the gas discharge tube must be calculated according to the derating value of more than 10 impacts (the varistor is about one-third of the current capacity of one impact, and the gas discharge tube is about half of the maximum current capacity). (II) Three-phase parallel lightning arrester Circuit 1: The simplest circuit [attach] 407325 [/attach] Description: 1. Advantages: The "3+1" circuit is adopted, the circuit is simple, and the three-phase full protection. Disadvantages: The varistor is prone to fire after short circuit failure. It is best to connect a power frequency fuse in series with each varistor to prevent the varistor from short circuiting and catching fire. 2. Refer to the table below to select the varistor voltage value (a higher varistor voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher); select the size and packaging form according to the current capacity requirements, or use several varistors in parallel (as shown in the figure, two varistors are connected in parallel for each phase, and the varistor voltage values should be selected in parallel to extend the service life and ensure safety). 3. The current capacity of the ceramic gas discharge tube is selected according to the required current capacity, and the DC breakdown voltage is 470V~600V. When the required current capacity is ≤3KA, a glass discharge tube can be used instead. 4. The current capacity of both the varistor and the gas discharge tube must be calculated according to the derating value of more than 10 impacts (the varistor is about one-third of the current capacity of a single impact, and the gas discharge tube is about half of the maximum current capacity). Circuit 2: Safer Circuit [attach]407327 [/attach] Description: 1. Advantages: Adopting "3+1" circuit, full protection of three phases, no leakage current during normal operation, can extend the service life of the device, and since the failure mode of ceramic gas discharge tube is mostly open circuit, it is not easy to cause fire. Disadvantages: In case both the varistor and the ceramic gas discharge tube fail in short circuit, it may cause fire. 2. The varistor voltage value of the varistor is selected according to the table below (a higher varistor voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher); select the external dimensions and packaging form according to the current capacity requirements, or use several varistors in parallel (as shown in the figure, two varistors are connected in parallel for each phase, and varistors with similar voltage values should be selected in parallel to extend the service life and ensure safety). 3. The current capacity of the ceramic gas discharge tube is selected according to the required current capacity, and the DC breakdown voltage is 470V~600V. When the required current capacity is ≤3KAWhen the current capacity of the varistor and the gas discharge tube must be calculated according to the derating value of more than 10 impacts (the current capacity of the varistor is about one-third of the current capacity of one impact, and the current capacity of the gas discharge tube is about half of the maximum current capacity). Circuit 3: General safety protection circuit 407329 Description: 1. Advantages: "3+1" circuit is adopted, which has full three-phase protection and is safe. The varistor can be disconnected from the circuit after short circuit failure, and generally will not cause fire. 2. Refer to the table below to select the varistor voltage value (a higher varistor voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher); select the size and packaging form according to the current capacity requirements, or use several varistors in parallel (as shown in the figure, two varistors are connected in parallel for each phase. The varistor voltage value should be similar. Each varistor should be connected in series with a temperature fuse to extend the service life and ensure safety). 3. The temperature fuse is generally 130℃～135℃, 10A/250V, and should have good thermal coupling with the varistor. It is best to connect a power frequency fuse in series to prevent the power frequency overvoltage from instantly penetrating the varistor and catching fire. 4. The current capacity of the ceramic gas discharge tube is selected according to the required current capacity, and the DC breakdown voltage is 470V～600V. When the required current capacity is ≤3KA, a glass discharge tube can be used instead. 5. The current capacity of both the varistor and the gas discharge tube must be calculated according to the derating value of more than 10 impacts (the varistor is about one-third of the current capacity of a single impact, and the gas discharge tube is about half of the maximum current capacity). (III) Single-phase series lightning arrester Single-phase general safety protection circuit: [attach]407331 [/attach] Description: 1. Advantages: It adopts a two-stage composite symmetrical circuit, full common mode and differential mode protection, low residual pressure, L and N can be connected at will, safe, the varistor can be disconnected from the circuit after short circuit failure, and generally will not cause fire. 2. Refer to the table below to select the varistor voltage value (a higher varistor voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher); select the size and packaging form according to the current capacity requirements, or use several varistors in parallel (as shown in the figure, the first stage is m varistors in parallel, and the second stage is n varistors in parallel. The parallel connection with similar varistor voltages should be selected, and each varistor should be connected in series with a temperature fuse to extend the service life and ensure safety). 3. The temperature fuse is generally 130℃～135℃, 10A/250V, and should have good thermal coupling with the varistor. It is best to connect a power frequency fuse in series to prevent the power frequency overvoltage from instantly breaking down the varistor and catching fire. 4. The current capacity of the ceramic gas discharge tube is selected according to the required current capacity, and the DC breakdown voltage is 470V~600V. When the required current capacity is ≤3KA, a glass discharge tube can be used instead. 5. The current capacity of both the varistor and the discharge tube must be calculated according to the derating value of more than 10 impacts (the varistor is about one-third of the current capacity of one impact, and the discharge tube is about half of the maximum current capacity). 6. The series inductor is a hollow inductor, the inductance should be ≥20μH, and the wire diameter should be calculated according to the load current. (IV) Three-phase series lightning arrester Three-phase universal safety protection circuit: [attach] 407333 [/attach] Description: 1. Advantages: Adopting two-stage "3+1" circuit, three-phase full protection, low residual voltage, safe, the varistor can be disconnected from the circuit after short circuit failure, generally will not cause fire. 2. The varistor voltage value is selected according to the table below (a varistor with a higher voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher); select the external dimensions and packaging form according to the current capacity requirements, or use several varistors in parallel (as shown in the figure, the first stage is m varistors in parallel, and the second stage is n varistors in parallel. The varistor voltage should be selected in parallel. Each varistor should be connected in series with a temperature fuse to extend the service life and ensure safety). 3. The temperature fuse is generally 130℃～135℃, 10A/250V, and should have good thermal coupling with the varistor. It is best to connect a power frequency fuse in series to prevent the power frequency overvoltage from instantly breaking down the varistor and catching fire. 4. The current capacity of the ceramic gas discharge tube is selected according to the required current capacity, and the DC breakdown voltage is 470V～600V. When the required current capacity is ≤3KA, a glass discharge tube can be used instead. 5. The current capacity of both the varistor and the discharge tube must be calculated according to the derating value of more than 10 impacts (the varistor is about one-third of the current capacity of a single impact, and the discharge tube is about half of the maximum current capacity). 6. The series inductor is a hollow inductor, the inductance should be ≥20μH, and the wire diameter should be calculated according to the load current.51)] (I) Parallel DC power supply lightning arrester 1. Positive grounded (-48V) DC power supply [attach] 407335 [/attach] Description: 1. Select the varistor from the models marked on the figure (the one with a higher varistor voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher); select the outer size and packaging form according to the current capacity requirements, or use several varistors in parallel (parallel connections with similar varistor voltages should be selected, and each varistor should be connected in series with a temperature fuse to extend the service life and ensure safety). 2. The temperature fuse is generally 130℃～135℃, 10A/250V, and should have good thermal coupling with the varistor. It is best to connect a current fuse in series to prevent the varistor from catching fire due to instantaneous breakdown of the operating overvoltage. 3. The current capacity of the ceramic gas discharge tube is selected according to the required current capacity, and the DC breakdown voltage is generally 90V. When the required current capacity is ≤3KA, a glass discharge tube can be used instead. 4. The current capacity of both the varistor and the gas discharge tube must be calculated according to the derating value of more than 10 impacts (the varistor is about one-third of the current capacity of a single impact, and the gas discharge tube is about half of the maximum current capacity). 2. Negative ground (+24V) DC power supply 407336 Description: 1. Select the varistor from the models marked on the figure (the one with higher varistor voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher); select the outer size and packaging form according to the current capacity requirements, or use several varistors in parallel (parallel connections with similar varistor voltages should be selected, and each varistor should be connected in series with a temperature fuse to extend the service life and ensure safety). 2. The temperature fuse is generally 130℃～135℃, 10A/250V, and should have good thermal coupling with the varistor. It is best to connect a current fuse in series to prevent the varistor from catching fire due to instantaneous breakdown of the operating overvoltage. 3. The current capacity of the ceramic gas discharge tube is selected according to the required current capacity, and the DC breakdown voltage is generally 90V. When the required current capacity is ≤3KA, a glass discharge tube can be used instead. 4. The current capacity of both the varistor and the gas discharge tube must be calculated according to the derating value of more than 10 impacts (the varistor is about one-third of the current capacity of a single impact, and the gas discharge tube is about half of the maximum current capacity). 3. Positive and negative symmetrical DC power supply 407337 Description: 1. Select the varistor from the models marked on the figure (the one with higher varistor voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher). Select the size and packaging form according to the current capacity requirements, or use several varistors in parallel (parallel connections with similar varistor voltages should be selected, and each varistor should be connected in series with a temperature fuse to extend the service life and ensure safety). 2. The temperature fuse is generally 130℃～135℃, 10A/250V, and should have good thermal coupling with the varistor. It is best to connect a current fuse in series to prevent the varistor from catching fire due to instantaneous breakdown of the varistor by the operating overvoltage. 3. The current carrying capacity of the ceramic gas discharge tube is selected according to the required current carrying capacity, and the DC breakdown voltage is generally 150V. When the required current carrying capacity is ≤3KA, a glass discharge tube can be used instead. 4. The current carrying capacity of both the varistor and the gas discharge tube must be calculated according to the derating value of more than 10 impacts (the varistor is about one-third of the current carrying capacity of a single impact, and the gas discharge tube is about half of the maximum current carrying capacity) (II) Series DC power supply lightning arrester 1. Positive grounded (-48V) DC power supply 407338 Description: 1. Select the varistor from the models marked on the figure (the varistor with a higher voltage is safer, more durable, and has a lower failure rate, but the residual pressure is slightly higher). Select the size and packaging form according to the current carrying capacity requirements. The required current carrying capacity is Im When the voltage is large, the first and second stages can be connected in parallel with m and n varistors respectively as shown in the figure (parallel connections with similar varistor voltages should be selected, and each varistor should be connected in series with a temperature fuse to extend its service life and ensure safety), and the first stage Im1≥Im, the second stage Im2≥(0.2～0.3)Im is estimated. 2. The temperature fuse is generally 130℃～135℃, 10A/250V, and should have good thermal coupling with the varistor. It is best to connect a current fuse in series to prevent the operating overvoltage from instantly breaking down the varistor and catching fire. 3. The current capacity of the first ceramic gas discharge tube G1 is selected according to the required current capacity Im, and the second discharge tube G2 can be selected with reference to the second stage Im2. 4. The current carrying capacity of both the varistor and the discharge tube must be calculated according to the derating value after more than 10 impacts (the current carrying capacity of the varistor is about one-third of the current carrying capacity of a single impact, and the current carrying capacity of the discharge tube is about half of the maximum current carrying capacity). 5. The series inductor is a hollow inductor, the inductance should be ≥20μH, and the wire diameter should be calculated according to the load current. 2. Negative ground (+24V) DC power supply 407339 Description: 1. Select the varistor from the models marked on the figure (the varistor with higher voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher). Select the outer size and packaging form according to the current capacity requirements. When the current capacity Im is required to be large, the first and second stages can be connected in parallel with m and n varistors respectively as shown in the figure (parallel connections with similar varistor voltages should be selected, and each varistor must be connected in series with a temperature fuse to extend its service life and ensure safety). According to the first stage Im1≥Im, the second stage Im2≥(0.2～0.3) Im estimation. 2. The temperature fuse is generally 130℃～135℃, 10A/250V, and should have good thermal coupling with the varistor. It is best to connect a current fuse in series to prevent the instantaneous breakdown of the varistor and fire caused by the operating overvoltage. 3. The current capacity of the first ceramic gas discharge tube G1 is selected according to the required current capacity Im, and the second discharge tube G2 can be selected according to the second-level Im2. 4. The current capacity of both the varistor and the discharge tube must be calculated according to the derating value of more than 10 impacts (the varistor is about one-third of the current capacity of a single impact, and the discharge tube is about half of the maximum current capacity). 5. The series inductor is a hollow inductor, the inductance should be ≥20μH, and the wire diameter should be calculated according to the load current. 3. Positive and negative symmetrical DC power supply Description: 1. Select the varistor from the models marked on the figure (the one with a higher varistor voltage is safer, more durable, and has a lower failure rate, but the residual voltage is slightly higher). Select the external dimensions and packaging form according to the current capacity requirements. When the current capacity Im is required to be large, the first and second levels can be connected in parallel with m and n varistors respectively as shown in the figure (parallel connections with similar varistor voltages should be selected, and each varistor should be connected in series with a temperature fuse to extend the service life and ensure safety). It is estimated according to the first level Im1≥Im and the second level Im2≥（0.2～0.3）Im. 2. The temperature fuse is generally 130℃～135℃, 10A/250V, and should have good thermal coupling with the varistor. It is best to connect a current fuse in series to prevent the varistor from catching fire due to instantaneous breakdown of the operating overvoltage. 3. The current capacity of the ceramic gas discharge tube should be selected according to the required current capacity. 4. The current capacity of both the varistor and the gas discharge tube must be calculated according to the derating value of more than 10 impacts (the varistor is about one-third of the current capacity of a single impact, and the gas discharge tube is about half of the maximum current capacity). 5. The series inductor is a hollow inductor, the inductance should be ≥20μH, and the wire diameter should be calculated according to the load current. General two-stage signal lightning arrester (I) Twisted pair type General circuit 1: 407340 Description: ① R1 and R2 can be ordinary metal oxide film resistors (2W-4.3~5.1Ω), or positive temperature coefficient thermistors with equivalent cold resistance (such as: resettable fuse: LP60-010/030, LB180 (U)). ②The DC breakdown voltage of ceramic gas discharge tube and TVS tube is selected according to the signal voltage amplitude, see the table below: 407341 General circuit 2: 407342 Note: ①R1 and R2 can be ordinary metal oxide film resistors (2W-4.3～5.1Ω), or positive temperature coefficient thermistors with equivalent cold resistance (such as: resettable fuse: LP60-010/030, LB180 (U)). ②The DC breakdown voltage of the glass discharge tube and TVS tube is selected according to the signal voltage amplitude, see the table below: 407343 ③This circuit is only suitable for occasions where the impulse current is not greater than the maximum pulse discharge current of the glass discharge tube, and there is no continuous DC voltage in the circuit. General circuit three: 407344 Explanation: ①R1 and R2 can use ordinary metal oxide film resistors (2W-4.3～5.6Ω), or positive temperature coefficient thermistors with equivalent cold resistance (such as: self-resettable fuse: LP60-010/030, LB180 (U)). ②The DC breakdown voltage of ceramic gas discharge tube and semiconductor overvoltage protector is selected according to the signal voltage amplitude, see the table below: 407345 ③This circuit is only applicable to the occasion where there is no continuous DC voltage in the circuit. General circuit 4: 407346 Note: ①R1 and R2 can use ordinary metal oxide film resistors (2W-4.3～5.6Ω), or positive temperature coefficient thermistors with equivalent cold resistance (such as: self-resettable fuse: LP60-010/030, LB180 (U)). ②The DC breakdown voltage of ceramic gas discharge tube and semiconductor overvoltage protector is selected according to the signal voltage amplitude, see the following table: 407347 ③When using a low-voltage semiconductor overvoltage protector, the glass discharge tube must be connected in series at the ground end as shown in the figure; when using a semiconductor overvoltage protector with a voltage higher than 100V, the glass discharge tube can be omitted. ④This circuit is only suitable for occasions where there is no continuous DC voltage in the circuit. General circuit 5: 407348 Description: ① R1 and R2 can use ordinary metal oxide film resistors (2W-4.3～5.1Ω), or positive temperature coefficient thermistors with equivalent cold resistance (such as: self-resettable fuse: LP60-010/030, LB180 (U)). ② The DC breakdown voltage of ceramic gas discharge tube and TVS tube is selected according to the signal voltage amplitude, see the following table: 407349 ③ This circuit is suitable for transmitting high-frequency/high-speed signals (the highest frequency can reach 20MHZ). (II) Coaxial Line Type (1) Outer Conductor Grounding Circuit: General Circuit 1: 407350 Description: ① R1 and R2 can be made of ordinary metal oxide film resistors (2W-4.3～5.1Ω), or a positive temperature coefficient thermistor with equivalent cold resistance (such as: self-resettable fuse: LP60-010/030, LB180 (U)). ②The DC breakdown voltage of the ceramic gas discharge tube and TVS tube is selected according to the signal voltage amplitude, see the following table: ③The circuit bandwidth is very wide and can transmit high-frequency signals below 20MHZ. ④The input and output connectors should match the connector types of the original system respectively. General circuit 2: [attach] 407352 [/attach] Description: ① R1, R2 can be ordinary metal oxide film resistors (2W-4.3 ~ 5.6Ω), or positive temperature coefficient thermistors with equivalent cold resistance (self-resettable fuses: LP60-010/030, LB180 (U)). ② The DC breakdown voltage of ceramic gas discharge tubes and semiconductor overvoltage protectors is selected according to the signal voltage amplitude, see the following table: [attach] 407353 [/attach] ③ This circuit is only suitable for occasions where there is no continuous DC voltage in the circuit. ④ The input and output connectors should match the connector types of the original system respectively. General circuit three: Description: ①This circuit is only suitable for occasions where the signal frequency/rate is low and there is no continuous DC voltage in the circuit. ②R can use ordinary metal oxide film resistors (2W-4.3～5.6Ω) or positive temperature coefficient thermistors with equivalent cold resistance (self-resettable fuses: LP60-010/030, LB180 (U)). ③The DC breakdown voltage of the glass discharge tube and semiconductor overvoltage protector is selected according to the signal voltage amplitude, see the following table: ④The input and output connectors should match the connector types of the original system respectively. (2) Circuit with ungrounded outer conductor: General circuit 1: 407356 Description: ① The circuit bandwidth is very wide and can transmit high-frequency signals below 20MHZ. ② The DC breakdown voltage of the ceramic gas discharge tube and TVS1 is selected according to the signal voltage amplitude, see the following table: 407357 ③ R1 and R2 can use ordinary metal oxide film resistors (2W-4.3～5.1Ω), or positive temperature coefficient thermistors with equivalent cold resistance (such as self-resetting fuses: LP60-010/030, LB180 (U)). ④ The input and output connectors should match the connector types of the original system. General circuit 2: [attach] 407358 [/attach] Description: ① R1, R2 can be ordinary metal oxide film resistors (2W-4.3 ~ 5.1Ω), or positive temperature coefficient thermistors with equivalent cold resistance (such as: self-resettable fuse: LP60-010/030, LB180 (U)). ② The DC breakdown voltage of the glass discharge tube and semiconductor overvoltage protector is selected according to the signal voltage amplitude, see the following table: [attach] 407359 [/attach] ③ This circuit is only suitable for occasions with low signal frequency/rate. ④ The input and output connectors should match the connector type of the original system respectively. (III) Methods to improve transmission frequency/rate 1. Use low capacitance TVS tube or semiconductor overvoltage protector. Transmission frequency/rate ≥10MHz, Cj≤60pF; Transmission frequency/rate ≥100MHz, Cj≤20pF. 2. Connect the TVS tube or semiconductor overvoltage protector in series into the high-speed rectifier bridge (as shown in the figure below): 407360 Small power transformer or switching power supply protection circuit Circuit 1: 407361 Description: ① The self-recovery fuse PTC is selected according to the input current and the maximum operating ambient temperature. The current-carrying capacity of the varistor RV1 is selected according to the input surge current (if one is not enough, several can be connected in parallel, refer to "I. AC power lightning arrester"). The varistor voltage should be selected between 470 and 620V (a higher voltage should be selected where the voltage is very unstable). ② RV2 and RV3 select the varistor voltage value according to the values of U1 and U2, and the size is selected according to the length of the output line. When there is no long lead, use 5D or 7D. When using long lead output, a varistor with larger current capacity should be selected (the longer the lead, the larger the current capacity). ③ Ceramic gas discharge tubes generally use a DC breakdown voltage of 470V, and the current capacity is selected according to the input surge current. Circuit 2: 407361 Description: ① The self-resetting fuse PTC is selected according to the input current and the maximum operating environment temperature. The current carrying capacity of the varistor RV1 is selected according to the input surge current (if one is not enough, several can be connected in parallel, refer to "I. AC power lightning arrester"), and the varistor voltage should be selected between 470 and 620V (a higher voltage should be selected where the voltage is very unstable). ② TVS1 and TVS2 generally use 1.5KE series (P6KE series can also be used where the surge current is very small), and the breakdown voltage value (VBRmin≥1.2Up). ③ Ceramic gas discharge tubes generally use a DC breakdown voltage of 470V, and the current capacity is selected according to the input surge current. ④ This circuit is only suitable for use in places where the output end does not have a long lead and the surge current is small (for example, on the same circuit board or adjacent circuit boards). Circuit 3: [attach]407362 [/attach] Description: ① The self-resettable fuse PTC is selected according to the input current and the maximum operating ambient temperature, and the current capacity of the varistor RV1 is selected according to the input surge current (if one is not enough, several can be used in parallel, refer to "I. AC power supply lightning arrester"), and the varistor voltage should be selected between 470 and 620V (a higher voltage should be selected in places where the voltage is very unstable). ② RV2 and RV3 select the varistor voltage value according to the values of U1 and U2, and the size is selected according to the length of the output line. When there is no long lead, use 5D or 7D. When using long lead output, a varistor with larger current capacity should be selected (the longer the lead, the larger the current capacity). When the output current is large, the self-recovery fuse PTC2 and PTC3 should be connected in series on the line (select according to the output current and the maximum ambient temperature). ③ Ceramic gas discharge tubes generally use a DC breakdown voltage of 470V, and the current capacity is selected according to the input surge current. Protection circuit of communication electronic equipment Circuit 1: 407363 Description: ① This circuit is suitable for overhead line introduction or other occasions with large surge current. ② The maximum discharge current of the ceramic gas discharge tube is generally 10kA or 5kA, and the DC breakdown voltage is selected according to the signal voltage amplitude, see the following table: ③ TVS tube uses P6KE220CA type. If there is no ringing signal on the transmission line, P6KE68CA type can be used. ④ R1 and R2 can use ordinary metal oxide film resistors (4.3～5.6Ω), or positive temperature coefficient thermistors with equivalent cold resistance (such as: self-resettable fuse: LP60-010/030, LB180 (U)). Circuit 2: 407365 Description: ①Used in the introduction of buried cables or other occasions with small surge current. ②BLSA1 and BLSA2 use YA-301 or YS-301 glass discharge tubes. ③TVS tubes use P6KE220CA. If there is no ringing signal on the transmission line, TVS tubes can use P6KE68CA. ④R1 and R2 can use ordinary metal oxide film resistors (3.6～5.1Ω), or positive temperature coefficient thermistors with equivalent cold resistance (such as: self-resettable fuses: LP60-010/030, LB180 (U)). Circuit 3: [attach] 407366 [/attach] [attach] 407367 [/attach] Description: ① Used in the introduction of buried cables or other occasions with small surge current. ② R1 and R2 can use ordinary metal oxide film resistors (3.6 ~ 5.1Ω), or positive temperature coefficient thermistors with equivalent cold resistance (such as: self-resettable fuse: LP60-010/030, LB180 (U)). ③ When using a semiconductor overvoltage protector with a low voltage (≤100V), a glass discharge tube (BLSA3) must be connected in series at the ground end as shown in the figure; when using a semiconductor overvoltage protector with a voltage higher than 100V, the glass discharge tube can be omitted. DC power supply and signal transmission 1. 110V ungrounded power supply and signal transmission: Circuit 1 407368 Circuit 2 407369 2. +24V negative grounded power supply and signal transmission: Circuit 1 407370 Circuit 2 407371 Secondary dual protection method of signal circuit 407372 Description: The component models marked in the figure are suitable for signal amplitude ≤6V. The P0080 connected in the rectifier bridge can be replaced by a P6KE7.5A TVS tube (negative end facing left). For other signal amplitudes, the component models must be replaced. Protection of detection/control circuits For example: water, electricity, gas meter reading systems, access control, intercom, and alarm systems. These systems generally use low-frequency (pulse) signals or DC (AC) switching signals. These systems are divided into two categories: ungrounded systems and grounded systems. (1) Ungrounded system protection circuit: [attach]407373 [/attach] Description: ①R1 and R2 can be ordinary metal oxide film resistors (4.3~5.1Ω), or a positive temperature coefficient thermistor with equivalent cold resistance (such as: resettable fuse: LP60-010/030, LB180 (U)). ② The DC breakdown voltage of ceramic gas discharge tube and TVS tube is selected according to the signal voltage amplitude, see the following table: ③ When there is no continuous DC voltage in the circuit, the TVS tube can be replaced by a semiconductor overvoltage protector with equivalent breakdown voltage. When the surge current is small, the ceramic gas discharge tube can be replaced by a glass discharge tube with equivalent breakdown voltage. (2) Grounding system protection circuit: 407375 Note: ①R can be a common metal oxide film resistor (4.3~5.1Ω), or a positive temperature coefficient thermistor with equivalent cold resistance (such as: self-resettable fuse: LP60-010/030, LB180 (U)). ②The DC breakdown voltage of ceramic gas discharge tube and TVS tube is selected according to the signal voltage amplitude, see the following table: 407376 ③When there is no continuous DC voltage in the circuit, the TVS tube can be replaced by a semiconductor overvoltage protector with equivalent breakdown voltage. When the surge current is small, the ceramic gas discharge tube can be replaced by a glass discharge tube with equivalent breakdown voltage. Single-stage signal lightning arrester 1. Protection circuit using only glass discharge tube Description: ①It can be used in situations where the signal frequency/transmission rate is very high but there is no continuous DC voltage. ②The DC breakdown voltage of the glass discharge tube should be selected according to the peak value of the signal voltage as follows: VBRmin≥1.2USpeak ③It can protect ungrounded two-wire transmission lines, and can also independently protect the lines that need to be protected in a transmission system with a common grounding line (as shown by the dotted line in the figure). 2. Protection circuit using only semiconductor overvoltage protector 407378 Description: ① It can be used in situations where the signal frequency/transmission rate is low and there is no continuous DC voltage. ② The breakdown voltage of the semiconductor overvoltage protector should be selected according to the signal peak voltage as follows: VBR≥1.2USpeak ③ When the breakdown voltage of the semiconductor overvoltage protector is lower than 100V, a two-terminal semiconductor overvoltage protector or glass discharge tube with a breakdown voltage greater than 100V should be connected in series at the ground end and then grounded, as shown in the figure below. ④ When there is a common ground line in the transmission line (as shown by the dotted line in the figure), the circuit of "(1) without differential mode protection" can be used to protect line 1, line 2, etc. separately. 3. Protection circuit using only TVS tube 407380 Description: ① It can be used in situations where the signal frequency/transmission rate is low, there may be continuous DC voltage in the line, and the surge current is small. ②The DC breakdown voltage of the TVS tube should be selected according to the peak value of the signal voltage as follows: VBRmin≥1.2USpeak③When the grounding line is long and the signal is susceptible to interference, a TVS tube or glass discharge tube with a breakdown voltage greater than 100V can be connected between TVS1 and TVS2 (left figure) or TVS2 and TVS3 (right figure) and then grounded, as shown in the figure below. ④When there is a common grounding line in the transmission line (as shown by the dotted line in the figure), the circuit of "(1) without differential mode protection" can be used to protect line 1, line 2, etc. respectively. 4. Composite protection circuit [attach] 407382 [/attach] Description: ① It can be used in situations where the signal frequency/transmission rate is high (≤10MHZ). If the rectifier bridge is composed of fast recovery diodes, the transmission signal frequency/rate can reach more than 20MHz. ② When there is continuous DC voltage in the line, circuit 2 must be used. ③ The component models marked in the figure are suitable for signal amplitudes ≤6V. When the signal amplitude is larger, the component models connected in the rectifier bridge should be replaced (refer to the description of the selection of TVS tubes and semiconductor overvoltage protectors in the "two-stage signal protection circuit"). ④ When the ground wire is long and the signal is easily interfered, TVS1 and TVS2 should use TVS tubes with a breakdown voltage ≥100V and a larger peak pulse power, or use circuit 3. Antenna lightning arrester51)]1. Single-stage circuit antenna feed lightning arrester [attach]407383 [/attach] Description: ① It can transmit power at the same time, but the protection effect is poor. It is suitable for occasions where the antenna does not have an amplifier or has an amplifier but has strong impact resistance. ② The coaxial cavity and the connectors at both ends are specially designed and processed according to the connector type used in the system and the frequency range of the transmitted signal. ③ Ceramic gas discharge tubes are generally selected with a current capacity of 20kA. The DC breakdown voltage is mainly selected according to the power of the transmitted signal. Generally, 90V is used for less than 50W. The greater the transmission power, the higher the DC breakdown voltage should be. ④ After the discharge tube is installed in the cavity, the standing wave coefficient and insertion loss within the signal frequency range tested by a microwave network analyzer should meet the requirements. ⑤When used outdoors, the cavity, connectors, and discharge tube mounting holes must be designed to be waterproof. 2. Secondary Circuit Antenna Feeder Lightning Arrester 407384 Description: ①Good protection effect, low residual pressure, can transmit power at the same time, suitable for occasions where the antenna is with or without an amplifier. ②The cavity and input and output connectors are specially designed and processed according to the connector type used in the system and the frequency range of the transmitted signal. ③Ceramic gas discharge tubes are generally selected with a current capacity of 20kA and a DC breakdown voltage of 90V. ④TVS tubes are generally 1.5KE series, and the breakdown voltage is selected according to the transmitted DC voltage or AC voltage peak (VBRmin≥1.2UDC or VBRmin≥1.2Up). ⑤ C is a plate capacitor made of copper sheets, with polytetrafluoroethylene film added between the plates; L1 and L3 are hollow inductors wound with enameled copper wire, and L2 can use an iron core inductor of about 100μH. ⑥ After the components are installed in the cavity, the standing wave coefficient and insertion loss within the signal frequency range tested by a microwave network analyzer should meet the requirements. ⑦ When used outdoors, the cavity, connectors and cover must be designed to be waterproof. 3. Three-level circuit antenna feed lightning arrester Description: ① The protection effect is very good, the residual pressure is low, and the power supply can be transmitted at the same time. It is suitable for occasions where the antenna is equipped with an amplifier or without an amplifier. ② The cavity and the input and output connectors are specially designed and processed according to the connector type used in the system and the transmission signal frequency range. ③Ceramic gas discharge tubes are generally selected with a current capacity of 20kA and a DC breakdown voltage of 90V. ④Varistor RV is generally selected as 20D100K type. ⑤TVS tubes are generally 1.5KE series, and the breakdown voltage is selected according to the DC voltage or AC voltage peak value transmitted (VBRmin≥1.2UDC or VBRmin≥1.2Up). ⑥C is a flat plate capacitor composed of copper sheets, with polytetrafluoroethylene film added between the plates; L1 and L4 are hollow inductors wound with enameled copper wire, and L2 and L3 can use iron core inductors of about 100μH. ⑦After the components are installed in the cavity, the standing wave coefficient and insertion loss within the signal frequency range tested by a microwave network analyzer should meet the requirements. ⑧When used outdoors, the cavity, joints and cover must be designed to be waterproof. Anti-static protector 407385 Description: ① "Circuit 1" has the shortest response time and a small flow rate, and is suitable for equipment, components or circuits that cannot be grounded; ② "Circuit 2" has a short response time, and the flow rate can be large or small, and is suitable for equipment, components or circuits that cannot be grounded; ③ "Circuit 3" has a very short response time and a large flow rate, and is suitable for equipment, components or circuits that can be grounded; ④ "Circuit 4" has a short response time and a small flow rate, and is suitable for equipment, components or circuits that can be grounded; ⑤ The breakdown voltage (varistor voltage) of the device used should be lower than the highest voltage that the protected equipment, components or circuit can withstand, but higher than the highest working voltage of the circuit. The flow rate is selected according to the current value converted from the maximum electrostatic charge that may be induced. Source: Internet. If copyright is involved, please contact us to delete. 2Up). ⑥C is a flat plate capacitor made of copper sheets, with polytetrafluoroethylene film between the plates; L1 and L4 are hollow inductors wound with enameled copper wire, and L2 and L3 can use iron core inductors of about 100μH. ⑦After the components are installed in the cavity, the standing wave coefficient and insertion loss within the signal frequency range tested by a microwave network analyzer should meet the requirements. ⑧When used outdoors, the cavity, connectors and cover must be designed to be waterproof. Anti-static protector 407385 Description: ① "Circuit 1" has the shortest response time and a small flow rate, and is suitable for equipment, components or circuits that cannot be grounded; ② "Circuit 2" has a short response time, and the flow rate can be large or small, and is suitable for equipment, components or circuits that cannot be grounded; ③ "Circuit 3" has a very short response time and a large flow rate, and is suitable for equipment, components or circuits that can be grounded; ④ "Circuit 4" has a short response time and a small flow rate, and is suitable for equipment, components or circuits that can be grounded; ⑤ The breakdown voltage (varistor voltage) of the device used should be lower than the highest voltage that the protected equipment, components or circuit can withstand, but higher than the highest working voltage of the circuit. The flow rate is selected according to the current value converted from the maximum electrostatic charge that may be induced. Source: Internet. If copyright is involved, please contact us to delete. 2Up). ⑥C is a flat plate capacitor made of copper sheets, with polytetrafluoroethylene film between the plates; L1 and L4 are hollow inductors wound with enameled copper wire, and L2 and L3 can use iron core inductors of about 100μH. ⑦After the components are installed in the cavity, the standing wave coefficient and insertion loss within the signal frequency range tested by a microwave network analyzer should meet the requirements. ⑧When used outdoors, the cavity, connectors and cover must be designed to be waterproof. Anti-static protector 407385 Description: ① "Circuit 1" has the shortest response time and a small flow rate, and is suitable for equipment, components or circuits that cannot be grounded; ② "Circuit 2" has a short response time, and the flow rate can be large or small, and is suitable for equipment, components or circuits that cannot be grounded; ③ "Circuit 3" has a very short response time and a large flow rate, and is suitable for equipment, components or circuits that can be grounded; ④ "Circuit 4" has a short response time and a small flow rate, and is suitable for equipment, components or circuits that can be grounded; ⑤ The breakdown voltage (varistor voltage) of the device used should be lower than the highest voltage that the protected equipment, components or circuit can withstand, but higher than the highest working voltage of the circuit. The flow rate is selected according to the current value converted from the maximum electrostatic charge that may be induced. Source: Internet. If copyright is involved, please contact us to delete.
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