CN108879673A - A kind of low-voltage safety power supply system - Google Patents
A kind of low-voltage safety power supply system Download PDFInfo
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- CN108879673A CN108879673A CN201810843103.2A CN201810843103A CN108879673A CN 108879673 A CN108879673 A CN 108879673A CN 201810843103 A CN201810843103 A CN 201810843103A CN 108879673 A CN108879673 A CN 108879673A
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B9/00—Power cables
- H01B9/006—Constructional features relating to the conductors
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Abstract
The present invention relates to a kind of low-voltage safety power supply systems, including step-down transformer, power transmission line, earth leakage circuit-breaker and electrical equipment, wherein：Equipped with isolating transformer; the armature winding of the isolating transformer connects the output of the step-down transformer; the secondary windings of the isolating transformer connects electrical equipment by earth leakage circuit-breaker; secondary windings neutral point, that is, zero curve of the isolating transformer is earth-free; the power transmission line is the clad type power transmission line with conductive coating, and the conductive coating of the clad type power transmission line is electrically connected the secondary windings neutral point of the isolating transformer.Common ground is not accessed by the neutral conductor of isolating transformer secondary, the current loop to have broken between the earth from power supply unit lateral incision, it can be avoided the circuit in electric appliance or equipment or part electric leakage, leakage current can not pass through human body, the earth is connected, to effectively prevent the generation for leading to human body casualty accident because of electric shock.
Description
Technical field
The present invention relates to power supply system technical fields, and in particular to a kind of low-voltage safety power supply system.
Background technique
Power supply system is by producing electricl energy of forming of power-supply system and electrical power trans mission/distribution system and supplies and be conveyed to electrical equipment
System.Existing power supply system is divided into three classes, i.e. TN system, TT system and IT system.
In TN system, the exposed conductive part of all electrical equipments is connected on protective wire, and the ground connection with power supply
Point is connected, this grounding point is usually the central point of distribution system, also known as zero line protection.When failure makes electrical equipment metal shell
When electrification, phase line and earth short are formed, loop resistance is small, and electric current is big, can enable protective device action message, failure is cut
It removes.
TT system is the three-phase four wire system that mains neutral point is directly grounded, and the exposed conductive part of all devices passes through
Respective protective wire PE is directly grounded respectively.
IT system refers to that the exposed conductive part of all devices is through respective in mains neutral point earth-free system
Protective wire PE is directly grounded respectively.IT mode power supply system is when power supply distance is not very long, the high reliablity of power supply, safety
It is good.Since mains neutral point is earth-free, once equipment leakage, single-phase Ground leakage current is still small, will not destroy the flat of supply voltage
Weighing apparatus, so also safer than the system of mains neutral point ground connection.
TN system and IT system are generally three-phase three-wire system power supply, due to not having zero curve, are not suitable for needing single-phase
The occasion of power supply.Therefore, the three-phase and four-line TT that general city factory and residential electricity consumption mostly use mains neutral point to be directly grounded is supplied
Electric system.
Existing three-phase and four-line TT power supply system is as shown in Figure 1, including supply transformer 1, power transmission line 2, earth leakage circuit-breaker
3, electrical equipment 4,5.Wherein electrical equipment 4 is three phase electric equipment, and 5 be single-phase electric devices；Transformer 1 is three phase-change pressures
Device, input termination high-voltage fence, the 3 phase high-voltage electricity that high-voltage fence is sent are depressured into the input voltage phase with electrical equipment
Match, line voltage is lower than the three-phase four-wire power supply voltage of 1000V, and phase voltage is line voltageIt is three-phase in China
380V and single-phase 220V.The power transmission line 2 is usually using single insulated conductor or 3 phase insulated cables or single-phase insulated cable
Or the 3 phase insulated cables with zero curve.In TT power supply system, neutral point, that is, zero line grounding of transformer output end, and require
6 reliable ground of external conductive casing of electrical equipment.
Existing system presses IEC standard, and the middle line (zero curve) of the 4 line power supply system of three-phase is grounded, in electrical equipment
Route damage can constitute circuit by shell with shell short circuit, and keep sheath voltage is zero over the ground, not will cause touching to people
Touch the casualty accident of personnel.Earth leakage circuit-breaker is further refilled, (human body is born once leakage current is more than 25 to 30 milliamperes
Safe current value), i.e., can cut off power supply.
But the casualty accident for thering are personnel to electrocute when in fact still, it was demonstrated that existing system is not perfect enough, still has and changes
Kind space.The size of TN, TT system firewire earth leakage current is unable to control, if leakage switch fails, personnel once contact fire
Line is in peril of one's life.IT system mains neutral point is earth-free, and no-voltage, touching will not electricity over the ground for the external conductive casing of electric leakage equipment
People, but the electric leakage between Line To Line can not be prevented, and whether shell charge can not detection.
There are two kinds of Danger Electric shock risks generally in service area：
1, line gets an electric shock over the ground
In power supply system of the existing voltage higher than 36V, when people's will outer contacting phase line (live line) or electric leakage shell, people will
It is placed between uneasy full voltage and common ground, only ensures person peace by the leakage switch worked normally and good ground connection
Entirely.Often due to the ground line failure of leakage switch or equipment, and pass through size of current of the human body into common ground and depend on
The internal resistance of the person, such as personal internal resistance are 1000 Ω, 1000 Ω of equipment ground resistance, and voltage passes through the electric current of human body in 220V
It is then 110mA, the safe current 30mA that remote superman's physical efficiency is born.Such as electric shock and the children's water of Household sanitary electric heater bathing
Pond electric shock thing etc..
2, Line To Line gets an electric shock
When transmission cable damage in insulation, and when damage location is connected from different conductors respectively, when people directly or indirectly connects
It touches the conductor (metal or liquid such as water), constitutes circuit, electric current is from a phase transmission line → conductor → human body → another conductor → another
One transmission line generates electric shock accidents.For the line voltage of 380V, the loop resistance of 2000 Ω, then electric current is 190mA.Due to electricity
Stream inflow and outflow is equal, and leakage switch can not react.Even if can not also be protected equipped with overcurrent protective switch, because of general electric shock electricity
Stream is i.e. lethal in 1000mA or less, and the general overload protection of excess flow switch is in 5A or more.
It can be seen that being had the following problems at present by the power supply system of IEC standard and the reason of electric shock accidents takes place frequently：
1, earth leakage protective can not be carried out to undesirable metal-back is grounded；
2, it can not fail to leakage switch and the personal safety value of earth leakage protective and limitation leakage current lower than 30mA is provided；
3, the conductor that can not two potential differences be higher than with safe voltage 36V provides the earth leakage protective of Line To Line；
4, alarm or truncation power supply can not be proposed with regard to charged metal and media such as water, when leakage switch fails for some reason.
It can be seen that above-mentioned existing power supply system is in terms of electrical shock protection safety, it is clear that there are still have it is insufficient with it is scarce
It falls into, and needs to be further improved.But have no that effective scheme is developed completion always for a long time, this is clearly related industry
The problem of person is suddenly to be solved.Therefore a kind of new low-voltage safety confession that can prevent personnel equipment and electric shock accidents occurs how is founded
Electric system, real to belong to one of current important research and development project, also becoming current industry pole needs improved target.
In view of the above problem existing for above-mentioned existing power supply system, the present inventor is based on being engaged in electric equipment products design system
Many years rich experiences and professional knowledge are made, and cooperates the utilization of scientific principle, is actively subject to research and innovation, it is a kind of new low to found
Safe power supply system is pressed, to improve general existing power supply system, keeps its safer practical.By constantly studying, designing, and
After being studied and improved repeatedly, the present invention having practical value is created finally.
Low-voltage safety power supply circuit system of the invention is mainly used for household, factory, public electricity consumption facility, pond, fountain
And the electrical equipment lower than 1000V in single-phase or 3 phase voltages place.The low-voltage safety power supply system refers to by power supply grid
This section of electrical equipment is arrived after decompression.
Summary of the invention
It is a primary object of the present invention to, overcome existing power supply system existing deficiency in terms of safety utilization of electric power, and mention
For a kind of new low-voltage safety power supply system, the technical problem to be solved is that in electrical equipment use process, if it happens
Fault and lead to a phase and when external conductive casing short circuit, even if personnel are connected to shell and ground, personnel will not be caused to get an electric shock funeral
Die accident.
Another object of the present invention is to, overcome existing power supply system existing deficiency in terms of safety utilization of electric power, and mention
For a kind of new low-voltage safety power supply system, the technical problem to be solved is that leaked in power supply process if two phase lines occur
Electricity will not cause personnel's electric shock accidents.
Another object of the present invention is to, overcome existing power supply system existing deficiency in terms of safety utilization of electric power, and mention
For a kind of new low-voltage safety power supply system, which can detect the leak current fault of electrical equipment at any time, provide timely maintenance.
The object of the invention to solve the technical problems adopts the following technical solutions to realize.It proposes according to the present invention
A kind of low-voltage safety power supply system, including step-down transformer, power transmission line, earth leakage circuit-breaker and electrical equipment, wherein be equipped with
Isolating transformer, the armature winding of the isolating transformer connect the output of the step-down transformer, time of the isolating transformer
Grade winding connects electrical equipment by earth leakage circuit-breaker, and secondary windings neutral point, that is, zero curve of the isolating transformer is earth-free,
The power transmission line is the clad type power transmission line with conductive coating, and the conductive coating of the clad type power transmission line is electrically connected
The secondary windings neutral point of the isolating transformer.
The object of the invention to solve the technical problems also can be used following technical measures and further realize.
Low-voltage safety power supply system above-mentioned, wherein the isolating transformer is step-up transformer.
Low-voltage safety power supply system above-mentioned, wherein the isolating transformer is three-phase transformer or/and single-phase transformation
Device.
Low-voltage safety power supply system above-mentioned, wherein the clad type power transmission line includes the phase line with insulating layer, zero curve
And the conductive coating of the cladding phase line and zero curve, the outside of the conductive coating is insulating protective layer, and the zero curve is
Bare wire is electrically connected with the conductive coating.
Low-voltage safety power supply system above-mentioned, wherein the phase line of the clad type power transmission line is 3 or 1.
Low-voltage safety power supply system above-mentioned, wherein the metal shell of the electrical equipment and the isolating transformer are secondary
Micro-current earth detector is additionally provided between winding neutral point.
Low-voltage safety power supply system above-mentioned, wherein the micro-current earth detector be surveyed minimum current be less than
The micro-current earth detector of 30mA, the micro-current earth detector include：Low current sensor, microprocessor, report
Alarm device, interface circuit and electric-controlled switch, the input terminal of the low current sensor connect respectively electrical equipment external conductive casing and
The neutral point of isolating transformer secondary windings, the output of the low current sensor connect the input terminal of microprocessor, microprocessor
Output the electric-controlled switch, warning device are connect by the interface circuit.
Low-voltage safety power supply system above-mentioned, wherein the electric-controlled switch is relay or electronic switch；The alarm dress
Set is phonetic alarm or/and flash alarm.
Low-voltage safety power supply system above-mentioned, wherein the output of the microprocessor connects Ethernet controlling terminal.
Low-voltage safety power supply system above-mentioned, wherein the conductive coating of clad type power transmission line is wire mesh.
Low-voltage safety power supply system of the invention, has the following advantages that：
1, low-voltage safety power supply system provided by the invention, increases between step-down transformer and electrical equipment and transformation is isolated
Device, and the isolating transformer secondary windings neutral conductor does not access common ground, the phase line of isolating transformer secondary windings zero electricity over the ground
Pressure, is equivalent to the current loop to have broken between the earth from power supply unit lateral incision, can be avoided the circuit event in electrical equipment
External conductive casing electric leakage occurs for barrier, and due to being not switched on common ground, that is, making one contact electric leakage shell can not also be returned by human body
To isolating transformer secondary windings neutral point, to effectively prevent line to get an electric shock over the ground and lead to the generation of human body casualty accident.Drop
The secondary windings neutral ground of pressure transformer, i.e. the neutral point of the armature winding of isolating transformer is ground connection, once electricity consumption
Device housings short circuit, power supply pass through the high impedance of isolating transformer, and leakage current is also in the safe range of 30mA.It is general to become
Capacitor is 0.001 microfarad between the primary and secondary of depressor, then impedance is 30 kilo-ohms, and for the phase voltage of 220V, then maximum leakage current is only
For 7mA, it is much smaller than 30mA human-body safety electric current.
2, low-voltage safety power supply system provided by the invention connects the transmission line between isolating transformer and electrical equipment
Cable, using clad type power transmission line, each phase power transmission line and zero curve of mutually insulated are coated on and are led by the clad type power transmission line
In electro-cladding layer, if leaked electricity between line and line, excess flow switch only can be triggered, even if excess flow switch fails, short circuit current is only
Closed-loop flow without relating to outside in isolating transformer secondary windings, so as to avoid human body while contacting two phase lines, and
The human injury's accident for causing Line To Line to get an electric shock, has prevented the electric shock hidden danger of line and line, has further improved the power supply system
Safety.
3, micro-current detection of electrical leakage is further arranged in low-voltage safety power supply system provided by the invention in the power supply system
Device, (such as water Pie's is micro- for the metal shell or conductive medium of detection the isolating transformer secondary windings neutral conductor and each electrical equipment
Electric current, convenient in the case where no danger of electric shock and alarm is to handle.Further in the primary setting electricity of isolating transformer
Control switch, once the small leakage current for measuring certain numerical value is immediately controlled electric-controlled switch and cuts off the power；Further it can will also leak electricity
Information uploads Ethernet controlling terminal, realizes long-range control.
4, low-voltage safety power supply system provided by the invention can also be become before accessing electrical equipment by boosting isolation
Depressor carries out boosting processing, carries out power transmission with high voltage, can reduce power consumption, in the condition of same transmission power,
Transmission electric current can be reduced, reduce the heat of cable and joint, dramatically reduce the generation of fire alarm.Due to the electric current of transmission
Reduce the conducting wire that more small bore can be used, or even (such as used iron instead of copper) with the better material of higher electric resistivity intensity, can be saved
Expensive copper material.
The above description is only an overview of the technical scheme of the present invention, in order to better understand the technical means of the present invention,
Content and purpose, it is special below to lift preferred embodiment, and be described in detail with the accompanying drawings as follows.
Detailed description of the invention
It, below will be to specific in order to illustrate more clearly of the specific embodiment of the invention or technical solution in the prior art
Embodiment or attached drawing needed to be used in the description of the prior art be briefly described, it should be apparent that, it is described below
Attached drawing is some embodiments of the present invention, for those of ordinary skill in the art, before not making the creative labor
It puts, is also possible to obtain other drawings based on these drawings.
Fig. 1 is the circuit diagram of existing three phase and four wire circuit system.
Fig. 2 is the schematic diagram of low-voltage safety power supply system of the present invention.
Fig. 3 is the schematic diagram that the single-phase cladding transmission line of the present invention connects electrical equipment by socket.
Fig. 4 is the structural schematic diagram that three-phase of the present invention with zero curve coats transmission line.
Fig. 5 is the structural schematic diagram of the single-phase cladding transmission line of the invention with zero curve.
Fig. 6 is the structural schematic diagram of the micro-current earth detector in low-voltage safety power supply system of the present invention.
Specific embodiment
Technical solution of the present invention is clearly and completely described below in conjunction with attached drawing, it is clear that described implementation
Example is a part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, ordinary skill
Personnel's every other embodiment obtained without making creative work, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that term " first ", " second ", " third " are used for description purposes only,
It is not understood to indicate or imply relative importance.
As long as in addition, the non-structure each other of technical characteristic involved in invention described below different embodiments
It can be combined with each other at conflict.
It should be noted that the technical solution in the present invention, the neutral conductor of isolating transformer and common ground are disconnected, tool
Body, for single-phase isolating transformer, the neutral conductor is earth-free；For three-phase isolation transformer, in three-phase four-wire system
Circuit in, the neutral conductor is earth-free.The connection between the neutral conductor and common ground by disconnecting isolating transformer, is equivalent to
The current loop between power supply line and the earth is disconnected, the harm of electric shock is fundamentally avoided.
In addition, being described in the embodiment of the present invention, is all applicable in single-phase and three-phase electrical transmission, of the invention real
It applies in being described below of example, is mainly described in detail based on three-phase electricity.
As shown in Fig. 2, the present invention provides a kind of low-voltage safety power supply system, including step-down transformer 1, power transmission line 2, electric leakage
Protective switch 3 and electrical equipment 4, wherein being additionally provided with isolating transformer, the isolating transformer includes 7 He of three-phase isolation transformer
The armature winding of single-phase isolating transformer 8, the three-phase isolation transformer 7 and single-phase isolating transformer 8 connects the downconverter
The secondary windings of the output of device 1, the isolating transformer connects electrical equipment 4, the isolating transformer by earth leakage circuit-breaker 3
Secondary windings neutral point, that is, zero curve it is earth-free.
The step-down transformer 1 is three-phase transformer, time of the step-down transformer 1 and the three-phase isolation transformer 7
Grade winding is Y type three-phase four-wire system connection, and three phase lines of the armature winding 71 of three-phase isolation transformer 7 connect decompression respectively and become
Three output phase lines of depressor 1.The zero curve of the secondary windings 72 of three-phase isolation transformer 7 is earth-free.
The armature winding of single-phase isolating transformer 8 connects a phase line and zero curve for 1 secondary windings of step-down transformer respectively.It is single
Two output ends for isolating the secondary windings of transformer 8 are earth-free, and directly order phase electrical appliance.
In the case where there are three phase electric equipment and single-phase electric devices at the same time, a three-phase and four-line isolation can also be used
Transformer, the neutral conductor and ground wire of secondary windings disconnect, and three phase lines and the neutral conductor of secondary windings are used with three-phase respectively
Electric equipment is connected with single-phase electric devices provides power supply.
The power transmission line 2 is the clad type power transmission line 20 (ginseng Fig. 4, Fig. 5) with conductive coating, the clad type transmission of electricity
Line 20 includes the conductive coating 23 of the phase line 21 with insulating layer, zero curve 22 and the cladding phase line 21 and zero curve 22, described
Zero curve 22 is that bare wire is electrically connected with the conductive coating.
In three phase electric equipment, clad type power transmission line 20 used is 3 phase lines 21 and one and conductive coating
The zero curve 22 of connection is constituted.And the conductive coating 23 of the clad type power transmission line is electrically connected the isolation by zero curve 22
The secondary windings neutral point of transformer 7.
In single-phase electric devices, clad type power transmission line used is that 1 phase line 21 and one connect with conductive coating
The zero curve 22 connect is constituted.And the conductive coating 23 of the clad type power transmission line is electrically connected the isolation by zero curve 22 and becomes
An output line in the secondary windings of depressor 8.Actual use is generally by plugs and sockets wiring, as shown in figure 3, existing
There are three jacks, i.e. phase line jack 91, zero line jack 92 and ground connection line jack 93 for single-phase socket 9.In low-voltage safety of the invention
In power supply system, earth jack 93 is earth-free, and 91 phase-connecting wire 21 of phase string holes, zero line jack 92 connects zero curve 22.The ground hole 93
It connect, i.e., is connect with the conductive coating 23 of clad type power transmission line with the zero line jack 92.
By disconnecting the connection being isolated between the transformer secondary output winding neutral conductor and ground wire in low-voltage safety power supply system, i.e.,
The neutral conductor of isolating transformer secondary windings does not access common ground, and the phase line of isolating transformer secondary windings cannot be formed over the ground
Circuit has been broken the current loop between the earth from power supply unit lateral incision, once circuit or part in electric appliance or equipment, because of length
Time use is corroded or quality problems, and electric appliance or equipment leakage occurs, due to being not switched on common ground, leakage current without
Method connects the earth by human body, to prevent the generation because of human body casualty accident caused by getting an electric shock.
Due to the secondary windings neutral ground of step-down transformer, i.e. the neutral point of the armature winding of isolating transformer is to connect
Ground, once electrical equipment shell short circuit, power supply pass through the high impedance of isolating transformer, leakage current is also in the safety of 30mA
In range.Capacitor is 0.001 microfarad between the primary and secondary of general transformer, then impedance is 30 kilo-ohms, for the phase voltage of 220V,
Then maximum leakage current is only 7mA, is much smaller than 30mA human-body safety electric current.
It is the structure chart of clad type power transmission line in this present invention shown in Fig. 4, Fig. 5, wherein Fig. 4 is three-phase and four-line clad type
Power transmission line, the power transmission line include three phase lines 21, zero curve 22, conductive coating 23 and are coated on the first of the outside of every phase line 21
Insulating layer 24, the zero curve 22 are bare wire, and the conductive coating 23 coats all first insulating layers 24 and zero curve 22, in described
The outside of conductive coating 23 is coated with second insulating layer 25.The low-voltage safety power supply system of embodiment as shown in connection with fig. 2, this is low
Pressure safe power supply system is three phase supply, and corresponding to the transmission cable in Fig. 4, three phase lines 21 are respectively used to transmission isolation transformation
The three-phase voltage of device secondary windings, the zero curve being connected with conductive coating 23 is for connecting in isolating transformer secondary windings
Property point.
The clad type power transmission line connected between isolating transformer and electrical equipment in the present embodiment uses the three of mutually insulated
Root phase line 21 and the conductive coating 23 for being connected to zero curve 22 for being coated on three phase lines, 21 outside carry out power transmission.This implementation
Transmission cable in example uses clad type power transmission line, and all phase lines and zero curve are wrapped in conductive coating 23, sharp when having
Needle-like conductive body when piercing through the power transmission cable and reaching a certain phase line, be centainly also turned on zero curve, i.e. conductive coating, constitute
Short-circuit power circuit can trip because of short circuit, cut off the power when overcurrent protective switch is normal.Even if in overcurrent protective switch event
In the case of barrier, because of isolating transformer secondary windings isolated neutral, it also can be avoided human contact's phase and occur relatively
Electric shock accidents.If contacting two clad type power transmission lines pierced through by electric conductor simultaneously, what is contacted with the external world can only be zero curve, no
The electric shock accidents between Line To Line may occur, further improve the safety of the low-voltage safety power supply system.
In the present embodiment, conductive coating 23 is metal net shaped braiding layer or conductive membrane layer.
In the present embodiment, it can also be not provided with the zero curve 23 in the cladding region of conductive coating 23, only set
It is equipped with phase line, and the conductive coating 23 is used as zero curve simultaneously.For the three-phase and four-line electricity system or single line of three-phase imbalance
The permission electric current of electricity consumption, the conductive coating as zero curve need to meet actual needs.
In the present embodiment, it when the clad type power transmission line is used for transmission single-phase electricity, only needs to be arranged in transmission cable
A piece phase line 21 is coated on 21 outside of phase line as shown in figure 5, clad type power transmission line at this time is a phase line 21
The first insulating layer 24 and be coated on the conductive coating 23 in the outside of the first insulating layer 24.
In the embodiment of Fig. 2 low-voltage safety power supply system of the present invention, the metal shell 6 for stating electrical equipment is isolated with described
It is additionally provided with micro-current earth detector 10 between transformer secondary output winding neutral point, for detecting isolating transformer secondary windings
Leakage current between the metal shell of electrical equipment.
The micro-current earth detector 10 is that surveyed minimum current is micro-current earth detector less than 30mA,
Its structure is as shown in fig. 6, include：It low current sensor 11, microprocessor 12, warning device 13, interface circuit 14 and automatically controlled opens
15 are closed, the input terminal of the low current sensor 11 connects the external conductive casing 6 and isolating transformer secondary windings of electrical equipment respectively
Neutral point, the output of the low current sensor 11 connects the input terminal of microprocessor 12, and the output of microprocessor 12 passes through institute
It states interface circuit 14 and connects the electric-controlled switch 15 and warning device 13.
The low current sensor 11 is photoelectrical coupler or punching electromagnetic coupler etc..
The warning device 13 is phonetic alarm or/and flash alarm.
See that Fig. 2, Fig. 6, the electric-controlled switch 15 are set between the armature winding and step-down transformer of isolating transformer, are used for
Cut off isolating transformer power supply.
When the metal shell 6 of electrical equipment charges, micro-current is formed by from metal shell and flows through low current sensor,
The secondary windings neutral point for returning to isolating transformer returns to electricity consumption by the transmission phase line between secondary windings and electrical equipment and sets
It is standby, form the circuit of leakage current.
After low current sensor 11 detects micro-current, signal is sent to microprocessor 12, microprocessor 12 passes through interface electricity
Road controls electric-controlled switch and disconnects, to cut off the power supply of isolating transformer.The electric-controlled switch can be relay, can also use it
He can be automatically controlled electronic switch, only need to guarantee the cooperation of microprocessor and switch when detection device detects micro-current, can
Cut off the power supply of isolating transformer.
The microprocessor 12 also triggers the work of warning device 12, issues alarm with acousto-optic call user's attention.Optionally,
Warning device 12 can be individual buzzer, can also with Glittering illuminator, or a combination of both.The micro-current detection of electrical leakage dress
Warning message is also sent to Ethernet controlling terminal 16 by network by the microprocessor 12 set, and grasps low pressure in real time convenient for user
The working condition of safe power supply system.
As a kind of optional way of the present embodiment, connected between the metal shell 9 and each transmission phase line of electrical equipment
Have examination eletric button, by examination eletric button can the periodic detection low-voltage safety power supply system reliability.
It should be noted that the low-voltage safety power supply system in the embodiment of the present invention can be applied to factory (three-phase electricity and
It is single-phase), it also can be applied to residential quarter, mansion or family (single-phase), can be used in public electricity-using facility.
Low-voltage safety power supply system provided by the invention, also can be used boosting isolating transformer, so that output voltage increases,
And using clad type power transmission line carry out power transmission so that under power convey electric current become smaller, reduce power transmission line section, reduce at
This, thermal losses is greatly reduced；Pass through the three-phase voltage that step-down isolation transformer reduces to normal use again to distribution box front end,
In the low-voltage safety power supply system, the earth-free isolating transformer of the neutral conductor is on the one hand used, on the other hand uses transmission line
Cable carries out power transmission, avoids even if touching a wherein phase line in addition, will not cause electric shock, degree of safety is very high.
Obviously, the above embodiments are merely examples for clarifying the description, and does not limit the embodiments.It is right
For those of ordinary skill in the art, can also make on the basis of the above description it is other it is various forms of variation or
It changes.There is no necessity and possibility to exhaust all the enbodiments.And it is extended from this it is obvious variation or
It changes still within the protection scope of the invention.
Claims (10)
1. a kind of low-voltage safety power supply system, including step-down transformer, power transmission line, earth leakage circuit-breaker and electrical equipment, special
Sign is：Equipped with isolating transformer, the armature winding of the isolating transformer connects the output of the step-down transformer, the isolation
The secondary windings of transformer meets electrical equipment, secondary windings neutral point i.e. zero of the isolating transformer by earth leakage circuit-breaker
Line is earth-free, and the power transmission line is the clad type power transmission line with conductive coating, and the conductive of the clad type power transmission line is wrapped
Coating is electrically connected the secondary windings neutral point of the isolating transformer.
2. low-voltage safety power supply system according to claim 1, it is characterised in that the isolating transformer is boosting transformation
Device.
3. low-voltage safety power supply system according to claim 1, it is characterised in that the isolating transformer is three phase-change pressures
Device or/and single-phase transformer.
4. low-voltage safety power supply system according to claim 1, it is characterised in that the clad type power transmission line includes having
Phase line, zero curve and the conductive coating for coating the phase line and zero curve of insulating layer, the outside of the conductive coating are insulation
Protective layer, the zero curve are that bare wire is electrically connected with the conductive coating.
5. low-voltage safety power supply system according to claim 1, it is characterised in that the phase line of the clad type power transmission line is 3
Root or 1.
6. low-voltage safety power supply system according to claim 1, it is characterised in that the metal shell of the electrical equipment with
Micro-current earth detector is additionally provided between the isolating transformer secondary windings neutral point.
7. low-voltage safety power supply system according to claim 6, it is characterised in that the micro-current earth detector is
Surveyed minimum current is the micro-current earth detector less than 30mA, and the micro-current earth detector includes：Micro-current
The input terminal of sensor, microprocessor, warning device, interface circuit and electric-controlled switch, the low current sensor connects use respectively
The external conductive casing of electric equipment and the neutral point of isolating transformer secondary windings, the output of the low current sensor connect microprocessor
Input terminal, the output of microprocessor connects the electric-controlled switch, warning device by the interface circuit.
8. low-voltage safety power supply system according to claim 7, it is characterised in that the electric-controlled switch is relay or electricity
Sub switch；The warning device is phonetic alarm or/and flash alarm.
9. low-voltage safety power supply system according to claim 7, it is characterised in that the output of the microprocessor connects ether
Net controlling terminal.
10. low-voltage safety power supply system according to claim 1, it is characterised in that the conductive coating of clad type power transmission line
It is wire mesh.
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| CN112290415A (en) * | 2020-10-20 | 2021-01-29 | 任静 | Electric shock prevention intelligent power supply system |
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| CN108879673B (en) | 2024-08-27 |
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