Background technology
Lightning protection for power supply (claim lightning arrester or Surge Protector again, be called for short SPD) is made up of several discharge modules, and therefore, the performance of lightning protection for power supply depends on the performance of discharge module basically.
The discharge module of each lightning protection for power supply is main at present is the single Zinc-oxide piezoresistor (MOV) that adopts as shown in Figure 1, also have minority to adopt as shown in Figure 2 MOV and gas discharge tube (GDT) to make up, wherein MOV mostly is SIOV-B32 series of products or the SIOV-B40 series of products that adopt Siemens.GDT has WP company product, Siemens Company's product etc.Its basic functional principle is:
In Fig. 1, when A, B point-to-point transmission voltage U
ABExceed the pressure sensitive voltage U of MOV
1VThe time, piezo-resistance VR
1Conducting, overcurrent I
1VR flows through
1, and with voltage clamp on certain value, protected follow-up equipment.And in Fig. 2, be composed in series discharge module by MOV and GDT, when C, D point-to-point transmission voltage U
CDExceed piezo-resistance VR
2Pressure sensitive voltage U
2VWith GDT G
1Puncture voltage U
1sVR during sum
2With G
1All conductings, overcurrent I
2The discharge module of flowing through on certain value, has been protected follow-up equipment with voltage clamp.The advantage of the discharge module of this structure is simple in structure, is convenient to produce.Its shortcoming is that performance is unexcellent, therefore, some the time marquis also occur lightning protection device when not having thunderbolt from decrease, protected equipment still suffers phenomenons such as thunderbolt damage during thunderbolt.And from the performance index of lightning protection device mainly show following several on;
1), starting resistor U
o: characterize the voltage that lightning protection device begins to discharge, among Fig. 1, U
o=U
1V, among Fig. 2, U
o=U
2V+ U
1sU theoretically
oHigh more good more, lightning protection device can not discharge from decreasing because of power network fluctuation like this.But U
oHigh more, residual voltage is also high more, the protection weak effect.Starting resistor is defined as 2.2 times that are not less than 220V in the relevant criterion of China, i.e. 484V.
2), residual voltage UP: residual voltage is at certain waveform impulse current (this paper indication residual voltage is the thunder and lightning 3KA 8/20 μ s ripple that the GA-173 standard of international standard such as IEC, China etc. is recommended) clamp voltage of lightning protection device (claiming protection voltage again) down; this voltage is that thunder and lightning is through directly being added in the voltage on the follow-up equipment behind the lightning protection device; therefore; residual voltage is the main index of lightning protection device; low more good more; but residual voltage and starting resistor are connected, and promptly residual voltage is low, and starting resistor is also low.Among Fig. 1, by the performance decision of MOV, general residual voltage is about 3 times of starting resistor to residual voltage fully.As U
0=484V, then residual voltage is 1452V.Among Fig. 2, residual voltage is MOV and GDT residual voltage sum, mostly also at 1500V.Therefore, because adopting single MOV or simple MOV and GDT to contact, existing discharge module makes starting resistor U
oWith residual voltage U
PThe parameter of two mutual restriction is difficult to accomplish the starting resistor height and the low such ideal state of residual voltage.Adopt the lightning protection device of traditional discharge module mostly to be now: U
o=500V, U
P=1500V.Cause the overall performance of lightning protection device poor, be difficult to the protection effect that reaches desirable.
Summary of the invention
The purpose of this invention is to provide that a kind of reaction speed is fast, starting resistor is higher and residual voltage is low, long service life and response speed is fast, matching effect is good lightning protection for power supply.
Technical scheme of the present invention is achieved in that a kind of lightning protection for power supply, the wherein discharge module between two lines that is connected to power supply phase line, zero line and ground wire and the performance indicating circuit that comprise at least more than one are formed, wherein discharge module is composed in parallel by main discharge circuit and start-up circuit, and the main discharge circuit is by piezo-resistance VR
2With gas discharge tube G
1Be composed in series, start-up circuit is by piezo-resistance VR
1Form, wherein the gas discharge tube G of main discharge circuit
1Two ends are parallel with resistance R
1, and gas discharge tube G
1Two ends be in series with at least more than one piezo-resistance VR respectively
2, VR
4, be characterized in the resistance R of described main discharge circuit
1Suppress diode T with transition
1After the series connection again with gas discharge tube G
1In parallel.
The present invention is owing to adopt main discharge circuit and start-up circuit structure combining, the start-up circuit that utilization is made up of piezo-resistance solves gas discharge tube and starts the preceding high problem of residual voltage fully, and after gas discharge tube starts fully, bear main discharge by the main discharge circuit, residual voltage of the present invention is remained in the lower scope, and the gas discharge tube of this structure and piezo-resistance can be selected for use to have than the discrete component of low start voltage and realize the overall startup voltage that it is higher, and effectively improve its whole response speed.Simultaneously,, can effectively be reduced in the dividing potential drop at gas discharge tube two ends under the 220V normal condition, guarantee reducing gas discharge tube G in resistance R of gas discharge tube two ends parallel connection
1Under the situation of starting resistor, can not damage gas discharge tube because of the fluctuation of 220V voltage, and by suppressing diode T by resistance R and transition
1Form the electric resistance partial pressure loop, both can suppress diode T1 at gas discharge tube G by transition
1Diode is given a fixing voltage (about about 110V) in advance, thunderstorm hour only need be added again just can start gas discharge tube G after certain voltage (about about 140V) promptly reaches 250V
1, be equivalent to start in advance gas discharge tube G
1, further improve the response speed of main discharge circuit, utilize transition to suppress diode T again
1Nonlinear characteristic, making the electric resistance partial pressure loop also is a nonlinear circuit, thereby be complementary with the nonlinear devices such as piezo-resistance of whole main discharge circuit, guarantee under different piezo-resistance situations, all can select identical resistance R for use, and replace a jumbo piezo-resistance with the less piezo-resistance parallel connection of two or more capacity, can further reduce the residual voltage of main discharge circuit.
Describe basic structure of the present invention and operation principle in detail below in conjunction with accompanying drawing:
Embodiment
Shown in Fig. 3~5, the wherein discharge module between two lines that is connected to power supply phase line, zero line and ground wire and the performance indicating circuit that the present invention includes at least more than one are formed, discharge module is composed in parallel by main discharge circuit and start-up circuit as shown in Figure 5, and wherein the main discharge circuit is by piezo-resistance VR
2With gas discharge tube G
1Be composed in series, start-up circuit is by piezo-resistance VR
1Form.For effectively being reduced in gas discharge tube G under the 220V normal power supply situation
1The dividing potential drop at two ends guarantees reducing gas discharge tube G
1The situation of starting resistor under, can not damage gas discharge tube G because of the fluctuation of 220V
1, as shown in Figure 6, the gas discharge tube G of above-mentioned main discharge circuit in the present embodiment
1Two ends are parallel with resistance R
1, and gas discharge tube G
1Two ends be in series with at least more than one piezo-resistance VR respectively
2, VR
4
Be the further response speed that improves the main discharge circuit, and make resistance R
1Nonlinear device is also arranged in the circuit, and nonlinear devices such as itself and piezo-resistance are complementary, thereby effectively guarantee under the situation of different piezo-resistances, can select identical resistance R for use
1, as shown in Figure 7, the resistance R of above-mentioned main discharge circuit in the present embodiment
1Suppress diode T with transition
1After the series connection again with main body discharge tube G
1In parallel.
For further reducing the residual voltage of main discharge circuit, as shown in Figure 8, above-mentioned piezo-resistance VR in the present embodiment
2, VR
4Two ends be parallel with at least more than one piezo-resistance respectively.In the present embodiment, guaranteeing to reduce under the situation of piezo-resistance starting resistor piezo-resistance VR
2, VR
4Two ends be parallel with a piezo-resistance VR respectively
3Or VR
5
Operation principle of the present invention is: discharge module is made up of main discharge circuit and start-up circuit, wherein the effect of main discharge circuit is the overwhelming majority in the powerful lightning current of releasing, it is to assist the main discharge circuit start that start-up circuit mainly acts on, promptly be before the main discharge circuit is worked fully with the thunder and lightning clamper than low value (being generally about 800V).
When the outside line voltage U
EFWhen exceeding starting resistor of the present invention, the start-up circuit among the present invention starts discharge earlier, main discharge circuit discharging next, and with the residual voltage pincers on certain value.The protection follow-up equipment.
The present invention has made full use of the characteristics of various discharge components and parts and the characteristic of lightning wave, makes its starting resistor higher and residual voltage is lower, and its design feature is as follows:
1), She Ji start-up circuit, make that the reaction speed of whole discharge module is fast: the residual voltage that effectively guarantees whole discharge module is in a lower scope, because of the main discharge circuit has a plurality of MOV device polyphones, make that the response time is the twice of single MOV, and response time and residual voltage are inversely proportional to, therefore, as not adding start-up circuit, then the residual voltage of whole discharge module can be very high.
2), in the main discharge circuit, take two kinds of major measure to make and under the constant situation of starting resistor, reduce residual voltage greatly:
(1), adopt MOV string GDT (GDT also has TVS etc.) to go here and there the MOV structure again, its residual voltage is three part of devices residual voltage sums, the starting resistor of the MOV at two is the same with traditional discharge module with the relation of residual voltage, the key of circuit has sealed in a GDT in the middle of being, the main effect of GDT: the relation that changes starting resistor and residual voltage, GDT has glow discharge and two discharge regimes of arc discharge, and voltage-current characteristic is seen Fig. 9.As seen from Figure 9 the characteristics of GDT be the starting resistor height and after the conducting voltage across poles low, 250V starting resistor product starts the back voltage across poles and is not higher than 30V, that is to say that after the complete conducting of GDT the residual voltage of main discharge circuit is that two MOV residual voltage sums add 30V.The residual voltage of main discharge circuit is very low like this, and starting resistor is three starting resistor sums.But we can find out also that from Fig. 9 such result is after the complete conducting of GDT, but before the complete conducting of GDT (about 100ns of GDT response time) 100ns in the time period, the residual voltage of main discharge circuit still be three part sums be quite high.That is to say that the residual voltage in the main discharge circuit is quite high in 100ns, this problem is solved by start-up circuit.GDT and have TVS (characteristics of TVS be the response time in several ns, but capacity is less) its effect is the response speed that improves the main discharge circuit.MOV combines two big advantages in addition in the main discharge circuit with GDT: utilize the big characteristics of GDT electrode resistance (10
9Level) solves the MOV problem of aging, prolonged the useful life of MOV.Utilize the voltage-current characteristic of MOV to solve the afterflow problem of GDT, protected GDT also to make lightning protection device not influence power supply quality simultaneously.
Below in conjunction with lightning wave the course of work of high starting voltage of the present invention and low residual voltage is described, sees Figure 10, VR1 gets starting resistor 500V, VR in Fig. 6
2To VR
5Get 150V, GDT gets DC250V.TVS gets 180V.
At first, calculate starting resistor, the starting resistor of start-up circuit is VR
1Starting resistor 500V, the starting resistor of main discharge circuit is that the 300V of two groups of MOV adds the about 200V in TVS loop (TVS this as 180V, the resistance 20V that has an appointment) and equals 500V.The starting resistor of two circuit is identical.Secondly, calculate the residual voltage after main discharge starts fully, the residual voltage of two groups of MOV is (150*3) * 2=900V, and the GDT voltage across poles is 30V, and therefore, total residual voltage is 930V.This residual voltage has been compared with the residual voltage of traditional discharge module greatly and has been improved.At last, the GDT that analyzes in the main discharge circuit starts preceding residual voltage fully.Before analysis, to understand the residual voltage Changing Pattern of MOV under impulse current earlier, the residual voltage of MOV is a measured value under certain impulse current, generally get 3KA 8/20 μ s in the world, when impulse current is worth less than this, the residual voltage of MOV just has not been 3 times of starting resistor, smaller, the capacity of occurrence and MOV itself, starting resistor, production technology has very big relation, as: 500V 8KA (the 3KA 8/20 μ s) MOV of actual measurement Siemens is 1510V when the 5KA, and residual voltage is 1450V during 3KA, during 2KA 1350V, being 1000V during 1KA, is 950V during 700A, is 870V during 100A.Can find out that thus residual voltage was 1500V substantially when 3KA was above, the following residual voltage of 700A is just much low.Analyzing the lightning current that GDT starts in the precontract 100ns fully after thunder and lightning reaches the lightning protection device starting resistor below again has much.Among Figure 10,6KV 1.2/50 μ s lightning voltage needs 100ns to reach the A point that starts 500V.Corresponding lightning current just arrives the A1 point of 0.0375KA in 100ns with 3KA 8/20 μ s, GDT also needs 100ns just to start fully from A point (A1 point) beginning, arrived B point (B1 point) this moment, B1 order electric current be 0.075KA, fully can be in 870V according to above-mentioned data start-up circuit with this lightning current clamper.These are the data that obtain under the standard testing ripple, in actual lightning stroke process as big ten times of start-up circuits of lightning current can both be before GDT starts with the thunder and lightning clamper in 900V.
Main discharge circuit also has two characteristics: the one: another effect of the TVS in the main discharge circuit is under normal circumstances the 220V operating voltage to be given GDT two interpolar 110V, thunder and lightning is as long as just begin to have started adding 140V GDT behind the 250V more like this, be equivalent to GDT and start in advance, also accelerated with regard to the response that equals GDT.Secondly: the MOV in the main discharge circuit adopts multi-disc also to connect, and such structure makes that residual voltage ratio adopts the residual voltage of single big capacity MOV low under same starting resistor, and this is that the internal structure of MOV determines.This point can be found from Siemens's product information, as a plurality of S20K150 and connect the back residual voltage be 900V, the residual voltage of single B32K150 is 1100V.Both differ also bigger.
In sum, above-mentioned benefit analysis has been arranged, and the measured result of contrast discharge module of the present invention, the measured result that following table is carried out for the 40KA lightning protection device of the present invention being formed with different impact devices:
Impulse current 8/20 μ s | Residual voltage |
?1KA | ?690V |
?2KA | ?730V |
?3KA | ?830V |
?5KA | ?850V |
?7.5KA | ?880V |
?10KA | ?910V |
?15KA | ?930V |
?20KA | ?950V |
Can reflect clearly that though discharge module structure of the present invention is will be a little than traditional discharge module complicated, function admirable many, specifically relatively see the following form:
Main performance | Module of the present invention | Single MOV module | Explanation |
Starting resistor | 500V | ?500V | Starting resistor is identical, and residual voltage differs greatly |
Residual voltage | 830V | ?1500V |
Leakage current | 3μA | ?12μA | The big MOV that quickens is aging in electric leakage |
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