JPH079041U - Zero-phase voltage detector connected to an insulator capacitor - Google Patents

Abstract

(57) [Abstract] [Structure] Insulator capacitor connected to distribution line (1)
(2) In the zero-phase voltage detector provided between (3) and the ground (E), a voltage dividing capacitor (6) connected in series with the insulator capacitors (1), (2) and (3) and a voltage dividing capacitor ( The matching transformer (8) provided with an intermediate tap on the primary side for extracting the divided voltage of 6), the simulated voltage dividing capacitor (7) connected to the intermediate tap of the matching transformer (8), and the matching transformer (8). A simulation capacitor (5) simulating the insulator capacitors (1), (2) and (3) is provided on the intermediate tap. [Effect] In a ground fault direction relay installed at 6600V of a general high voltage distribution line, a large current ground fault characteristic test and other tests can be performed in a low voltage region of less than 600V obtained by stepping up / down a general commercial power source. it can. In addition, no special test personnel are required, and anyone having general electrical engineering knowledge can easily perform the test.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a zero-phase voltage detector that applies a zero-phase voltage to an installed ground fault direction relay, and in particular, to enable generation of a simulated zero phase voltage for testing of a ground fault direction relay, and The present invention relates to a zero-phase voltage detector of this kind which enables a high current ground fault characteristic test to be carried out in a low voltage region.

[0002]

[Prior art]

Earth fault directional relay DGR installed in distribution line, zero-phase current signal I _Z and the zero-phase electricity by the ZCT and the zero-phase voltage detector 4 provided in the path of the distribution line, as shown in FIG. 4 The pressure signal E _Z determines whether the ground fault is on the power supply side or the load side at the boundary of the zero-phase current transformer ZCT at the time of the ground fault, and when the ground fault is on the load side, the protection operation is performed.

Usually, this ground fault direction relay is subjected to a periodic test once or more a year. In this test, conventionally, the applied voltage to the zero-phase voltage detector has been made in a high voltage range exceeding 600V. For this reason, there is a zero-phase detector disclosed in Japanese Utility Model Laid-Open No. 62-111740 as a solution capable of performing a test in a low voltage region for the purpose of availability of power source and simplification of test work. This can be tested by applying a low voltage of less than 600 V to the test terminal by setting the capacity of the simulated capacitor to 1.3 to 10 times the capacity of the insulator capacitor.

[0004]

[Problems to be solved by the device]

 As a standard relating to this device, there is a Japanese Industrial Standard JISC4609 high voltage power receiving ground fault direction relay device, in which various operation confirmation items are set. There is an item called a large current ground fault characteristic test in this standard, and it is specified that 3810V (11430V for each phase) is applied collectively to the high voltage side three phases of the insulator capacitor in consideration of the one-wire complete ground fault. .

In the device disclosed in Japanese Utility Model Laid-Open No. 62-111740, a voltage of 1143 V is applied to the test terminal T in the large current ground fault characteristic test. For this reason, the voltage exceeds 600 V, which means that high voltage is handled, and a high-voltage product such as a test device and an electric wire to be used is used, resulting in a problem that workability is deteriorated.

The problem to be solved by the present invention is to provide a zero-phase voltage detector capable of applying a low voltage of 600 V or less even in a large current ground fault characteristic test.

[0007]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention provides a zero-phase voltage detector provided between an insulator capacitor connected to a distribution line and ground, and a voltage dividing capacitor connected in series with the insulator capacitor, and a voltage dividing capacitor of the voltage dividing capacitor. A matching transformer with an intermediate tap on the primary side for extracting the divided voltage, a simulated voltage dividing capacitor connected to the intermediate tap of the matching transformer, and a simulated capacitor simulating the insulator capacitor are provided on the intermediate tap of the matching transformer. It is a thing.

In this zero-phase voltage detector, the winding ratio of the center tap of the matching transformer is set to 1/3 or less of the total number of turns, and the capacity of the simulated capacitor is set to 1.2 times or less of the capacity of the insulator capacitor. You can

Another means for solving the above-mentioned problems is a zero-phase voltage detector provided between an insulator capacitor connected to a power distribution line and ground, and a voltage dividing capacitor connected in series with the insulator capacitor. And a simulated voltage dividing capacitor, a matching transformer for extracting the divided voltage of the voltage dividing capacitor and the simulated voltage dividing capacitor, and a simulated capacitor simulating the insulator capacitor at the connection point of the voltage dividing capacitor and the simulated voltage dividing capacitor. Is provided.

In this zero-phase voltage detector, the capacity of the simulated capacitor can be set to 20 times or more the capacity of the insulator capacitor.

[0011]

[Action]

 In the first method, a matching transformer with an intermediate tap is used to boost the test voltage, so that a specified large-current ground fault characteristic test can be performed at a low test voltage.

Further, in the second means, the matching transformer is provided with the voltage dividing capacitor and the simulated voltage dividing capacitor in parallel to boost the capacitor, and similarly to the first means, the test voltage of the low voltage is used for the regulation. The large current ground fault characteristic test can be performed.

[0013]

【Example】

Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. FIG. 1 shows an embodiment of the present invention, in which 1,2,3 are insulator capacitors, 4 is a zero-phase voltage detector, 5 is a simulated capacitor, 6 is a voltage dividing capacitor, and 7 is a simulated voltage dividing capacitor. , 8 is a matching transformer, T is a test terminal, y ₁ and y ₂ are output terminals, E is a ground part, DGR is a ground fault direction relay, and ZCT is a zero-phase current transformer.

In this embodiment, an intermediate tap is provided on the primary side of the matching transformer 8 at a position of 1/3 or less of the total number of turns as viewed from the ground side, and the simulated voltage dividing capacitor 7 and the simulated capacitor 5 are provided on this intermediate tap. Connecting. Here, assuming that the capacity of the simulated capacitor 5 is 1.2 times the capacity of the insulator capacitor, the voltage dividing capacitor 6 and the simulated voltage dividing capacitor 7 have the same capacity, and the intermediate tap is 1/17 of the total number of turns, 1 If 6600 × √3 / 1.2 × 17 = 560V is applied between the test terminal T and the ground even if the voltage is 100% with respect to the line complete ground fault, it is applied to the terminals y ₁ and y ₂ of the matching transformer 8. specified voltage signal V _t is obtained. At this time, a voltage of about 24 V is output to the primary side of the matching transformer 8.

In another embodiment, the capacity of the simulated capacitor 5 is 1.2 times the capacity of the insulator capacitor, and the capacity of the simulated voltage dividing capacitor 7 is 67 times the capacity of the simulated capacitor 5, and the matching transformer is used. When the intermediate tap of 8 is 1/3 of the total number of turns, if a voltage of about 540V is applied between the test terminal T and the ground part, a voltage of about 24V is output to the primary side of the matching transformer 8, and the voltage of the matching transformer 8 is reduced. The specified voltage signal V _t is obtained at the secondary terminals y ₁ and y ₂ .

FIG. 2 shows another embodiment of the present invention. In this embodiment, the voltage dividing capacitor 6 and the simulated voltage dividing capacitor 7 are provided on the primary side of the matching transformer 8, and the simulated capacitor 5 is connected to the connecting portion. The capacitance ratio of the simulated capacitor 5 and the simulated voltage dividing capacitor 7 is set to 20 times the capacitance ratio of the insulator capacitors 1 to 3 and the [voltage dividing capacitor 6 + simulated voltage dividing capacitor 7], and the impedance of the primary side of the matching transformer 8 is increased. If the impedance of the dance + voltage dividing capacitor is made much larger than the simulated voltage dividing capacitor impedance, if 570V is applied between the terminal T and the ground even if the voltage is 100% of the complete ground fault voltage, the terminal of the matching transformer 8 The specified voltage V _t is obtained for y ₁ and y ₂ .

FIG. 3 is a circuit diagram for calculating the capacity C ₄ of the simulated capacitor 5 from the capacity of each capacitor in the circuit of FIG. 2, where C ₁ is the combined capacity of the three-phase insulator capacitors, and C ₂ is The capacity of the voltage dividing capacitor 6 and C ₃ indicate the capacity of the simulated voltage dividing capacitor 7. The impedance of the primary side of the matching transformer 8 is sufficiently large for each capacitance.

When V ₁ is applied between the U and W terminals and the E terminal, the primary side voltage V ₄ of the matching transformer 8 becomes as follows. V ₄ = V ₁ [C ₁ / {(C ₂ C ₃ ) / (C ₂ + C ₃ ) + C ₁ }]

On the other hand, when V ₂ is applied between the terminals T and E, the primary side voltage V ₄ of the matching transformer 8 becomes as follows. V ₄ = V ₂ {C ₄ / (C ₃ + C ₄ )}

In order to make V _{4 the} same when V ₁ is actually applied and when the voltage V ₂ is applied to the test terminal, V ₁ [C ₁ / {(C ₂ C ₃ ) / (C ₂ + C ₃ ) + C ₁ }] = V ₂ {C ₄ / (C ₃ + C ₄ )}

Further, when V ₁ = 11432V (= 6600√3) in the high current ground fault characteristic test, it is desired to set V ₂ ≦ 600V. Therefore, C ₁ / {(C ₂ C ₃ ) / (C ₂ + C ₃ ) + C ₁ } / {C ₄ / (C ₃ + C ₄ )} ≧ 20 By substituting the current values of C ₁ , C ₂ + C ₃ into this formula, the capacity ratio of C ₃ and C ₄ is set. Then, the value of C ₄ is obtained.

[0022]

[Effect of device]

 As described above, according to the present invention, in a ground fault direction relay installed at 6600V of a general high-voltage distribution line, a large current ground in a low voltage region of less than 600V obtained by stepping up / down a general commercial power source. It is possible to conduct a tangential property test and other tests. For this reason, the test apparatus does not require special test personnel, and anyone having general electrical technology knowledge can easily carry out the test, thus exhibiting excellent effects.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the first means of the present invention.

FIG. 2 is a circuit diagram showing an embodiment of the second means of the present invention.

FIG. 3 is a circuit diagram for calculating a capacitance in the embodiment of FIG.

FIG. 4 is a circuit diagram of a conventional example.

[Explanation of symbols]

1,2,3 Insulator capacitors, 4 Zero phase voltage detector, 5
Simulated capacitor, 6 voltage dividing capacitor, 7 simulated voltage dividing capacitor, 8 matching transformer, T test terminal,
y ₁ and y ₂ output terminals, E ground section, DGR ground fault direction relay, ZCT zero phase current transformer, U, V, W charging section,
N Neutral point terminal

Claims (4)

[Scope of utility model registration request] 1. A zero-phase voltage detector provided between an insulator capacitor connected to a power distribution line and a ground, wherein a voltage dividing capacitor connected in series with the insulator capacitor and a primary voltage for extracting a divided voltage of the voltage dividing capacitor. A matching transformer provided with an intermediate tap on the side, and a simulated voltage dividing capacitor connected to the intermediate tap of the matching transformer,
A zero-phase voltage detector connected to an insulator capacitor, wherein the intermediate tap of the matching transformer is provided with a simulated capacitor simulating the insulator capacitor. 2. The winding ratio of the intermediate tap of the matching transformer is set to 1/3 or less of the total number of turns, and the capacity of the simulated capacitor is set to 1.2 times or less of the capacity of the insulator capacitor. Zero-phase voltage detector connected to an insulator capacitor. 3. A zero-phase voltage detector provided between an insulator capacitor connected to a power distribution line and a ground, wherein a voltage dividing capacitor and a simulated voltage dividing capacitor are connected in series with the insulator capacitor, and the voltage dividing capacitor and the capacitor. A matching transformer for extracting a divided voltage of the voltage dividing capacitor, and a simulation capacitor simulating the insulator capacitor is provided at a connection point between the voltage dividing capacitor and the simulated voltage dividing capacitor. Zero connected to the insulator capacitor. Phase voltage detector. 4. The zero-phase voltage detector connected to an insulator capacitor according to claim 3, wherein the capacity of the simulated capacitor is 20 times or more the capacity of the insulator capacitor.