JPS59127821A - Potential transformer - Google Patents

Abstract

PURPOSE:To suppress a fractional mode wave oscillation caused by iron resonance by connecting a suppression circuit, to which a suppression impedance component and an insulating transformer are provided, to the secondary circuit of a potential transformer. CONSTITUTION:A suppression circuit 6, which has a suppression impedance component 7 and an insulating transformer 8, is connected to the secondary circuit of a potential transformer 1 and a braking resistance R is used as the suppression impedance component 7. A transformation equipment is composed, in addition, of the primary winding 11 and the secondary winding 12 of the potential transformer 1, a core 13 of the potential transformer 1, the secondary terminals (u), (v), of the potential transformer 1, the primary winding 81 and the secondary winding 82 of the insulating transformer 8, a core 83 of the insulating transformer 8 and the like. Therefore, even if an electric impact is generated by the release of a circuit breaker 3, because the suppression circuit 6 is connected, in other words the braking resistance R as the suppression impedance component 7 is connected through the insulation transformer 8, to the secondary circuit of the potential transformer 1, a fractional mode wave oscillation caused by iron resonance is suppressed by the braking resistance R and the generation of abnormal voltage in the circuit of the potential transformer 1 is eliminated.

Description

[Detailed description of the invention] The present invention relates to an instrument voltage transformer.

For example, as shown in FIG. 1, a potential transformer 1 is connected to a power source 2 via a breaker 3.

In this case, if the breaker 3 is a capacitor 31 connected in parallel between the poles for voltage division or to improve breaking performance, when the breaker 3 is opened, the capacitor 31 of the breaker 3 and the bus bar 4 etc. Ground stray electrostatic field f? Ferro-resonance may occur in the circuit consisting of t5 and the circuit of the potential transformer 1. When this ferro-resonance occurs, an abnormal voltage will occur in the circuit of the A1 transformer 1 even though the circuit breaker 3 is opened, and there is a risk that the insulation of the A1 transformer 1 may be threatened. .

In view of the above-mentioned matters, this invention suppresses the occurrence of the above-mentioned ferro-resonance by connecting a suppression circuit having a suppression impedance component and an isolation transformer to the secondary circuit of a voltage transformer. It is.

An embodiment of the present invention will be explained below based on FIG. 2. In addition, parts given the same reference numerals as in FIG. 1 indicate the same or corresponding parts. 6 is the suppression impedance component 7
and an isolation transformer 8, the voltage transformer 1
Connect to the secondary circuit of

As the suppression impedance component 7, a braking resistance R as shown in FIG. 3A is used. 11 is the primary winding of the potential transformer 1; 12 is the secondary winding of the potential transformer 1;
3 is the iron core of the instrument transformer 1, u and y are the secondary terminals of the instrument transformer 1, 81 is the primary winding of the isolation transformer 8, 82 is the secondary winding of the isolation transformer 8, and 83 is the iron core of the isolation transformer 8.

According to the above configuration, even if an electric shock occurs due to the opening of the circuit breaker 3, the suppression impedance component 7 is transmitted to the secondary circuit of the transformer 1 via the suppression circuit 6, that is, the isolation transformer 8. Since the braking resistor R is connected, subharmonic vibration due to iron resonance is suppressed by the braking resistor R, and no abnormal voltage is generated in the circuit of the utility transformer 1.

When a series circuit of a saturable reactor L1 and a braking resistor R as shown in FIG. 3 is used as the suppressing impedance component 7, the magnetic flux density of the iron core of the saturable reactor L1 is When the value is set higher than that of the iron core 13 of the transformer 1, and subharmonic vibrations due to iron resonance occur due to the opening of the breaker 3, the
The saturable reactor l, 1 of the suppression circuit 6 is
The iron core should be saturated.

In addition, a capacitor C and a reactor L as shown in C of the same figure
A circuit in which a parallel circuit with 2 and a braking resistor R are connected in series,
Using the above parallel circuit capacitor t=LII? hLI
1. TQLl+1.5! ! mtE5! ! 1trr”ir
If it is set so that it resonates in parallel at the i-east frequency and has a low suppressing impedance against subharmonic vibration due to iron resonance, it is convenient because it does not put a burden on the voltage transformer 1 at all times. In this case, the parallel resonant circuit may be directly connected to the secondary circuit of the instrument transformer 1 without using the isolation transformer 8. Furthermore, the suppression impedance component 7 may be configured by any combination of two circuits.

Further, part or all of the winding of the saturable reactor L1 or the primary or secondary winding of the isolation transformer 8 is formed with a winding having a desired resistance value, and this winding resistance itself is used as the braking resistance. It may be used instead of R. Also, the value of the braking resistance R cannot be determined generally, but
It may be determined by considering the values of the capacitor 31 and the ground stray capacitance 5.

Next, another embodiment of the present invention shown in FIG. 4 will be described. In the illustrated example, the present invention is applied to a three-phase circuit, and a three-phase voltage transformer is connected to VI
JLC-V6) nl 1 frpu LL anger αl-”AL
An isolation transformer 8 connected to TI+oven delta is provided,
Suppressing impedance component 7 between its oven delta terminals
A three-phase finger-shaped suppression circuit 6 is connected.

By the way, instrument transformers used for effective grounding systems usually do not have a tertiary winding, and it is difficult to connect the secondary winding to an oven delta in such a transformer. According to the above-described configuration according to the present invention, since the isolation transformer 8 is used, an oven delta connection circuit is formed in the secondary circuit of the instrument transformer 1, and the suppressed impedance component 7 is formed between the oven delta terminals. Since it can be connected, it is particularly effective in suppressing subharmonic vibration due to iron resonance in a three-phase circuit.

Next, still another embodiment of the invention shown in FIGS. 5 and 6 will be described. The example shown in FIG. 5 shows a case where the present invention is applied to a three-phase circuit configured with three single-phase potential transformers, and the suppressing impedance component 7 is The next circuit has a star connection on the primary side and a star connection on the secondary side, and the suppressing impedance component 7 of the oven delta circuit acts to suppress subharmonic vibrations due to iron resonance in the three-phase circuit, and The suppressing impedance component 7 has the effect of suppressing subharmonic vibration due to iron resonance even more reliably.

In the example shown in FIG. 6, the magnetic flux density of the core of the isolation transformer 8 is set to a value higher than the magnetic flux density of the core of the voltage transformer 1, and when subharmonic vibrations due to iron resonance occur, the magnetic flux density of the core of the voltage transformer 1 is The isolation transformer 8 is saturated first, and the suppression circuit 6 is constructed by connecting a braking resistor R in series with the primary winding of the isolation transformer 8.

Further, a switch 9 is provided between the secondary circuit of the utility transformer 1 and the suppression circuit 6, so that the suppression circuit 6 can be disconnected when necessary, such as during an overvoltage test of the instrument transformer 1. be.

Further, similar to the embodiment shown in FIG. 5, the suppressing impedance component 7 is also connected between the secondary windings of the isolation transformer 8, and the suppressing circuit 6 as a whole is made into a unit, which is convenient for attachment to the equipment. It goes without saying that the insulating transformer 8 may be constructed with independent cores for each phase, or a three-phase insulating transformer may be constructed with one core such as a five-legged core.

As described in detail, according to the present invention, with an extremely simple configuration, fractional tuning due to ferroresonance of a potential transformer connected to a power source via a circuit breaker having capacitors connected in parallel between its poles can be achieved. It has the effect of suppressing wave vibration.

This invention is especially applicable when an 11-pot transformer is used in so-called GIS, which is made up of a breaker in which a capacitor for voltage division or to improve breaking performance is connected in parallel between poles, and other electrical equipment is gas-insulated. effective.

[Brief explanation of drawings]

Figure 1 is a circuit diagram explaining the case where ferroresonance occurs, Figure 2
The figure is a circuit diagram showing one embodiment of the present invention, FIG. 3 is a circuit diagram showing different examples of suppressing impedance components, and FIGS. 4 to 6 are circuit diagrams showing other different embodiments of the present invention. It is a diagram. 1: 51 power transformer, 2: power supply, 3: breaker, 31:
capacitor, 6: suppression circuit, 7: suppression impedance component, 8: isolation transformer, R: braking resistance, Ll: saturable reactor, C: capacitor, ■,: reactor. Patent applicant Nissin Electric Co., Ltd. Representative Masakatsu Yamawaki Drawing c”); Knee heart (no change in content) 1
Diagram 7 Gu L-1←Deaf g3 Otsuka 3 Diagram 'Xa Diagram 5 Diagram A Procedural Amendment (Method) 1982 Ketsu, ? ρ Date Patent Application No. 3732, filed in 1982 2. Name of the invention 1. Power transformer 3. Relationship with the person making the amendment Patent applicant Postal code 615 Address 47 Umezu Takaune-cho, Ukyo-ku, Kyoto City Map 5. Contents of the amendment As per attached sheet. 10

Claims (1)

[Claims] An instrument transformer formed by connecting a suppression circuit comprising a suppressing impedance component and an isolation transformer to the secondary circuit of an instrument transformer connected to a power supply via a breaker formed by connecting a capacitor in parallel between ti and ti. Device.