CN2935576Y

CN2935576Y - Lightning stroke protector for earth-free power source

Info

Publication number: CN2935576Y
Application number: CN 200620106346
Authority: CN
Inventors: 叶林
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-08-03
Filing date: 2006-08-03
Publication date: 2007-08-15
Anticipated expiration: 2016-08-03

Abstract

A non-grounded thunderstroke protector for power supply comprises zinc oxide elements BL1, BL2, BL3, an isolating transformer, a circuit board and a frame, the zinc oxide element BL1 jumping on both ends of the power incoming line. One end of BL2 and BL3 respectively is parallelly connected to two incoming lines of the power supply, and the other end as an entirety is directly connected to the frame. In case of thunderstroke the zinc oxide elements may effectively control over voltage and over potentail brought by thunderstroke, the isolating transformer may effectively remove the thunderstroke residual voltage and isolate the thunder potentail, so as to make sure of safety of the equipments and human lifes when the thunderstroke protector for power supply is not grounded.

Description

Exempt from earthing power supply lightning strike protection device

Technical field

The utility model relates to a kind of power supply lightning strike protection device of earth-free line, is widely used in small-power machine room or small-power electronics electric equipment ground connection difficulty or the higher occasion of ground connection cost.

Background technology

In the prior art, power lightning protection all is the technological means that adopt zinc oxide component in parallel, the direct earth connection of zinc oxide component on electric power incoming line.Most typical lightning protection measures as shown in Figure 1, the lightning surge pulse that forms in low-voltage power supply network is by lightning-arrest element BL ₂, BL ₃With earth connection D and the earth form release by way of, on the approach of releasing, the earth does not absorb the thunderbolt energy to the thunderbolt energy with the whole losses of the form of heat energy, its consumption form can with as Fig. 2 letter show.According to the electrical property of the lightning-arrest element of zinc oxide, the simple physical relational expression of thunderbolt energy A, moment thunderbolt power P, thunderbolt leakage current I, the approach of releasing resistance R:

A＝P·t＝U ²/R＝I ²R

Analyze the characteristic of the output residual voltage of lightning surge pulse after the lightning-arrest element of zinc peroxide suppresses by following formula, available letter is as shown in Figure 3 shown.As shown in Figure 3, the lightning surge pulse shown in Fig. 3 (A), the residual voltage of exporting after the lightning-arrest element effect of zinc oxide among process Fig. 3 (B) is as shown in Fig. 3 (C).U wherein _OThe initial operating voltage (running parameter) of expression zinc oxide component, U _MaxThe maximum functional residual voltage of expression zinc oxide component (is generally 2 times of U _OValue), as can be seen from Figure, output residual voltage amplitude voltage duration T is equal to the energy time T of the pulse of being struck by lightning, and its effect is the amplitude that has suppressed output thunderbolt residual voltage.

According to the lightning-arrest effect of zinc oxide component, we can draw the lightning protection effect of typical shocking preventing technology measure shown in Figure 1, and its effect can be shown with the qualitative letter of Fig. 4.We know that thunderbolt shows that to the harm of electric equipment the thunder and lightning position (shows as U at this _A, U _BValue) and lightning voltage U _ABAt this, we analyze lightning voltage (thunderbolt residual voltage) U earlier _ABThe extent of injury to electric equipment.With regard to the electric equipment of 220V power supply, such security feature: a. is arranged when overvoltage time during less than millisecond, can not damage electric equipment less than 1500 volts overvoltages; B. when overvoltage time during, the power circuit of electric equipment is damaged greater than 280 volts overvoltages greater than millisecond.

To the lightning surge pulse that forms in the mains-supplied electrical network, can be divided into pulse of direct stroke surge and the pulse of indirect lightning strike surge according to the character of being struck by lightning.The direct stroke of this indication be meant lightning discharge and power supply grid (low voltage electric network) contact, and and electrical network form electrical discharge arc, to direct stroke, because the influence of electrical discharge arc, the time of the feasible lightning surge pulse that produces is greater than the time of lightning wave, be the lightning surge pulse that surpasses millisecond, long reaches tens to the hundreds of millisecond; The indirect lightning strike of this indication be meant lightning discharge not and power supply grid (low voltage electric network) contact, do not form electrical discharge arc, to indirect lightning strike, the indirect lightning strike surge burst length is synchronized with lightning wave, duration was generally for tens burst lengths to the hundreds of microsecond less than millisecond.

According to the character of pulse of direct stroke surge and the pulse of indirect lightning strike surge and the characteristic of the lightning-arrest element of zinc oxide, can obtain direct stroke shown in Figure 5 and indirect lightning strike residual voltage U _ABAccording to the characteristics of zinc oxide and heterogeneity of low voltage electric network supply line thunderbolt (balance thunderbolt and uneven thunderbolt) and BL ₂, BL ₃Otherness, be not difficult to find out U _ABIts value:

o＜U _AB＜(U _max-U _O)

The security feature of contrast electric equipment, as can be seen, to indirect lightning strike, because U _ABDuration T＜the 1ms of residual voltage, and amplitude (U _Max-U _O) be controlled in 1500 volts, that is to say output residual voltage U _ABCan not cause damage to electric equipment.To direct stroke, because U _ABDuration T＞the 1ms of residual voltage, and amplitude can not guarantee less than 280 volts, therefore, output residual voltage U _ABElectric equipment is damaged.

In addition, consider U from another possible factor thunder and lightning position that thunderbolt damages _{A (B)}=U _A+ U _C(U _ABe the voltage characteristic of zinc oxide component, U _CBe the ground wire pressure drop) thunder and lightning position U _{A (B)}Act directly on the electric equipment, might make electric equipment cause sparking discharge and counterattack to destroy, thereby electric equipment is damaged.

For this reason, must take equipotential to connect, though connect the safety that can guarantee electric equipment by equipotential, but can cause the earthy raising of equipment, this just might bring the hidden danger of personal life security in the occasion of some man-machine contact, the earth connection that for this reason must do standard is to lower the thunder and lightning position.

Can find out from above-mentioned simple analysis, present stage generally use with national standard in recommend and release type earthing power supply shocking preventing technology and product of formula zinc oxide exist following deficiency: 1, can not fundamentally eliminate the thunderbolt residual voltage; 2, only be that indirect lightning strike is played reliable protection, and can not play reliable protection the electrical network direct stroke; 3, need the support of well behaved standard earth connection, and will take strict equipotential to connect.

For this reason, some producers do some to this lightning protection measures and improve, and serial connection fuse on line design that has or employing concatenation type multi-stage protection adopt damping element to change the characteristic of output residual voltage at inter-stage.Earlier do not consider to change the trouble of fuse at this, single time from fusing is its technical deficiency as can be seen just.Any Fuse Type fuse all has a fusing time, and its fusing time is usually on a few tens of milliseconds.As seen this way can't surpass the residual voltage of millisecond break time, can only surpass the thunderbolt residual voltage of a few tens of milliseconds break time, can not satisfy the requirement of security feature.Because the direct stroke residual voltage is a kind of DC pulse of approximate direct current composition; its tangible this of these damping elements cuts little ice; because the simultaneity of electric transmission; what the final stage of multi-stage protection adopted is the method to set up that parameter diminishes step by step; and this method is owing to be subjected to the lower final stage Influence on security of parameter; final stage often of Sun Huaiing and electric equipment itself at first, this method can not reach the residual requirement less than 280 volts of output.Therefore, these lightning protection measuress are said technically and all can not be guaranteed the safety of electric equipment under electrical network direct stroke situation.

Summary of the invention

The purpose of this utility model is that design at the deficiency of above-mentioned lightning protection measures a kind of exempts from the power lightning protection protector that ground connection, output residual voltage are low, can play reliably protecting to the electrical network direct stroke, have easy to use, advantage such as safety itself can be high, and installation cost is low.

The purpose of this utility model is finished by the following technical programs: thunder resisting equipment is by zinc oxide component BL ₁Be connected across the electric power incoming line two ends, zinc oxide component BL ₂And BL ₃Be attempted by BL after the series connection ₁Two ends, the elementary element BL that is attempted by of isolating transformer B ₁Two ends, the secondary of isolating transformer exported, the contact C ground connection of zinc oxide component BL2 and BL3 perhaps connects the end of zinc oxide component BL4, again by the other end ground connection of BL4 or with the joining isolator of isolating transformer.

Adopt the earthing power supply thunder resisting equipment of exempting from of said structure design to play multiple action, the clamped inhibitory action of lightning surge pulse by BL2 and BL3, embedding fixes in the safe tolerance range of isolating transformer, buffer action by isolating transformer, cut off the DC pulse composition of output residual voltage, thereby guaranteed the safety requirements of the thunderbolt residual voltage of output electric equipment.In addition because the harm approach of thunder and lightning position to electric equipment cut off in the potential isolation effect of isolating transformer.And the personal safety when having guaranteed the thunderbolt of the man-machine contact occasion of protected equipment; because the approach of forming by the good lightning protection earthing line of the system of electrical network own of releasing, make the thunderbolt pulse that produces on the electrical network all cut consumption on this releases approach by this approach and with the form of heat energy.

Description of drawings

Fig. 1 is a comparatively typical power supply lightning strike protection device circuit diagram in the prior art;

Fig. 2 is the mechanism schematic diagram of releasing that is struck by lightning;

Fig. 3 (A) is a thunderbolt pulse energy schematic diagram;

Fig. 3 (B) is the zinc oxide component schematic diagram of releasing;

Fig. 3 (C) is an output residual voltage schematic diagram;

Fig. 4 is the lightning protection effect figure of Fig. 1 lightning protection circuit;

Fig. 5 is the thunderbolt residual voltage U analysis chart of Fig. 1 lightning protection circuit;

Fig. 6 is a kind of circuit theory diagrams of the present utility model;

Fig. 7 is another kind of circuit theory diagrams of the present utility model.

Embodiment

Below by embodiment, and in conjunction with the accompanying drawings, the technical solution of the utility model is described in further detail.

Embodiment 1: referring to Fig. 6; it is by the zinc oxide component BL1 that is connected across the electric power incoming line two ends that the utility model is exempted from ground connection lightning protection power supply; BL2; BL3 forms; the serial connection mid point C of BL2 and BL3 directly meet sb. at the airport shell or with the back that links to each other isolator of isolating transformer T by the BL4 shell of meeting sb. at the airport; if selected BL1; BL2; the operating voltage of BL3 is the zinc oxide component of 800V/1MA; then pass through BL1; BL2; the clamped thunder and lightning position of BL3 compacting can be controlled in the 1500V; the lightning voltage amplitude can be controlled in the 800V; above thunder and lightning position and lightning voltage are in the safe tolerance range of isolating transformer; buffer action by isolating transformer; having cut off the output residual voltage is the direct current fundamental component of 800V; make that the residual voltage surplus after isolating transformer output is very little; be not enough to protected electric equipment is produced security implication; owing to the potential isolation effect of isolating transformer is arranged, has thoroughly cut off the destruction approach of thunder and lightning position.In addition, owing to used good lightning arrester and the lightning protection earthing line of network system, the energy of the lightning surge pulse that produces on the electrical network can be all consumed with the form of heat energy by this approach of releasing, thereby can accomplish to exempt from the security reliability of the electric equipment under the ground connection prerequisite.The utility model is simple in structure, and is easy to use, and the security reliability height is applicable to the safeguard protection of the electric equipment of small-power occasion.

Embodiment 2: referring to Fig. 7, the binding mid point of zinc oxide component BL4 one end and BL2, BL3 links to each other. and the shell of meeting sb. at the airport after the joining isolator of the other end and isolating transformer can prevent the electric leakage safety under the situation that BL2, BL3 damage.All the other reference examples 1.

At last, should be pointed out that above embodiment only is the more representational example of the utility model.Obviously, the utility model is not limited to the foregoing description, and many distortion can also be arranged.Every foundation technical spirit of the present utility model all should be thought to belong to protection range of the present utility model to any simple modification, equivalent variations and modification that above embodiment did.

Claims

1, a kind of earthing power supply lightning strike protection device of exempting from is characterized in that described thunder resisting equipment is by zinc oxide component BL ₁Be connected across the electric power incoming line two ends, zinc oxide component BL ₂And BL ₃Be attempted by BL after the series connection ₁Two ends, the elementary element BL that is attempted by of isolating transformer B ₁Two ends, the secondary of isolating transformer exported, the contact C ground connection of zinc oxide component BL2 and BL3 perhaps connects the end of zinc oxide component BL4, again by the other end ground connection of BL4 or with the joining isolator of isolating transformer.