JP2014060891A - Instrument transformer faulty phase detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an instrument transformer faulty phase detection apparatus capable of detecting a faulty phase in the case where one phase of any one of two instrument transformers installed in two bus lines breaks down.SOLUTION: A faulty phase detection apparatus 10 comprises a faulty phase detection section 15 in which, when a fault in any one of first and second instrument transformers 3, 3is detected by a fault PD detection section 14, an absolute value of a difference between first and second U-phase, V-phase and W-phase instantaneous voltages U, V, W, U, V, Wis calculated to determine U-phase, V-phase and W-phase instantaneous voltage differences ΔU, ΔV, ΔW. A phase for which values resultant from dividing the determined U-phase, V-phase and W-phase instantaneous voltage differences ΔU, ΔV, ΔW with U-phase, V-phase and W-phase peak-peak voltages U, V, Wone cycle before are equal to or more than a predetermined value is determined as a faulty phase, and in the case where the resultant value are less than the predetermined value, a zero-phase is determined as a faulty phase.

Description

  The present invention relates to an instrument transformer fault phase detection apparatus suitable for detecting a fault phase when one phase of either one of two instrument transformers installed on two busbars fails.

  Conventionally, an electric power company is expensive because it cannot function as an instrument transformer unless it is duplicated as a countermeasure when a fault occurs in an instrument transformer (transformer, PD or GPT). It was.

Therefore, for example, in the instrument transformer disclosed in Patent Document 1 below, when the U-phase detection unit or the converter fails, the arithmetic circuit has a V-phase secondary output O _V and a W-phase secondary. The value obtained by subtracting the sum with the output O _W from the zero-phase secondary output O _Z (= O _Z − (O _V + O _W )) is output as the U-phase secondary output O _U , thereby providing excellent reliability. The detection unit and the converter are avoided from being duplicated while ensuring.
In this instrument transformer, if the sum of the secondary outputs of the U-phase, V-phase and W-phase (= O _U + O _V + O _W ) does not match the zero-phase secondary output O _Z , an alarm means is provided. By outputting an alarm, it is possible to quickly and easily determine the failure phase when any of the U phase, V phase, W phase, and zero phase of the instrument transformer has failed.

JP 2002-353051 A

  However, the instrument transformer disclosed in Patent Document 1 compares the sum of the U-phase, V-phase, and W-phase secondary outputs with the zero-phase secondary output and warns if they do not match. Since any of the U phase, V phase, W phase and zero phase can be detected, it is possible to detect any phase of U phase, V phase, W phase and zero phase. There is a problem that it cannot be detected whether or not the device is out of order.

  An object of the present invention is to provide an instrument transformer fault phase detection device capable of detecting a fault phase when one of two instrument transformers installed on two bus bars fails. There is to do.

The instrument transformer fault phase detection device according to the present invention has one of the first and second instrument transformers (3 ₁ , 3 ₂ ) installed on the first and second buses, respectively. An instrument transformer fault phase detection device (10) for detecting a fault phase when a fault occurs, wherein the first U phase, V phase and W phase instants output from the first instrument transformer Based on the voltage (U ₁ , V ₁ , W ₁ ) and the first zero-phase instantaneous voltage (Z ₁ ) output from the first instrument transformer, the failure of the first instrument transformer is determined. The second U-phase, V-phase and W-phase instantaneous voltages (U ₂ , V ₂ , W ₂ ) output from the second instrument transformer and output from the second instrument transformer the second zero-phase instantaneous voltage (Z ₂₎ and the instrument transformer failure detecting means for detecting a failure of the second instrument transformer based on being (1 And when the failure of either one of the first and second instrument transformers is detected by the instrument transformer failure detection means, the first and second U-phase, V-phase and W-phase The absolute value of the instantaneous voltage difference is taken to obtain the U-phase, V-phase, and W-phase instantaneous voltage differences (ΔU, ΔV, ΔW), and the obtained U-phase, V-phase, and W-phase instantaneous voltage differences are A phase in which the value divided by the phase, V phase, and W phase peak peak voltages (U _pp , V _pp , W _pp ) is greater than or equal to a predetermined value is determined as a failure phase, and all the divided values are the predetermined values. When it is smaller than the value, it comprises failure phase detection means (15) for determining the zero phase as a failure phase.
Here, the first and second buses constitute a double bus, and the instrument transformer fault detecting means is input from a bus bar breaker (1) that communicates the first and second buses. that busbar breaker status signal (S _CB) indicates the insertion of the mother line contact breakers, and, first and second busbar line switch to contact said first and second bus (2 _1, 2 ₂ ) only when the first and second bus connection line switch state signals (S _LS1 , S _LS2 ) input from 2 ₂ ) indicate that the first and second bus connection line switches are turned on A failure of the first and second instrument transformers may be detected.
One cycle of the first U-phase, V-phase, and W-phase peak-peak voltages (U _1p-p , V _1p-p , W _1p-p ) based on the first U-phase, V-phase, and W-phase instantaneous voltages And the second U-phase, V-phase, and W-phase peak peak voltages (U _2p-p , V _2p-p , W _2p-) based on the second U-phase, V-phase, and W-phase instantaneous voltages. _p ) is determined for each cycle, and the determined first and second U phase, V phase, and W phase peak-to-peak voltages are compared for each cycle to determine the first and second U phase, V phase And a peak-to-peak voltage detecting means (13) for storing the larger one of the W-phase peak-peak voltage as the U-phase, V-phase, and W-phase peak-peak voltages one cycle before.
Display means for causing the display device (20) to display the failure detection results of the first and second instrument transformers by the instrument transformer failure detection means and the failure phase determination results by the failure phase detection means. You may have.

The instrument transformer fault phase detector of the present invention has the following effects.
(1) A phase in which the value obtained by dividing the U-phase, V-phase, and W-phase instantaneous voltage differences by the U-phase, V-phase, and W-phase peak-to-peak voltages one cycle before becomes a predetermined value or more is determined as a failure phase, When both the divided values are smaller than the predetermined value, it is possible to quickly detect the failed phase of the first and second instrument transformers by determining the zero phase as the failed phase. .
(2) The reliability of the instrument transformer can be improved without duplication.
(3) Cost can be reduced as compared with duplexing.
(4) It becomes the standard for restrictions on equipment renewal (extension).

It is a figure which shows the structure of the instrument transformer fault phase detection apparatus 10 by one Example of this invention. 3 is a flowchart for explaining operations of a failure PD detection unit 14 and a failure phase detection unit 15 shown in FIG. 1. 3 is a flowchart for explaining operations of a failure PD detection unit 14 and a failure phase detection unit 15 shown in FIG. 1. 3 is a flowchart for explaining operations of a failure PD detection unit 14 and a failure phase detection unit 15 shown in FIG. 1. It is a figure for demonstrating the characteristic of the transformer fault phase detector for instruments of this invention.

  For the above purpose, when a failure of one of the first and second instrument transformers is detected, the U-phase, V-phase and W-phase instantaneous voltage differences are converted to the U-phase, V-phase and W-phase one cycle before. A phase in which the value divided by the peak-to-peak voltage is greater than or equal to a predetermined value is determined as a failure phase, and if all the divided values are smaller than the predetermined value, the zero phase is determined as a failure phase. .

Embodiments of an instrument transformer fault phase detection apparatus according to the present invention will be described below with reference to the drawings.
An instrument transformer fault phase detection device of the present invention includes a busbar connection breaker (busbar connection CB) 1 and first and second busbars for connecting a former bus and a second bus (which constitutes a double bus) shown in FIG. When all of the bus connection line switches (first and second bus connection LS) 2 ₁ , 2 ₂ are turned on, the first instrument transformer (first PD) 3 installed on the bus A ₁ U-phase, V-phase, W-phase and zero-phase instantaneous voltages U ₁ , V ₁ , W ₁ , Z ₁ (secondary output of the _first instrument transformer 3 ₁ ) output from ₁ and the Otobus The second U-phase, V-phase, W-phase and zero-phase instantaneous voltages U ₂ , V ₂ , W ₂ , Z ₂ output from the second instrument transformer (second PD) 3 ₂ installed in In view of the fact that (secondary output of the second instrument transformer 3 ₂ ) is substantially equal, either one of the first and second instrument transformers 3 ₁ , 3 ₂ is In the case of failure, the first and second U-phase, V-phase and W-phase instantaneous voltages U ₁ , V ₁ and W ₁ output from the first and second instrument transformers 3 ₁ and 3 ₂ , respectively. , U ₂ , V ₂ , W ₂ , which are absolute values of U, V and W phase instantaneous voltage differences ΔU (= | U ₁ −U ₂ |), ΔV (= | V ₁ −V ₂ |) , ΔW (= | W ₁ −W ₂ |), and the obtained U-phase, V-phase, and W-phase instantaneous voltage differences ΔU, ΔV, ΔW are converted into U-phase, V-phase, and W-phase peak peak voltage U _pp one cycle before. , V _pp , W _pp (first U-phase, V-phase and W-phase peak peak voltages U _1p-p , V _1p-p , W _1p output from the first instrument transformer 3 ₁ one cycle before) _-p and the second U-phase, V-phase, and W-phase peak-to-peak voltages U _2p-p , V _2p-p , W _2p-p output from the second instrument transformer 31 _one cycle before Divided by the larger one) Value _{(= ΔU / U pp, ΔV} / V pp, ΔW / W pp) phase becomes equal to or larger than a predetermined value (U-phase, V-phase or W-phase) determines that the failure phase, also in this divided value is either If it is smaller than the predetermined value, the zero phase is determined as a failure phase.

Therefore, an instrument transformer fault phase detection device 10 (hereinafter referred to as “fault phase detection device 10”) according to an embodiment of the present invention includes an input converter 11 and an analog input unit as shown in FIG. 12, a peak-peak voltage detector 13 (hereinafter referred to as “V _pp detector 13”), a failure instrument transformer detector 14 (hereinafter referred to as “failed PD detector 14”), a failure. A phase detection unit 15 and a display unit 16 are provided.

Here, the input converter 11 includes the first U-phase, V-phase, W-phase and zero-phase voltages input from the first instrument transformer 3 ₁ (see FIG. 5) installed on the bus A and the second converter. The second U-phase, V-phase, W-phase and zero-phase voltage levels input from the second instrument transformer 3 ₂ (see FIG. 5) installed on the bus are suitable for processing of the analog input unit 12. It is for converting to a level.

  The analog input unit 12 includes a band-pass filter, a sampling hold circuit, a multiplexer circuit, and an analog / digital converter, and the analog first U phase, V phase, W phase, and zero phase input from the input converter 11. The voltage and the second U-phase, V-phase, W-phase and zero-phase voltage are converted into the digital first U-phase, V-phase, W-phase and zero-phase voltage and the second U-phase, V-phase, W-phase and zero-phase voltage. It is for converting to voltage.

The V _pp detector 13 is based on the first U-phase, V-phase, and W-phase instantaneous voltages U ₁ , V ₁ , W ₁ input from the analog input unit 12, and the first U-phase, V-phase, and W-phase. The peak-peak voltages U _1p-p , V _1p-p , W _1p-p are obtained every cycle, and the second U-phase, V-phase and W-phase instantaneous voltages U ₂ , V input from the analog input unit 12 are obtained. ₂ and W ₂ , the second U-phase, V-phase and W-phase peak-peak voltages U _2p-p , V _2p-p , W _2p-p are determined for each cycle, and the determined first U-phase, V-phase and W-phase peak peak voltages U _1p-p , V _1p-p , W _1p-p and second U-phase, V-phase and W-phase peak peak voltages U _2p-p , V _2p-p , W _2p-p is compared for each cycle, and the larger of the two is stored as U-phase, V-phase, and W-phase peak-peak voltages U _pp , V _pp , W _pp one cycle before.

The fault PD detector 14 is connected to the busbar breaker status signal S _CB (a low level signal when the busbar breaker 1 is turned on) and the first and second busbar contacts inputted from the bus bar breaker 1. line switch 2 _1, 2 the first and second busbar line switch state signal S _{LS1 2} is input from, S _LS2 (the first and second busbar line switch 2 _1, 2 ₂ is turned When the signal level of the first U-phase, V-phase, and W-phase instantaneous voltages U ₁ , V ₁ , W ₁ input from the analog input unit 12 is all low, A value obtained by dividing the voltage by “3” (= (U ₁ + V ₁ + W ₁ ) / 3) and the first zero-phase instantaneous voltage Z ₁ input from the analog input unit 12 (first instrument transformer 3 ₁ Difference (= (U ₁ + V ₁ + W ₁ ) / 3−Z ₁ ) and the obtained difference There within a predetermined range (e.g., 0.1 v inclusive -0.1 V) when the not in conjunction with the determination "first voltage transformer 3 ₁ fails", is input from the analog input unit 12 The value obtained by dividing the vector sum of the second U-phase, V-phase and W-phase instantaneous voltages U ₂ , V ₂ and W ₂ by “3” (= (U ₂ + V ₂ + W ₂ ) / 3) and analog input The difference (= (U ₂ + V ₂ + W ₂ ) / 3−Z ₂ ) from the second zero-phase instantaneous voltage Z ₂ (the tertiary output of the _first instrument transformer 3 ₁ ) input from the unit 12 is obtained. , within the obtained difference is in a predetermined (e.g., 0.1 v inclusive -0.1 V) when the not in determining the "second instrument transformer 3 ₂ fails".

The failure phase detection unit 15 indicates that the failure PD determination result signal input from the failure PD detection unit 14 indicates that “one of the first and second instrument transformers 3 ₁ and 3 ₂ has failed”. In the case shown, the U phase, V phase, and W phase peak peak voltages U _pp , V _pp , W _pp stored in the V _pp detector 13 are read out and inputted from the analog input unit 12. The absolute values of the differences between the first and second U-phase, V-phase and W-phase instantaneous voltages U ₁ , V ₁ , W ₁ , U ₂ , V ₂ and W ₂ are taken to obtain the U-phase, V-phase and W-phase. The instantaneous voltage differences ΔU, ΔV, ΔW are obtained, and the obtained U-phase, V-phase and W-phase instantaneous voltage differences ΔU, ΔV, ΔW are converted into U-phase, V-phase and W-phase peak peak voltages U _pp , V _pp , W _pp respectively divided by the _{(= ΔU / U pp, ΔV} / V pp, ΔW / W pp) a predetermined value (e.g., 0. ) The above since the phase is determined that failure phase, when this divided value is less than the predetermined value either is determined that the failure phase zero-phase.

  Based on the failure PD detection result signal input from the failure PD detection unit 14 and the failure phase determination result signal input from the failure phase detection unit 15, the display unit 16 detects the detection result and failure phase detection in the failure PD detection unit 14. The determination result in the unit 15 is displayed on the display device 20.

Next, operations of the failure PD detection unit 14 and the failure phase detection unit 15 will be described with reference to the flowcharts shown in FIGS.
The fault PD detection unit 14 monitors the levels of the bus connection breaker status signal S _CB and the first and second bus connection line switch status signals S _LS1 and S _LS2 (step S11), and the bus connection breaker status signal. When S _CB and first and second bus connection line switch state signals S _LS1 , S _LS2 are all at low level (S _CB , S _LS1 , S _LS2 = L), the first U phase, V phase and The difference between the value obtained by dividing the vector sum of the W-phase instantaneous voltages U ₁ , V ₁ , W ₁ by “3” and the first zero-phase instantaneous voltage Z ₁ (hereinafter referred to as “first difference Δ ₁ ”) Δ ₁ = (U ₁ + V ₁ + W ₁ ) / 3−Z ₁ ) and the voltage of the vector sum of the second U-phase, V-phase and W-phase instantaneous voltages U ₂ , V ₂ and W ₂ is “3”. the difference between the value and the second zero-phase instantaneous voltage Z ₂ divided by _{(hereinafter, .Δ 2 = (U 2 +} V 2 + W 2 referred to as "second difference delta _2") / 3-Z ₂₎ determined the First and second differential delta ₁ was determined, delta ₂ is in a range of 0.1v or _{-0.1v (-0.1v ≦ Δ 1, Δ} 2 ≦ 0.1v) whether the Check (step S12).

Determination result, failure PD detection unit 14, when only the first difference delta ₁ is not within the range of 0.1v above -0.1 V, the "first voltage transformer 3 ₁ fails" (Step S13).
If only the second difference Δ ₂ is not in the range of not less than −0.1 v and not more than 0.1 v, the failure PD detection unit 14 determines that “the second instrument transformer 3 ₂ has failed” (Step S1). S14).
If the first and second differences Δ ₁ and Δ ₂ are not in the range of not less than −0.1 v and not more than 0.1 v, the failure PD detection unit 14 indicates that “the first and second instrument transformers 3 ₁ , 3 ₂ have both failed ", a failure PD detection result signal indicating that is output to the display unit 16, and this is displayed on the display device 20 (step S15).

Failure PD detection unit 14 determines that the "first voltage transformer 3 ₁ fails" in step S13, and outputs a fault PD detection result signal indicating that the failure phase detection unit 15 and the display unit 16 .

The failure phase detection unit 15 that has received this failure PD detection result signal reads the U-phase, V-phase, and W-phase peak peak voltages U _pp , V _pp , and W _pp one cycle before from the V _pp detection unit 13, and first The absolute value of the difference between the U-phase, V-phase and W-phase instantaneous voltages U ₁ , V ₁ and W ₁ and the second U-phase, V-phase and W-phase instantaneous voltages U ₂ , V ₂ and W ₂ U phase, V phase, and W phase instantaneous voltage differences ΔU, ΔV, ΔW are obtained, and the U phase, V phase, and W phase instantaneous voltage differences ΔU, ΔV, ΔW are determined as one cycle before the U phase, V phase, and W phase peaks. It is checked whether the values divided by the peak voltages U _pp , V _pp , and W _pp are 0.1 or more.

As a result, only the value obtained by dividing the U-phase instantaneous voltage difference ΔU by the U-phase peak peak voltage U _pp one cycle before is 0.1 or more (ΔU / U _pp ≧ 0.1 and ΔV / V _pp , ΔW / W _pp <0.1), the failure phase detection unit 15 determines that the U phase of the _first instrument transformer 31 has failed, and displays a failure phase determination result signal indicating that fact. It outputs to the part 16 and displays that on the display apparatus 20 (step S21, S22 of FIG. 3).
Only the value obtained by dividing the V-phase instantaneous voltage difference ΔV by the V-phase peak-peak voltage V _pp one cycle before is 0.1 or more (ΔV / V _pp ≧ 0.1, and ΔU / U _pp , ΔW / W _pp <0.1), the failure phase detection unit 15 determines that “the V phase of the _first instrument transformer 31 has failed”, and displays a failure phase determination result signal indicating that fact on the display unit 16. The information is output and displayed on the display device 20 (steps S23 and S24).
Only the value obtained by dividing the W phase instantaneous voltage difference ΔW by the W phase peak peak voltage W _pp one cycle before is 0.1 or more (ΔW / W _pp ≧ 0.1, and ΔV / V _pp , ΔU / U _pp <0.1), the failure phase detection unit 15 determines that the W phase of the _first instrument transformer 31 has failed, and displays a failure phase determination result signal indicating that fact on the display unit 16. The information is output and displayed on the display device 20 (steps S25 and S26).
All values obtained by dividing the U-phase, V-phase, and W-phase instantaneous voltage differences ΔU, ΔV, ΔW by the U-phase, V-phase, and W-phase peak-peak voltages U _pp , V _pp , W _pp one cycle before are all 0.1 or more If not (ΔU / U _pp , ΔV / V _pp , ΔW / W _pp <0.1), the failure phase detector 15 determines that “the zero phase of the _first instrument transformer 31 has failed”. Then, a failure phase determination result signal indicating that fact is output to the display unit 16 and the fact is displayed on the display device 20 (steps S27 and S28).

Similarly, the failure PD detection unit 14 determines that the "second instrument transformer 3 ₂ fails" in step S13, the failure phase detecting unit 15 and a display unit 16 failure PD detection result signal indicating Output to.

The failure phase detection unit 15 that has received this failure PD detection result signal reads the U-phase, V-phase, and W-phase peak peak voltages U _pp , V _pp , and W _pp one cycle before from the V _pp detection unit 13, and first The absolute value of the difference between the U-phase, V-phase and W-phase instantaneous voltages U ₁ , V ₁ and W ₁ and the second U-phase, V-phase and W-phase instantaneous voltages U ₂ , V ₂ and W ₂ U phase, V phase, and W phase instantaneous voltage differences ΔU, ΔV, ΔW are obtained, and the U phase, V phase, and W phase instantaneous voltage differences ΔU, ΔV, ΔW are determined as one cycle before the U phase, V phase, and W phase peaks. It is checked whether the values divided by the peak voltages U _pp , V _pp , and W _pp are 0.1 or more.

As a result, only the value obtained by dividing the U-phase instantaneous voltage difference ΔU by the U-phase peak peak voltage U _pp one cycle before is 0.1 or more (ΔU / U _pp ≧ 0.1 and ΔV / V _pp , ΔW / W _pp <0.1), the failure phase detector 15 determines that “the U phase of the _second instrument transformer 32 has failed” and displays a failure phase determination result signal indicating that fact. It outputs to the part 16 and displays that on the display apparatus 20 (step S31, S32 of FIG. 4).
Only the value obtained by dividing the V-phase instantaneous voltage difference ΔV by the V-phase peak-peak voltage V _pp one cycle before is 0.1 or more (ΔV / V _pp ≧ 0.1, and ΔU / U _pp , ΔW / W _pp <0.1), the failure phase detection unit 15 determines that “the V phase of the _second instrument transformer 32 has failed”, and displays a failure phase determination result signal indicating that fact on the display unit 16. The information is output and displayed on the display device 20 (steps S33 and S34).
Only the value obtained by dividing the W phase instantaneous voltage difference ΔW by the W phase peak peak voltage W _pp one cycle before is 0.1 or more (ΔW / W _pp ≧ 0.1, and ΔV / V _pp , ΔU / U _pp <0.1), the failure phase detection unit 15 determines that “the W phase of the _second instrument transformer 32 has failed”, and displays a failure phase determination result signal indicating the fact on the display unit 16. The information is output and displayed on the display device 20 (steps S35 and S36).
All values obtained by dividing the U-phase, V-phase, and W-phase instantaneous voltage differences ΔU, ΔV, ΔW by the U-phase, V-phase, and W-phase peak-peak voltages U _pp , V _pp , W _pp one cycle before are all 0.1 or more If not (ΔU / U _pp , ΔV / V _pp , ΔW / W _pp <0.1), the failure phase detector 15 determines that “the zero phase of the _second instrument transformer 32 has failed”. Then, a failure phase determination result signal indicating that fact is output to the display unit 16 and the fact is displayed on the display device 20 (steps S37 and S38).

In the above description, the fault phase detection device 10 is one phase of either one of the first and second instrument transformers 3 ₁ and 3 ₂ installed on the former bus and the second bus constituting the double bus. Although the failure phase at the time of failure is detected, the following applications are also possible.
(1) In the case of a 2CB system with a 6.6 kV bus, the first and second subordinate secondary circuit breakers are provided on condition that both the first and second subordinate secondary circuit breakers are turned on. A failure phase is detected when one of the first and second grounding transformers (GPT) installed in the first and second buses connected to each other fails.
(2) In the 6.6 kV or 22 kV power system, when the first and second buses are connected via a bus bar breaker, the first and A failure phase is detected when one phase of either one of the first and second grounding transformers respectively installed on the second bus bar fails.

DESCRIPTION OF SYMBOLS 1 Bus line breaker 2 ₁ , 2 ₂ 1st and 2nd bus line connection line switch 3 ₁ , 3 ₂ 1st and 2nd instrument transformer 10 Fault phase detector 11 Input converter 12 Analog input part 13 V _pp voltage detection unit 14 Fault PD detection unit 15 Fault phase detection unit 16 Display unit 20 Display devices U ₁ , V ₁ , W ₁ , Z ₁ First U phase, V phase, W phase and zero phase instantaneous voltage U ₂ , V ₂ , W ₂ , Z ₂ Second U phase, V phase, W phase and zero phase instantaneous voltage U _pp , V _pp , W _pp 1 cycle before U phase, V phase and W phase peak peak voltage U _{1p− p} , V _1p-p , W _1p-p first U phase, V phase and W phase peak peak voltage U _2p-p , V _2p-p , W _2p-p second U phase, V phase and W phase Peak peak voltage S _CB bus bar breaker status signal S _LS1 , S _LS2 first and second bus bar line switch state signal ΔU, ΔV, ΔW U phase, V phase and W phase instantaneous voltage difference Δ ₁ , Δ ₂ first and second difference

Claims (4)

For an instrument for detecting a failure phase when one of the first and second instrument transformers (3 ₁ , 3 ₂ ) installed on the first and second buses, respectively, fails A transformer fault phase detector (10), comprising:
First U-phase, V-phase and W-phase instantaneous voltages (U ₁ , V ₁ , W ₁ ) output from the first instrument transformer and a first output from the first instrument transformer. And the second U-phase, V-phase and W output from the second instrument transformer, while detecting a failure of the first instrument transformer based on the zero-phase instantaneous voltage (Z ₁ ) Based on the phase instantaneous voltage (U ₂ , V ₂ , W ₂ ) and the second zero-phase instantaneous voltage (Z ₂ ) output from the second instrument transformer, the second instrument transformer Instrument transformer fault detection means (14) for detecting faults;
When the failure of one of the first and second instrument transformers is detected by the instrument transformer failure detection means, the first and second U-phase, V-phase and W-phase instantaneous voltages are detected. The absolute value of the difference is taken to determine the U-phase, V-phase, and W-phase instantaneous voltage differences (ΔU, ΔV, ΔW), and the U-phase, V-phase, and W-phase instantaneous voltage differences obtained are The phase in which the value divided by the phase and the W-phase peak peak voltage (U _pp , V _pp , W _pp ) is greater than or equal to a predetermined value is determined as a failure phase, and both the divided values are higher than the predetermined value. A failure phase detection means (15) for determining that the zero phase is a failure phase if small,
An instrument transformer fault phase detection device comprising: The first and second buses constitute a double bus;
The instrument transformer failure detection means is connected to the busbar breaker state signal (S _CB ) input from the busbar breaker (1) that connects the first and second busbars. And the first and second bus connection line switch states inputted from the first and second bus connection line switches (2 ₁ , 2 ₂ ) communicating the first and second buses A failure of the first and second instrument transformers is detected only when a signal (S _LS1 , S _LS2 ) indicates the input of the first and second busbar connection line switches;
The instrument transformer fault phase detection device according to claim 1, wherein: One cycle of the first U-phase, V-phase, and W-phase peak-peak voltages (U _1p-p , V _1p-p , W _1p-p ) based on the first U-phase, V-phase, and W-phase instantaneous voltages And the second U-phase, V-phase, and W-phase peak peak voltages (U _2p-p , V _2p-p , W _2p-) based on the second U-phase, V-phase, and W-phase instantaneous voltages. _p ) is determined for each cycle, and the determined first and second U phase, V phase, and W phase peak-to-peak voltages are compared for each cycle to determine the first and second U phase, V phase And a peak-to-peak voltage detecting means (13) for storing the larger one of the W-phase peak-to-peak voltage as the U-phase, V-phase, and W-phase peak-to-peak voltages one cycle before the cycle. Item 3. The instrument transformer fault phase detector according to Item 1 or 2.   Display means for causing the display device (20) to display the failure detection results of the first and second instrument transformers by the instrument transformer failure detection means and the failure phase determination results by the failure phase detection means. The instrument transformer phase detector according to any one of claims 1 to 3, further comprising:

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