CN2741248Y

CN2741248Y - Zero line breaking preventor of transformer

Info

Publication number: CN2741248Y
Application number: CN 200420029921
Authority: CN
Inventors: 吴作明; 杨弘惟
Original assignee: Tianjin University of Technology
Current assignee: Tianjin University of Technology
Priority date: 2004-10-13
Filing date: 2004-10-13
Publication date: 2005-11-16
Anticipated expiration: 2014-10-13

Abstract

The utility model discloses a protection device, in particular relates to a preventor of the transformer used for the zero line breaking of the three-phase four-wire system. The primary side of a single-phase transformer is respectively connected between. Each phase wire end of the transformer connected with the three-phase four-wire system and the zero line end. The auxiliary side of each single-phase transformer is connected with a bridge rectifier; the output end of each bridge rectifier is respectively connected with one input end of each window comparator. The output end of a reference voltage adopted from another direct-current power supply is respectively connected with the other input end of each window comparator. The output end of each window comparator is connected with each input end of one or gate. The output end is connected with the driving circuit of a final control relay whose contact point can output protective actions. The utility model has the advantages of reliable protection and multifunctional protections of the broken circuit protection of the zero line, the open-phase protection and the interphase short circuit protection.

Description

Transformer zero line break protector

Technical field

The utility model belongs to protective device, particularly relates to a kind of transformer zero line break protector that is used for three-phase four-wire system.

Background technology

The utility model of publication number 2456350 " disconnected zero line protector "; a kind of protective device that is used for the three-phase four-wire system electrical appliance is disclosed; it constitutes disconnected zero testing circuit by being connected to the shared current transformer of zero line and phase line respectively; constitute control circuit by release, rectifier, one-way SCR, optical coupler and comparator, constitute actuator by the switch that is connected in release.Described disconnected zero line protector is that comparator is exported a pulse and triggered one-way SCR through optical coupler when unbalance electric current, zero line no current appear in phase line, and the one-way SCR of conducting makes release and switch motion, thereby cuts off the electrical appliance power supply.Though above-mentioned disconnected zero line protector has the certain protection effect for the harm that zero line break brought, and obviously has following defective: the phase failure and the various short troubles of three-phase transformer are not had protective effect, so defencive function is more single.

Summary of the invention

The utility model is in order to overcome the more single technical problem of defencive function that above-mentioned disconnected zero line protector exists, and proposes a kind of transformer zero line break protector that has open phase protection, phase fault defencive function concurrently.

The utility model is that the more single technical problem of defencive function that overcomes above-mentioned disconnected zero line protector existence is taked following technical scheme: transformer zero line break protector is by testing circuit; decision circuitry and executive circuit are formed; be connected to the former limit of the single-phase transformer of testing circuit between each phase line end of the transformer that three-phase four-wire system connects and the zero line side respectively; the secondary of each single-phase transformer is connected to bridge rectifier; the output of each bridge rectifier is an input of each window comparator of connection judgment circuit respectively; the reference voltage output end of taking from another DC power supply connects another input of each window comparator respectively; the output of each window comparator connect respectively one or the door each input; its output connects the drive circuit of the execution relay of executive circuit, carries out the closure of relay contact output control transformer circuit breaker; the disjunction control signal.

The utility model can also be taked following technical scheme;

The output of each bridge rectifier of described testing circuit is connected to filter capacitor respectively.

Described another DC power supply provides the external power supply of this protector operating voltage.

The window comparator of described decision circuitry is made of upper limit comparator, lower limit comparator and the NAND gate that is connected the upper and lower limit comparator output terminal, the NAND gate output connects respective input same or door, the output of each bridge rectifier of testing circuit connects the inverting input and the normal phase input end of upper and lower limit comparator respectively, and reference voltage output end connects the normal phase input end and the inverting input of upper and lower limit comparator respectively.

The beneficial effects of the utility model and advantage are: no matter zero line break appears in the transformer that output is connected to three-phase four-wire system, arbitrary phase line opens circuit and variation will take place for its zero line of short circuit and phase line, at least in each bridge rectifier or whole output voltages change, this moment the respective window comparator and or goalkeeper export high level, drive circuit makes to be carried out the actuating of relay and controls circuit breaker and cut off the electrical appliance power supply.The utlity model has zero line break protection, open phase protection and the multifunction protection and the reliably outstanding advantage of protection of short-circuit protection mutually.

Description of drawings

Accompanying drawing 1 embodiment electrical schematic diagram.

Accompanying drawing 2 example structure schematic diagrames.

Number in the figure: 1 housing, 2 panels, 3 external direct current power supply terminals, 4 terminal boards.

Embodiment

Further specify the utility model below in conjunction with embodiment and accompanying drawing thereof.

Embodiment as shown in Figure 1, constitute testing circuit of the present utility model by single-phase transformer T1, T2, T3 and bridge rectifier Z1, Z2, Z3 and filter capacitor C1, C2, C3, specifically be connected to the former limit of single-phase transformer T1, T2, T3 between each phase line end a, b, c and the zero line side n of 10KV/～400V three-phase transformer respectively, the secondary of each single-phase transformer is connected to bridge rectifier Z1, Z2, Z3, and the output of each bridge rectifier is connected to filter capacitor C1, C2, C3 respectively.

Constitute decision circuitry of the present utility model by discharge circuit U1-U6, NAND gate circuit U7, U8, U9 and OR circuit U10 among Fig. 1, wherein discharge circuit U1-U6, NAND gate circuit U7, U8, U9 constitute 3 window comparators of decision circuitry respectively.With discharge circuit U1, U2, U7 is that example illustrates its formation, wherein U1 is a upper limit comparator, U2 is the lower limit comparator, U1 inverting input and U2 normal phase input end are connected the output of bridge rectifier Z1 respectively through resistance R 6, R7, the U1 normal phase input end is connected the bleeder circuit that is made of resistance R 1, R3 and R2, R4 respectively through resistance R 5, R8 respectively with the U2 inverting input, its partial pressure value is a reference voltage, wherein resistance R 1, R3 partial pressure value are upper limit reference voltage, resistance R 2, R4 partial pressure value are the lower limit reference voltage, and each bleeder circuit is connected in external 12V DC power supply.Discharge circuit U1, U2 output connect NAND gate circuit U7 respective input respectively.

2 window comparators connect and compose as hereinbefore in addition, no longer repeat.

Among Fig. 1, NAND gate circuit U7, U8, U9 output connect the OR circuit U10 respective input of the utility model decision circuitry respectively.

Constitute executive circuit of the present utility model by transistor T 1 and execution relay K A among Fig. 1, specifically the output of OR circuit U10 connects transistor T 1 base stage through resistance R 17, is connected in the collector loop and carries out relay K A coil.Carry out relay and control the control signal that the circuit breaker of each phase line setting of three-phase transformer is cut off in contact output, its usage is a lot, for example connects (Fig. 1 are not shown) such as execution relay normally closed interlocks among Fig. 1 in the circuit breaker QF winding loop.

Provide among Fig. 1 this protector+the 12V operating voltage takes from external rectifying voltage regulator.

Summary Fig. 1 protects course of action as follows: open circuit to electrical appliance as zero line N; each phase voltage departs from normal value; cause bridge rectifier Z1, Z2, Z3 output voltage to change; as long as wherein there is one road output voltage changing value to surpass the upper limit or the lower range of window comparator; then this road window comparator NAND gate is exported high level; OR circuit U10 also exports high level; transistor T 1 conducting; carry out relay K A output and make the protection sexual act and cut off the transformer output that three-phase four-wire system connects, protected electrical appliance safety.

As certain alternate opening circuit among phase A, B, the C; this phase voltage and zero line N voltage deviation normal value; this corresponding bridge rectifier output voltage changes; then this road window comparator NAND gate is exported high level; OR circuit U10 also exports high level, and transistor T 1 conducting is carried out relay K A and also exported do protection sexual act; cut off the transformer output that three-phase four-wire system connects, protected three-phase electrical appliance safety.

Fig. 1 example structure shape as shown in Figure 2; testing circuit, decision circuitry and the executive circuit of this protector are set in the housing 1; the terminal that connects three-phase four-wire system connection transformer is set in the terminal board 4 of panel 2 and carries out the relay contact leading-out terminal, panel 2 tops are provided with external direct current power supply terminal 3.

Claims

1; transformer zero line break protector; by testing circuit; decision circuitry and executive circuit are formed; it is characterized in that: transformer zero line break protector is by testing circuit; decision circuitry and executive circuit are formed; be connected to the former limit of the single-phase transformer of testing circuit between each phase line end of the transformer that three-phase four-wire system connects and the zero line side respectively; the secondary of each single-phase transformer is connected to bridge rectifier; the output of each bridge rectifier is an input of each window comparator of connection judgment circuit respectively; the reference voltage output end of taking from another DC power supply connects another input of each window comparator respectively; the output of each window comparator connect respectively one or the door each input; its output connects the drive circuit of the execution relay of executive circuit, carries out the closure of relay contact output control transformer circuit breaker; the disjunction control signal.

2, protector according to claim 1 is characterized in that: the output of each bridge rectifier of described testing circuit is connected to filter capacitor respectively.

3, protector according to claim 1 is characterized in that: described another DC power supply provides the external power supply of this protector operating voltage.

4, protector according to claim 1; it is characterized in that: the window comparator of described decision circuitry is made of upper limit comparator, lower limit comparator and the NAND gate that is connected the upper and lower limit comparator output terminal; the NAND gate output connects respective input same or door; the output of each bridge rectifier of testing circuit connects the inverting input and the normal phase input end of upper and lower limit comparator respectively, and reference voltage output end connects the normal phase input end and the inverting input of upper and lower limit comparator respectively.