CN2142574Y

CN2142574Y - Earth connection measuring apparatus for power system

Info

Publication number: CN2142574Y
Application number: CN 92238613
Authority: CN
Inventors: 孙爱军; 孙培壮; 孙云政; 王在惠; 于中章; 王晓峰
Original assignee: MOUPING COUNTY ELECTRICITY ADMINISTRATION
Current assignee: MOUPING COUNTY ELECTRICITY ADMINISTRATION
Priority date: 1992-10-29
Filing date: 1992-10-29
Publication date: 1993-09-22
Anticipated expiration: 2002-10-29

Abstract

The utility model relates to an earth connection measuring apparatus for the power system, belonging to the technical field of system detection of the power engineering. The earth connection measuring apparatus for the power system is composed of a signal detection alarm unit, a signal processing unit and a sum signal display unit. The signal detection alarm unit is composed of a voltage transformer, a zero sequence current transformer which is connected with a circuit, a sampling resistor and an alarm bell. After an earth connection fault occurs, the zero sequence current transformer can generate the zero sequence current. The user can easily determine which circuit is connected with the earth by observing the size of the electric current of a current meter and the brightness of an LED.

Description

Earth connection measuring apparatus for power system

The utility model relates to a kind of electric system ground detection device, belongs to power engineering system detection technique field.

In present supply network, mostly adopt neutral earth-free technology, in this method of operation, the electric system meeting is because of The Ageing of Insulators, former thereby generation earth fault such as substation transformer damage, owing to do not know it specifically is that earth fault has taken place which bar circuit, so the staff can only adopt the method that has a power failure of operating a switch to come detection failure, this detection mode has increased the maintenance number of times of high-voltage switch gear simultaneously, and power supply cost is risen.

The purpose of this utility model provides a kind of when earth fault appears in electric system, can show the ground detection device of the circuit that earth fault takes place automatically, to overcome the existing problem of prior art.

The utility model is achieved by the following technical solution, electric system ground fault detection device of the present utility model is by the input alarm unit, signal processing unit and signal display unit are formed, the input alarm unit is by the voltage transformer (VT) that links to each other with bus, the zero sequence current mutual inductor that links to each other with the transmission of electricity circuit, sample resistance and alarm bell are formed, and wherein sample resistance links to each other with the secondary side output terminal of zero sequence current mutual inductor, and alarm bell links to each other with voltage transformer (VT).When earth fault appearred in circuit, voltage transformer (VT) produced residual voltage and starts the alarm bell signal that warns.Simultaneously, earth fault changes the capacitance current of all line-to-grounds, destroyed the balance of capacitance current itself, thereby make and occurred zero-sequence current in the zero sequence current mutual inductor, this current signal offers signal display unit after by signal processing unit processes and shows, thereby which bar circuit generation earth fault just can demonstrate specifically be.

The utility model just can differently be found out the circuits that earth fault takes place, time saving and energy saving power saving with the left alone without help electricity of operating a switch by the zero-sequence current that detection is connected the zero sequence current mutual inductor generation in the circuit.

Below in conjunction with accompanying drawing, by way of example the utility model is described in detail.

Fig. 1 is the profile synoptic diagram of electric system ground detection device of the present utility model.

Fig. 2 is the principle of work block diagram of electric system ground detection device of the present utility model.

Fig. 3 is the electrical schematic diagram of an embodiment of electric system ground detection device of the present utility model.

Fig. 4 is the schematic cross-section of the zero sequence current mutual inductor in the electric system ground detection device of the present utility model.

With reference to Fig. 1,

dc milliammeter

2,3,4,5,6 and 7 is wherein arranged on the panel of earth connection measuring apparatus for power system 1, and

light emitting diode

8,9,10,11,12 and 13, be used for respectively 6 circuits being carried out earth fault and show. Certainly, the user can select the quantity of dc milliammeter and light emitting diode as required, only is to have provided an example here.

With reference to Fig. 2, Fig. 2 is operation principle block diagram of the present utility model, wherein when earth fault takes place in power system 14, signal detection alarm unit 15 detects the earth fault signal and reports to the police, simultaneously the earth fault signal is flowed to signal processing unit, signal processing unit is processed into the earth fault signal of importing and is suitable for signal that signal display unit shows so that the earth fault signal is shown. Here only told about the operation principle that the earth fault to a circuit detects, for many circuits, wherein the principle to the detection of the earth fault of every circuit all is identical, that is to say all signal detection alarm units of oneself of every circuit, signal processing unit and signal display unit, the quantity of their quantity and circuit is one to one.

Fig. 3 has represented an embodiment of the present utility model.Wherein by zero sequence current mutual inductor 18, voltage transformer (VT) 19, alarm bell 20 and sample resistance 21 have been formed input alarm unit 15, form signal processing unit 16 by bridge rectifier circuit 22, form signal display unit 17 by light emitting diode 23 and dc milliammeter 24.For clarity sake, only describe with regard to a circuit here, in fact every circuit has all been installed input alarm unit, signal processing unit and the signal display unit of being made up of above-mentioned parts.When singlephase earth fault had taken place transmission line of electricity, variation had just taken place in the capacitive earth current of all circuits, thereby had destroyed the balance of capacitance current itself, and promptly the vector sum of three phase capacitance electric current is not equal to zero.The capacitive earth current of all circuits all passes through earth point A and is flowed on the bus like this, promptly pass through zero sequence current mutual inductor 18, because the secondary side of zero sequence current mutual inductor 18 has had zero-sequence current, so the two ends at sample resistance 21 just can produce voltage, AC signal is processed into direct current signal and offers light emitting diode 23 and dc milliammeter 24 shows through bridge rectifier circuit.Simultaneously, voltage transformer (VT) 19 produces residual voltages and starts alarm bell 20 signal that warns.After the staff hears the signal of alarm bell, just can be bright by the light emitting diode 23 of checking any bar circuit, the reading of dc milliammeter 24 is big, just illustrates that earth fault has taken place which bar circuit.When system earth point A under the very near situation of transformer station, the zero-sequence current that zero sequence current mutual inductor produced may be not enough so that generating diode 23 is very bright, but at this moment dc milliammeter 24 also has tangible indication, and this has just guaranteed that under any circumstance signal display unit can both significantly show.

Fig. 4 is the schematic cross-section of the zero sequence current mutual inductor that adopted of electric system ground detection device 1 of the present utility model.Wherein on iron core 26, be wound with

coil

25,31, on the inwall of the square hole of iron core 26,

insulcrete

27,40 is housed, 41 and 42, three

conductors

28,35 and 39 are wherein arranged, be with glass fiber tube (29 in the outside of each conductor, 33 and 37), between conductor and corresponding glass fiber tube, epoxy resin layer (30,34 and 38) is arranged, and also be respectively arranged with

insulcrete

32 and 36 two of middle conductor.Thereby owing to be with the glass fiber tube on the conductor and casting epoxy resin and set up insulcrete between the conductor again and guaranteeing to have dwindled greatly under the situation of alternate reliable insulation distance between conductor between them, thereby it is little to make zero sequence current mutual inductor have a volume, the advantage of reliable in action sensitivity, and can on overhead transmission line, use.Simultaneously, because the zero sequence current mutual inductor volume that the utility model adopted is little.So input alarm unit of the present utility model, signal processing unit and signal display unit can be installed in the little shell of volume.

Claims

1, a kind of electric system ground detection device, form by input alarm unit, signal processing unit and signal display unit, it is characterized in that said input alarm unit is by the voltage transformer (VT) that links to each other with bus, the zero sequence current mutual inductor that links to each other with the transmission of electricity circuit, sample resistance and alarm bell are formed, wherein sample resistance links to each other with the secondary side output terminal of zero sequence current mutual inductor, and alarm bell links to each other with voltage transformer (VT).

2, according to the said electric system ground detection device of claim 1, it is characterized in that being with the glass fiber tube on the conductor of said zero sequence current mutual inductor, between conductor and glass fiber tube, epoxy resin layer is arranged, and between conductor, also be provided with insulcrete.