JPS61248332A - Fuse out detector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a blown fuse detection device, particularly to a blown fuse detection device on the secondary side of a voltage transformer of a power transmission line drawn out from a busbar system.

[Conventional technology]

Fig. 2 is a block diagram showing a protective relay system for a nine-system bus to which a conventional fuse blown detection device is applied.
c'rB and c'rc are current transformers installed in each phase of transmission lines A, B, and C, and FA g FB+ FC is a voltage transformer whose primary side is connected to each phase of power transmission 1jA, B, and C. Secondary-side detected fuses (hereinafter abbreviated as fuses) of PTA, PTB, and PTc and CB are circuit breakers provided on power transmission lines A, B, and C.

1 is a fuse blown detection device, 3-phase voltage va t b
A synthetic transformer TA v ``B + 'rc for deriving the zero-sequence voltage vo by inputting 1vc, and a zero-sequence voltage for detecting whether the zero-sequence voltage vo is equal to or higher than a predetermined value (for example, 104 of the rated voltage) The outputs of the detection element OVG, the zero-sequence current detection element OCG that detects whether the zero-sequence current 10 is equal to or higher than a predetermined value (for example, 1096 of the rated current), and the zero-sequence voltage detection element OVG are set as positive inputs, and the zero-sequence current is detected. Inhibit (INHIBIT) circuit IN that uses the output of the detection element OCG as an inhibit input
~1.

DZ is a protective distance relay for power transmission +pA, B, and C, and when a failure occurs in the power transmission line, it outputs a trip command to breaker CB. Also, power transmission! sA, B, C
With load current flowing through the voltage transformer p'rA.

”B HPTC secondary side fuse FA + FB r
When at least one of the FCs melts, it is assumed that a failure has occurred in the power transmission line, and the distance relay DZ makes an unnecessary response and outputs a trip command to the circuit breaker CB.

Therefore, in order to prevent unnecessary response of the distance relay DZ as described above, when the fuse blown detection device 1 is activated, it is connected so as to issue an alarm to the outside and automatically lock the distance relay DZ.

Next, the operation of the fuse blown detection device will be explained.

When the two fuses yFB+Fc are all normal, the three-phase voltage vaIvbνvc on the output side of the fuse is balanced at the healthy rated voltage, and the zero-phase voltage Vo is zero.

For example, voltage transformers p'rA, PTB, p'rc
When a short-circuit failure occurs in the A-phase and B-phase on the secondary side, the fuse FAyFB is blown, so a zero-sequence voltage Vo is generated, and the zero-sequence voltage detection element OVG is activated. On the other hand, since no ground fault has occurred on grid transmission lines A, B, and C,
The zero-sequence current 10 is zero, and the zero-sequence current detection element OCG is inactive. Therefore, the inhibit circuit lN-1 outputs an output for detecting a blown fuse.

Also, it's not the fuse that's blown, it's the grid transmission line A.

Even if a one-phase ground fault occurs in B and C, the zero-sequence voltage detection element OVG operates, but at this time, the zero-sequence current 1. occurs, and the zero-sequence current detection element OCG also operates, so that the inhibit circuit IN-1 does not generate an output for fuse blown detection.

[Problem that the invention seeks to solve]

Since the conventional fuse blown detection device is configured as described above, one of the fuses FA + FB r FC
If a phase or two-phase fuse is blown, the zero-sequence voltage V
Q is generated to detect a blown fuse, but if all three phase fuses are blown, there is a problem in that zero-sequence voltage Vo is not generated and cannot be detected.

This invention was made in order to solve the above-mentioned problems, and it is a highly sophisticated technology that can reliably detect a fuse blown not only in one phase or two phases but also in the case where all three phases are blown. The purpose is to obtain a sensitive fuse blown detection device.

[Means for solving problems]

The blown fuse detection device according to the present invention includes a three-phase high setting undervoltage detection element connected to the secondary side of a voltage transformer of a system bus, and a voltage transformer secondary side of a transmission ms drawn out from the system bus. A logic circuit is provided that detects a fuse blowout based on the operating conditions of a three-phase low-settling undervoltage detection element connected to the output side of the fuse.

[Effect]

The logic circuit of the fuse blown detection device in this invention is comprised of 3
A fuse blown detection is output on the condition that all the phase high-settling undervoltage detection elements are inoperative and any of the three-phase low-settling undervoltage detection elements for one phase is in operation.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In the first factor, Ao, Bo, Cc+ are the systematic bus lines, PT
A 01 PT BO + PTCo is a voltage transformer whose primary side is connected to the system bus, FAo, FBo, Fco are fuses installed on the secondary side of voltage transformers PTAo, PTBO, PTcO, Al * "1 r C1 is the first transmission gauze drawn out from the grid bus, 01 person 1 + c'
rBl l CTe1 is the first power transmission line AL IBl, C1
Current transformer installed in PTA l t P T B l
r PTC1 is a voltage transformer whose primary side is connected to the first transmission line, F Al rFBl+FC1 is a voltage transformer PTA
l r PTBl + Detected fuse installed on the secondary side of PTCI, CBAI r CB Bl + CBC
I is the breaker of the first power transmission line AI r Bl r C1,
DZ-1 is a distance relay for the first feed line Al s Bl + C1, and 11 is a fuse blown detection device.

The fuse blown detection device 11 is a three-phase high setting undervoltage detection element HA r installed on the secondary side of the voltage transformer of the bus bar.
HB, HC, an OR circuit 0R-0 whose input is the output of this high-setting undervoltage detection element, and the detected fuse FA.
Low setting undervoltage detection element installed on the output side of FCl LAl y "11 + LCI
and O with the output of this low-setting undervoltage detection element as input.
It is composed of an R circuit 0R-1 and an inhibit circuit 1N-1 which uses the output of the OR circuit OR-0 as an inhibit input and the output of the OR circuit 0R-1 as a forward input.

The above high setting undervoltage detection element HA, )TB + H
The detection sensitivity of C is set to about 0.8 times the rated voltage so as not to react to regular healthy voltage fluctuations, and the detection sensitivity of the low setting undervoltage detection element IjAl * "Bl +" C1 is set to 0.0 times the rated voltage. .Set it to about 7 times. The purpose of providing such a sensitivity difference is to ensure that when a failure occurs in the system and the L element operates, the H element can operate quickly and reliably.

Next, the operation of the fuse blown detection device according to the present invention will be explained. The system is healthy and the detected fuse FAI *
When FB1 +FC1 is normal, the high setting undervoltage detection element HA * HB eHc on the busbar and the low setting undervoltage detection element L A installed on the output side of the detected fuse
I HLB 1 + "Cl are all inactive, and no fuse blown detection output is generated from the inhibit circuit IN-1.

If a two-phase fuse blown of the detected fuses FAI and FBI occurs, the low setting undervoltage detection element LA 1 +
LB1 operates and an output is generated in OR circuit 0R-1.

On the other hand, high setting undervoltage detection element HA y HB + of the bus bar
All HCs are inactive and output is generated in OR circuit 0R-n ÷
stomach. Therefore, when fuse blowing occurs in all three phases of the detected fuses FAl+FBl+-FC1 after the fuse blown detection output is generated from the inhibit circuit IN-1, the low-settling undervoltage detection element LA ly y LB 1 + LC1 is activated. However, since the high-settling undervoltage detection element HA + HB + HC is inoperative, an output of fuse blown detection is generated from the inhibit circuit IN-1.

Not a blown fuse, but the first power transmission! lAl1B1. C.I.
When a ground fault or short circuit fault occurs in the K system, high-setting undervoltage detection elements HA + HB + HC operate in 1 phase or 3 phases depending on the fault condition, and inhibit circuit 1N-1 through OR circuit 0R-0. Since the inhibit input is applied to the low-settling undervoltage detection elements LA1 and LB1+Lc1, they also operate, but no fuse blown detection output is generated from the inhibit circuit IN-1.

In addition, in the above description, the voltage transformer p'rAl l p'rBl + p'rc of the first transmission current AI+Bi+C1
Tested 1fj fuse FAl t FB on the secondary side of 1
Although we have explained the case of detecting a break in the FCI, the high setting undervoltage detection element HA + HB r installed on the busbar can also be used to detect a break in the adjacent power transmission line.
Fuse blown detection can be performed simply by using the output of the HC and adding a low-settling undervoltage detection element to the power transmission line.

〔Effect of the invention〕

As described above, according to the present invention, three
All of the phase high setting undervoltage detection elements are inoperative, and 3 of the output side of the detected fuse of the transmission line drawn from the above system bus.
Since the configuration is configured to detect a fuse blown under the condition that any one of the phase low-settling undervoltage detection elements is activated, 1
This has the effect of providing a highly reliable and highly sensitive fuse rupture detection device that can detect not only the fuse rupture of phase and two phases but also the fuse rupture of all three phases.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a blown fuse detection device according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional blown fuse detection device. HA + HB) TIC is a 3-phase high-settling undervoltage detection element, LAI・"B1+"CI is a 3-phase low-settling undervoltage detection element, lN-1 is a logic circuit (inhibit circuit)
. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A three-phase high-setting undervoltage detection element connected to the secondary side of the voltage transformer of the grid bus, and connected to the output side of the detected fuse on the secondary side of the voltage transformer of the transmission line drawn out from the grid bus. Under the condition that all of the three-phase low-settling undervoltage detection elements and the three-phase high-settling undervoltage detection elements above are inoperative, and one of the three-phase low-settling undervoltage detection elements is activated. A fuse rupture detection device comprising: a logic circuit for detecting fuse rupture of the fuse to be detected;