CN206878452U - Rectifier bridge protection circuit, over-pressure safety device and electric power system - Google Patents

Abstract

The utility model provides a kind of rectifier bridge protection circuit, over-pressure safety device and electric power system, is related to circuit protection technical field, and effective overvoltage protection can be provided for rectifier bridge, so as to extend the service life of rectifier bridge.In the rectifier bridge protection circuit, including full bridge rectifier, over-voltage protector and direct current end protector.Wherein, over-voltage protector is parallel to the both ends of each diode of full bridge rectifier；Direct current end protector includes capacity cell, resistive element and metal oxide lightning rod, and capacity cell is parallel to the DC output end of full bridge rectifier after being connected with metal oxide lightning rod, the resistive element is parallel to the both ends of the capacity cell.

Description

Rectifier bridge protection circuit, over-pressure safety device and electric power system

Technical field

Circuit protection technical field is the utility model is related to, more particularly, to a kind of rectifier bridge protection circuit, overvoltage protection Device and electric power system.

Background technology

At present, in electronic circuit, rectifier bridge is widely used, rectification rectification as important rectifying device Bridge circuit is to be attached by four diodes according to certain mode, forms the electronic device with full-wave rectification function.Hand over Stream electricity is after rectifier circuit rectification, it usually needs LC filter circuits is connect, because the output end of rectifier circuit is connected to LC Filter circuit, in upper electricity or surge moment, moment back-pressure caused by the choke line state in LC filter circuits may exceed rectification The maximum of diode bears voltage in bridge circuit, causes diode over-voltage breakdown, and then causes the damage of whole rectifier bridge, influences Use of the rectifier bridge in Related product.

Therefore, how to realize that carrying out overvoltage protection to rectifier circuit turns into technical problem urgently to be resolved hurrily.

Utility model content

In view of this, the purpose of this utility model be to provide a kind of rectifier bridge protection circuit, over-pressure safety device and Electric power system, rectifier bridge can effectively be protected, extend the service life of rectifier bridge when occurring over-pressed.

In a first aspect, the utility model embodiment provides a kind of rectifier bridge protection circuit, including full bridge rectifier, mistake Press protection device and direct current end protector；

The over-voltage protector is parallel to the both ends of each diode of the full bridge rectifier；

The direct current end protector includes capacity cell, resistive element and metal oxide lightning rod, the capacity cell The DC output end of the full bridge rectifier is parallel to after being connected with the metal oxide lightning rod, the resistive element is simultaneously It is coupled to the both ends of the capacity cell.

With reference in a first aspect, the utility model embodiment provides the first possible embodiment of first aspect, its In, the over-voltage protector includes electric capacity, resistance, Transient Suppression Diode, at least one of discharge tube.

With reference in a first aspect, the utility model embodiment provides second of possible embodiment of first aspect, its In, the rectifier bridge protection circuit also includes overheating protective element, and the overheating protective element accesses the full bridge rectifier Any one of ac input end or DC output end port, the overheating protective element are Thermal Cutoffs or NTC heat Quick resistance.

With reference in a first aspect, the utility model embodiment provides the third possible embodiment of first aspect, its In, the rectifier bridge protection circuit also includes over-current protection device, and the overflow protecting element accesses the full bridge rectifier Any one of ac input end or DC output end port, the over-current protection device are fastp-acting fuse or from remelt Disconnected device.

Second aspect, the utility model embodiment provide a kind of over-pressure safety device, including induction coil, protection chip With the rectifier bridge protection circuit any one of first aspect and its possible embodiment；

The induction coil is used for the secondary iron core for being wrapped in transformer, and produces alternating current impression signal；

The rectifier bridge protection circuit is connected between the induction coil and the protection chip, the rectifier bridge protection The alternating current impression signal rectification is direct current induced signal by circuit；

The protection chip receives the direct current induced signal, described when the direct current induced signal exceeds preset value Protect chip output power-off signal.

With reference to second aspect, the utility model embodiment provides the first possible embodiment of second aspect, its In, the over-pressure safety device also include be connected to the rectifier bridge protection circuit and it is described protection chip between filter circuit and Amplifying circuit.

With reference to second aspect, the utility model embodiment provides second of possible embodiment of second aspect, its In, the protection chip includes comparator and trigger；

The comparator receives the direct current induced signal, and the direct current induced signal is compared with the preset value Compared with；

When the direct current induced signal exceeds preset value, the trigger exports power-off signal.

The third aspect, the utility model embodiment also provide a kind of electric power system, including transformer and second aspect and Over-pressure safety device any one of its possible embodiment；

The primary coil connection power network of the transformer, secondary coil connection ac output end；

Induction coil in the over-pressure safety device is wrapped in the secondary iron core of transformer.

With reference to the third aspect, the utility model embodiment provides the first possible embodiment of the third aspect, its In, the electric power system also includes the first relay, bidirectional triode thyristor and current-limiting resistance；

First output end of the protection chip connects the control line of first relay by the bidirectional triode thyristor Circle；

Second output end of the protection chip connects the control terminal of the bidirectional triode thyristor by current-limiting resistance.

With reference to the third aspect, the utility model embodiment provides second of possible embodiment of the third aspect, its In, the electric power system also includes the second relay；

The output end of first relay is connected with the control coil of second relay, second relay Output end is connected with the primary coil.

The utility model embodiment brings following beneficial effect：

In the rectifier bridge protection circuit that the utility model embodiment provides, including full bridge rectifier, over-voltage protector And direct current end protector.Wherein, over-voltage protector is parallel to the both ends of each diode of full bridge rectifier；DC terminal Protector includes capacity cell, resistive element and metal oxide lightning rod, and capacity cell is connected with metal oxide lightning rod The DC output end of full bridge rectifier is parallel to afterwards, and the resistive element is parallel to the both ends of the capacity cell.This practicality The rectifier bridge protection circuit that new embodiment provides, protected by the overvoltage in parallel of the both ends of each diode in full bridge rectifier Protect device and include capacity cell, resistive element and metal oxide lightning rod in the DC output end setting of full bridge rectifier Direct current end protector, effective overvoltage protection can be provided for rectifier bridge, so as to extend the service life of rectifier bridge.

Other feature and advantage of the present utility model will illustrate in the following description, also, partly from specification In become apparent, or understood by implementing the utility model.The purpose of this utility model and other advantages are illustrating Specifically noted structure is realized and obtained in book, claims and accompanying drawing.

To enable above-mentioned purpose of the present utility model, feature and advantage to become apparent, preferred embodiment cited below particularly, and Accompanying drawing appended by cooperation, is described in detail below.

Brief description of the drawings

, below will be right in order to illustrate more clearly of the utility model embodiment or technical scheme of the prior art The required accompanying drawing used is briefly described in embodiment or description of the prior art, it should be apparent that, describe below In accompanying drawing be some embodiments of the present utility model, for those of ordinary skill in the art, do not paying creativeness On the premise of work, other accompanying drawings can also be obtained according to these accompanying drawings.

Fig. 1 is the schematic diagram for the rectifier bridge protection circuit that the utility model embodiment one provides；

Fig. 2 is the schematic diagram for the over-pressure safety device that the utility model embodiment two provides；

Fig. 3 is the schematic diagram for the over-pressure safety device that the utility model embodiment two provides；

Fig. 4 is the schematic diagram that chip is protected in the over-pressure safety device that the utility model embodiment two provides；

Fig. 5 is the schematic diagram for the electric power system that the utility model embodiment three provides.

Embodiment

To make the purpose, technical scheme and advantage of the utility model embodiment clearer, below in conjunction with accompanying drawing to this The technical scheme of utility model is clearly and completely described, it is clear that described embodiment is that the utility model part is real Apply example, rather than whole embodiments.Based on the embodiment in the utility model, those of ordinary skill in the art are not making The every other embodiment obtained under the premise of creative work, belong to the scope of the utility model protection.

At present, in electronic circuit, rectifier bridge is widely used, rectification rectification as important rectifying device Bridge circuit is to be attached by four diodes according to certain mode, forms the electronic device with full-wave rectification function.Hand over Stream electricity is after rectifier circuit rectification, it usually needs LC filter circuits is connect, because the output end of rectifier circuit is connected to LC Filter circuit, in upper electricity or surge moment, moment back-pressure caused by the choke line state in LC filter circuits may exceed rectification The maximum of diode bears voltage in bridge circuit, causes diode over-voltage breakdown, and then causes the damage of whole rectifier bridge, influences Use of the rectifier bridge in Related product.Based on this, the purpose of this utility model is to provide a kind of rectifier bridge protection circuit, mistake Protection device and electric power system are pressed, rectifier bridge can effectively be protected, extend making for rectifier bridge when occurring over-pressed Use the life-span.

Embodiment one：

The utility model embodiment provides a kind of rectifier bridge protection circuit, as shown in figure 1, the rectifier bridge protection circuit includes Full bridge rectifier, over-voltage protector and direct current end protector.

Wherein, full bridge rectifier is specifically made up of four diodes D1, D2, D3, D4 in a manner of bridge-type connects.Overvoltage Protection device is parallel to the both ends of each diode of full bridge rectifier, and it is (such as general that over-voltage protector includes electric capacity, resistance Be powered resistance, piezo-resistance etc.), Transient Suppression Diode, at least one of discharge tube.Preferably, over-voltage protector includes Electric capacity, or electric capacity formation in series with a resistor RC circuits specifically, the overvoltage protector used in the utility model embodiment Part uses electric capacity, i.e. four electric capacity C11, C12, C13, C14 are connected in parallel on four diodes D1, D2, D3, D4 both ends respectively, directly Stream end protector is connected with positive and negative two output ends of full bridge rectifier, and direct current end protector includes capacity cell C, electricity It is whole that resistance element R and metal oxide lightning rod MOV, capacity cell C are parallel to full-bridge after being connected with metal oxide lightning rod MOV Positive and negative two output ends of direct current of current circuit, resistive element R are parallel to capacity cell C both ends.

Do not possess temperature protection function typically in view of existing rectifier bridge, Antisurge current ability is poor.And typically make The electric current passed through with rectifier bridge is all bigger, and when particularly some big surge currents flow through, rectifier bridge is likely to because electricity Flowing through big or overheat causes inner member to burn, and influences the service life of rectifier bridge.

Further, rectifier bridge protection circuit also includes overheating protective element and/or over-current protection device, overtemperature protection member Any one port of the ac input end or DC output end of part and/or over-current protection device access full bridge rectifier. Wherein, overheating protective element is Thermal Cutoffs or NTC thermistor, and over-current protection device is fastp-acting fuse or runback Fuse.

The factors such as considering cost, environment, it is preferred that overheating protective element is used in the utility model embodiment, is saved About cost while, can play prevent that temperature is too high or electric current it is excessive caused by overheat etc. cause rectifier bridge inner member to damage Bad effect, specifically, overheating protective element uses Thermal Cutoffs FT, Thermal Cutoffs FT to be connected on the D1 of full bridge rectifier On ac input end mouth between D2, Thermal Cutoffs FT is manufactured using bimetal leaf (such as sodium sheet metal), and has There is self-recovering function.When temperature rise reaches predetermined value (fusing point) or has big electric current arrival (over hot melting), bimetallic Piece Thermal Cutoffs produces deformation and disconnecting circuit, when temperature is reduced to certain limit bimetallic temperature fuse can from It is dynamic to return to on-state, it is effectively protected the whole product of rectifier bridge and application rectifier bridge and is unlikely to breakdown damage Phenomenon of the failure.

In the rectifier bridge protection circuit that the utility model embodiment provides, including full bridge rectifier, over-voltage protector And direct current end protector.Wherein, over-voltage protector is parallel to the both ends of each diode of full bridge rectifier；DC terminal Protector includes capacity cell, resistive element and metal oxide lightning rod, and capacity cell is connected with metal oxide lightning rod The DC output end of full bridge rectifier is parallel to afterwards, and the resistive element is parallel to the both ends of the capacity cell.This practicality The rectifier bridge protection circuit that new embodiment provides, protected by the overvoltage in parallel of the both ends of each diode in full bridge rectifier Protect device and include capacity cell, resistive element and metal oxide lightning rod in the DC output end setting of full bridge rectifier Direct current end protector, effective overvoltage protection can be provided for rectifier bridge, so as to extend the service life of rectifier bridge.

Embodiment two：

It is typically using modes such as air switch or relays, to the output line of civil power in view of current overvoltage protector The voltage on road is monitored.It is defeated using the mode such as air switch or relay disconnection, cut-out when the voltage of outlet line is excessive Go out the power supply of circuit, to realize the protection of circuit and electrical equipment.But the sensitivity of existing overvoltage protector is relatively low, Generation can not be protected effectively when over-pressed to circuit.

Based on this, the utility model embodiment also provides a kind of over-pressure safety device, can be applied to family, office, factory Deng power supply scene.As shown in Figures 2 and 3, the over-pressure safety device includes induction coil L1, rectifier bridge protection circuit and protection core Piece.

Wherein, induction coil is used for the secondary iron core for being wrapped in transformer, passes through the magnetic of the primary iron core of sensor transformer Field situation of change, produces alternating current impression signal.Rectifier bridge protection circuit is connected between induction coil L1 and protection chip, is used for The alternating current impression signal rectification that induction coil L1 is sensed is direct current induced signal.Chip is protected to receive direct current induced signal, When direct current induced signal exceeds preset value, protection chip exports power-off signal, disconnects the power supply of transmission line of electricity.

The over-pressure safety device that the utility model embodiment provides, is entered using induction coil L1 to the primary iron core of transformer Row electromagnetic induction, and the condition using induction coil L1 size of current as overvoltage protection, therefore circuit protection can be provided Sensitivity, more efficient protection transmission line of electricity, so as to improve the security of transmission line of electricity.

In the utility model embodiment, by setting rectifier bridge protection circuit, you can realization senses to induction coil L1 Alternating current impression signal carry out rectification, form periodic direct current induced signal.

In the over-pressure safety device that the utility model embodiment provides, in addition to it is connected to rectifier bridge protection circuit and protection Filter circuit between chip.It is filtered in view of most of existing rectifier bridge back using capacitance-resistance, the method is due to electric member Part performance is limited, and resistance, electric capacity volume are larger and expensive, and the filter circuit that the utility model embodiment uses is by one Individual filter capacitor C1 is formed, and cost can also be reduced while realizing filtering and reduces small product size, filter capacitor C1 is in parallel In the output end of rectifier bridge protection circuit, to reduce AC ripple ripple coefficient, smooth direct current output a kind of energy storage device. In using exchange is converted into the electronic circuit of direct current supply, filter capacitor C1 not only makes power supply direct current output steady, reduces Influence of the alternation pulse ripple to electronic circuit, at the same in the also absorbable electronic circuit course of work caused current fluctuation and The interference sealed in via AC power so that the service behaviour of electronic circuit is more stable.It should be noted that filter capacitor C1 The high frequency spurs pollution signal that other electrical appliances are formed in power network can also be filtered out, prevents from causing to do into the overvoltage crowbar Disturb；Second, the high frequency spurs signal for preventing the overvoltage crowbar caused in working enters power network, prevent from making power grid environment Into pollution.

Realized by filter capacitor C1 and direct current induced signal is filtered, the voltage of direct current induced signal is limited in one Within the scope of fixed.

In addition, the output end of filter circuit also protects power end V+, V- of chip by connecting, electricity is provided for protection chip Source.

Further, in the over-pressure safety device that the utility model embodiment provides, in addition to filter circuit is connected to protecting The amplifying circuit protected between chip.Amplifying circuit is mainly made up of the first variable resistor W1 and PNP type triode T1, direct current sensing Signal can generate larger current signal, the current signal is converted to after resistance R3 by triode T1 amplification Induced voltage signal, and input the first input end a1 of protection chip.The voltage-regulator diode D5 to be connected with the first variable resistor W1 With resistance R2, voltage stabilizing and the effect of current limliting are each served as.

In addition, also including the second adjustable resistance W2 in the amplifying circuit, the second adjustable resistance W2, which is used to sense direct current, to be believed Number be converted to reference voltage signal, the second input a2 of input protection chip.

In the present embodiment, variable resistor W1, W2 resistance can be adjusted 0 between 5.1k Ω, variable resistor W1, W2 tool Setting can be adjusted according to the voltage of application scenarios, current conditions when dispatching from the factory in the resistance of body.

Protection chip is mainly monitored to the first input end a1 induced voltage signals received, and according to induced voltage The change output power-off signal of signal.Meanwhile the reference voltage signal for protecting chip to be received to the second input a2 It is monitored, power-off signal can also be exported when reference voltage signal occurs abnormal.

As shown in figure 4, specifically include comparator and trigger in protection chip in the present embodiment.Comparator receives direct current Induced signal (i.e. induced voltage signal and reference voltage signal), and by induced voltage signal and reference voltage signal with it is corresponding Preset value be compared.When induced voltage signal exceeds corresponding preset value, or reference voltage signal beyond corresponding During preset value, trigger will export power-off signal, disconnect the power supply of transmission line of electricity.

As a preferred scheme, trigger is multistable trigger, multistable when direct current induced signal exceeds preset value State trigger exports power-off signal.Multistable trigger is also referred to as n steady state triggers, is the further development of bistable state tentaculum. If having dc-couple between the input of every one-level of n amplifying stage and remaining output end at different levels, can be obtained under certain bar To n stable state, and there was only one-level conducting in each stable state, and remaining is turned off.In nonbinary counter circuit, Quick response under a variety of different conditions can be realized using polymorphic trigger, thus than flip and flop generator response speed more It hurry up.

By using with highly sensitive comparing unit and trigger element in the utility model embodiment, and triggering Multistable trigger is set in unit, protection chip was responded within 0.1 second, is supplied so as to be disconnected within the extremely short time Power supply, effectively protect electrical equipment and supply line.

The over-pressure safety device that the utility model embodiment provides, is entered using induction coil L1 to the primary iron core of transformer Row electromagnetic induction, and the condition using induction coil L1 size of current as overvoltage protection, therefore circuit protection can be provided Sensitivity, more efficient protection transmission line of electricity, so as to improve the security of transmission line of electricity.

Embodiment two：

As shown in figure 5, the utility model embodiment provides a kind of electric power system, including transformer TB and above-described embodiment Two over-pressure safety devices provided.Wherein, transformer TB primary coil L3 connection power networks, secondary coil L2 connections exchange are defeated Go out end, as ac output end, AC power is provided for electrical equipment.Induction coil L1 in over-pressure safety device is wrapped in change The secondary iron core of depressor.

In the electric power system that the utility model embodiment provides, in addition to the first relay J1, bidirectional triode thyristor BG and limit Leakage resistance R4, the output end of chip is protected to connect the first relay J1 control terminal.

Specifically, the protection chip in the present embodiment has two output ends b1, b2.Wherein, the first defeated of chip is protected Go out to hold control coils of the b1 by bidirectional triode thyristor BG the first relays of connection J1；Second output end b2 of protection chip passes through limit Leakage resistance R4 is connected to bidirectional triode thyristor BG control terminal.

Controllable silicon BG is also referred to as IGCT (Silicon Controlled Rectifier, abbreviation SCR), has volume Small, the features such as structure is relatively easy, function is strong, be one of more commonly used semiconductor devices.Controllable silicon BG in the present embodiment For bidirectional thyristor, bidirectional thyristor is a kind of device of bi directional conductibility as bilateral diode, and difference is more one Control section, this just makes it have the working characteristics entirely different with diode.When to the control terminal incoming level of bidirectional thyristor During signal, negative electrode and anode can just turn on.

The level of the second output end b2 outputs of protection chip is transmitted to bidirectional triode thyristor BG control terminal, is made two-way controllable Silicon BG conducting.Meanwhile protect the level that the first output end b1 of chip is exported by bidirectional triode thyristor BG export to first after Electrical equipment J1 control coil, disconnect the first relay J1 output ends, so as to realize the protection of supply line.

In addition, also it is in series with resistance R5 and light-emitting diodes between the second output end b1 and bidirectional triode thyristor BG of protection chip Pipe D6, when protecting chip failure, fault current can make light emitting diode D6 send alarm light, remind user to arrange in time Except failure.

Further, the electric power system that the utility model embodiment provides also includes the second relay J2.First relay J1 Output end connected with the second relay J2 control coil, the second relay J2 output end and transformer TB primary coil L3 connects.

As a preferred scheme, when the first relay J1 is closed type relay, i.e. control coil no power first after Electrical equipment J1 output is in closure state.Meanwhile second relay J2 when being normal-open type relay, i.e. control coil no power First relay J1 output end is off.

In the case of electric power system normal power supply, the first relay J1 control coil no power, the first relay J1 Output in closure state, therefore control power supply to pass through the first relay J1 and supplied to the second relay J2 control coil Electricity.Second relay J2 control coil is in the case of energization, and its output is in closure state, to maintain transformer TB's Primary coil L3 continued powers.Meanwhile the first output end b1 and the second output end b2 of chip is protected to be exported without level signal.

When protecting the trigger element in chip to send power-off signal, the first relay J1 control coil is powered, and makes the One relay J1 output end disconnects.Because the first relay J1 output end disconnects, therefore the second relay J2 control line Circle power-off, disconnects the second relay J2 output end, so as to cut off the connection of power network and transformer TB primary coil L3, with The power supply of electric power system is cut off, realizes the protection of supply line.

In the present embodiment, the first relay J1 uses closed type relay, and the second relay J2 uses normal-open type relay Have further the advantage that：, can be the first relay J1 output end and the second relay J2's in the electric power system of reality The relay for multiple different purposes of being connected between control coil, such as relay for arc protection, the relay of overvoltage protection Device, and the relay for short-circuit protection.These relays also all use closed type relay, and each relay is defeated Go out control coil of the end all with the second relay J2 connect, then wherein the disconnection of any one relay when, can make second after Electrical equipment J2 control coil power-off, so as to cut off the power supply of power system.

The over-pressure safety device and electric power system that the utility model embodiment provides, provided with above-described embodiment one whole Bridge protection circuit is flowed, there is identical technical characteristic, so can also solve identical technical problem, reaches identical technology effect Fruit.

In addition, in the description of the utility model embodiment, unless otherwise clearly defined and limited, term " installation ", " connected ", " connection " should be interpreted broadly, for example, it may be being fixedly connected or being detachably connected, or integratedly be connected Connect；Can be mechanical connection or electrical connection；Can be joined directly together, can also be indirectly connected by intermediary, can To be the connection of two element internals.For the ordinary skill in the art, above-mentioned term can be understood with concrete condition Concrete meaning in the utility model.

, it is necessary to explanation in description of the present utility model, term " " center ", " on ", " under ", it is "left", "right", " perpendicular Directly ", the orientation of the instruction such as " level ", " interior ", " outer " or position relationship are based on orientation shown in the drawings or position relationship, are only Described for the ease of description the utility model and simplifying, rather than instruction or imply signified device or element must have it is specific Orientation, with specific azimuth configuration and operation, therefore it is not intended that to limitation of the present utility model.

In addition, term " first ", " second ", " the 3rd " are only used for describing purpose, and it is not intended that instruction or implying phase To importance.

Finally it should be noted that：Embodiment described above, only specific embodiment of the present utility model, to illustrate this The technical scheme of utility model, rather than its limitations, the scope of protection of the utility model is not limited thereto, although with reference to foregoing The utility model is described in detail embodiment, it will be understood by those within the art that：It is any to be familiar with this skill For the technical staff in art field in the technical scope that the utility model discloses, it still can be to the skill described in previous embodiment Art scheme is modified or can readily occurred in change, or carries out equivalent substitution to which part technical characteristic；And these modifications, Change is replaced, and the essence of appropriate technical solution is departed from the spirit and model of the utility model embodiment technical scheme Enclose, should all cover within the scope of protection of the utility model.Therefore, the scope of protection of the utility model described should be wanted with right The protection domain asked is defined.

Claims (10)

1. a kind of rectifier bridge protection circuit, it is characterised in that protected including full bridge rectifier, over-voltage protector and DC terminal Protect device；

The over-voltage protector is parallel to the both ends of each diode of the full bridge rectifier；

The direct current end protector includes capacity cell, resistive element and metal oxide lightning rod, the capacity cell and institute The DC output end that the full bridge rectifier is parallel to after metal oxide lightning rod is connected is stated, the resistive element is parallel to The both ends of the capacity cell.

2. rectifier bridge protection circuit according to claim 1, it is characterised in that the over-voltage protector include electric capacity, Resistance, Transient Suppression Diode, at least one of discharge tube.

3. rectifier bridge protection circuit according to claim 1, it is characterised in that also including overheating protective element, the mistake Thermal protective element accesses the ac input end of the full bridge rectifier or any one port of DC output end, the mistake Thermal protective element is Thermal Cutoffs or NTC thermistor.

4. rectifier bridge protection circuit according to claim 1, it is characterised in that also including over-current protection device, the mistake Flow protection element and access the ac input end of the full bridge rectifier or any one port of DC output end, the mistake It is fastp-acting fuse or self-mending fuse to flow protection device.

5. a kind of over-pressure safety device, it is characterised in that including induction coil, protection chip and such as any one of claim 1-4 Described rectifier bridge protection circuit；

The induction coil is used for the secondary iron core for being wrapped in transformer, and produces alternating current impression signal；

The rectifier bridge protection circuit is connected between the induction coil and the protection chip, the rectifier bridge protection circuit It is direct current induced signal by the alternating current impression signal rectification；

The protection chip receives the direct current induced signal, when the direct current induced signal exceeds preset value, the protection Chip exports power-off signal.

6. over-pressure safety device according to claim 5, it is characterised in that also include being connected to the rectifier bridge protection electricity Filter circuit and amplifying circuit between road and the protection chip.

7. over-pressure safety device according to claim 5, it is characterised in that the protection chip includes comparator and touched Send out device；

The comparator receives the direct current induced signal, and by the direct current induced signal compared with the preset value；

When the direct current induced signal exceeds preset value, the trigger exports power-off signal.

A kind of 8. electric power system, it is characterised in that the overvoltage guarantor including transformer and as described in any one of claim 5 to 7 Protection unit；

The primary coil connection power network of the transformer, secondary coil connection ac output end；

Induction coil in the over-pressure safety device is wrapped in the secondary iron core of the transformer.

9. electric power system according to claim 8, it is characterised in that also including the first relay, bidirectional triode thyristor and limit Leakage resistance；

First output end of the protection chip connects the control coil of first relay by the bidirectional triode thyristor；

Second output end of the protection chip connects the control terminal of the bidirectional triode thyristor by current-limiting resistance.

10. electric power system according to claim 9, it is characterised in that also including the second relay；

The output end of first relay is connected with the control coil of second relay, the output of second relay Connected with the primary coil at end.