JPS61142922A - Disconnection detector/relay - 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] Total usage during separation from work The present invention relates to a disconnection detection relay for power transmission lines.

Conventional technology: In the event of a disconnection accident in a power transmission line, the circuit is interrupted by a protective relay that is accompanied by a short circuit or ground fault, but when the subsequent disconnection occurs and the power is retransmitted without being grounded, the existing maintenance relay is used. Unable to detect, power is transmitted in open phase condition, **
It may cause a lot of trouble at home.

Problems to be Solved by the Invention Conventionally, there has been no practical, effective, and low-cost detection method for the above-mentioned problems, and there is no practical type of connector that reliably protects against 1ilT line accidents. Especially in the present invention, 1s of power transmission line! The object of the present invention is to enable reliable and easy detection of wire breakage even when there is no ground fault or short circuit.

Means for Solving the Problems The present invention disconnects the phase when the current of any one phase is less than the average current of the three phases and continues for more than a predetermined time. The reason is that it is configured to be detected as .

Example The present invention will be described in detail below with reference to the drawings.

#! Figure 1 shows that only one phase of the three-phase current is smaller than the average current of the three phases and continues for a predetermined time. This is a block diagram shown in the example. In the figure, the detection current xR-XB・IT of each phase of the power transmission line is the rectifier IR,
, rectified and smoothed by IT and converted to DC level. The average value detection circuit 2 outputs the average value of each output from the rectifiers IR, 1s, and I. The place name setting circuit 3 has a function of variably setting the Kitamoto signal set for the output of the average value detection circuit 2 according to the configuration of the protected system. The level detector 4 compares the set value of the minimum sensitivity setter 5 and the detected output of the average value detection circuit 2 at t level to detect whether the detected output is less than the set value. Comparator 6R/6B/6T
compares the t level with the output of the rectifier IR.1s.IT and the output of the place name setting circuit 3, and detects for each phase that it has fallen below the Higa setting. Comparison 6R* fi6, 6p
It includes means for permitting a comparison operation using the detection output of the tl level detector 4. The suppression circuits 7R, 7th, and 7T output the detection outputs of the corresponding comparators 6R, 6B, and 6T to other comparators 8B and 6T.
, 6T and 6R, and 6R and 6s detection outputs, it is enabled when comparison output is obtained for only one phase, and disabled when output is obtained for two or more phases. Has a function.

Display 8R, 86, 8Tt! Each suppression circuit 7R-78-7
It lights up when the valid output of T occurs, and the corresponding phase is turned off. Inhibition circuit 7R via timer circuit 10Ifi OR gate 9
- Input the valid output of 7 days and 7T, and detect that the input continues for a certain period of time. The power amplifier 11 amplifies the detected output of the timer circuit 10 and displays the disconnection occurrence indicator 1 of the line.
2. Turn on all lights and drive the relevant line cutoff command relay @13t.

With the above configuration, the average current of the three-phase currents IR, zB, and IT is detected by the average value detection circuit 2, and a current of a predetermined ratio I of the average current is detected by the place name setting circuit 3. luxury n
, it is detected by the comparators 6R, 68, and 6T that the phase currents IH, IB, and IT are below the predetermined Union current.
The timer circuit 1 determines that the phase detected by this comparator is limited to one phase by the suppression circuits 7R, 7, and 7T, and that the current drop in the phase has continued for a certain period of time or more.
Detected by 0 n.

The occurrence of ilTm in the circuit is displayed on the display 12, and the circuit is cut off by the relay 13.

When the current of two phases among the three phase currents decreases below a predetermined ratio compared to the average current, the outputs of the comparators 6R, 6B, and 6 become zero, locking the related edge detection operation. . Since measures can be taken appropriately in the event of a breakage accident in the friend l phase, it is possible to minimize the negative IP impact on customers.

FIG. 2 is a block diagram showing an example of application of the first embodiment to a line power receiving system. In a system where power is being transmitted from the power supply 21 to the load 22 in a balanced manner using No. 91 No. i 23 and No. 2 Odd No. 24, if the L phase is disconnected in the R phase of No. 1 Odd No. 23, 5
The currents IEI and IT of the 8-phase and T-phase in 23.24 hardly change, but the R-phase current of the 1-square wire 23 is zero, and the R-phase current of the 2-odd edge 24 is about twice the current before the disconnection. Become. Stop here #l
[Streamline electric appliances 25° and 26 are provided in 19 wires 23 and 2 [24, respectively, and the setting amount α of Kitamoto setting circuit 3 = I/I
Even if it is set to m, aD20, 9, the I R of No. 1 + W23
/Ime,, n = 0, and the disconnection current relay 25
operates and displays R phase wire breakage. In addition, disconnection current relay 2
6, Is/Imean*IT/Imean are both about 0.75, and the S-phase and T-phase currents are below the set value, so the relay 26 becomes inoperable, and the relay 26 of line 1
Can detect wire breaks.

FIG. 3 shows an example of the application of the first embodiment in a system with a large branch load. Power is transmitted from the power source 21 to the load 22 via the 1-square wire 23°2 odd edge 24, and the 1-square wire 23 and No. 2 N24
In a branch load system in which power is branched to each load 27 and transmitted to the load 27, disconnection detection relays 28m 29 +30e317 are installed on the power transmission lines to the respective loads 22゜2). In this case, if the load 27 becomes larger than the load 22 and the disconnection point of No. 1 l1ij 23 is closer to the load 22 than the load 270 branch point, a large change will appear in the current at the transmission end. do not have. Ninth, if a disconnection detection relay is placed at the power transmission end, disconnection a cannot be detected. Therefore, in this embodiment, relays 28 to 31i are provided at the ends of the receiver 1 to detect single wire breaks*1 at all locations.

In addition to branch systems such as the one on the left, broken lines and phases can be reliably detected by setting the relay installation point and place name setting values to appropriate values, although this may occur in the case of a rough branch.

FIG. 4 shows a second embodiment, and this second embodiment has three
It is a block diagram in the case where any phase current among the phase currents is less than a predetermined ratio compared to the average current of three phase currents and continues for a predetermined time. As is clear from the comparison between FIG. 4 and FIG. 1, the second embodiment is not provided with the suppression circuits 7R and 78°7T of the first embodiment shown in FIG. That is, comparator aFt.

68.6T output to other comparators 68 and 6T, 6T and 6R
.

The outputs of the comparators 46R, 468, and 4BT are input directly to the OR gate 9 without installing a circuit that suppresses them with the outputs of 6R and 68 and disables them when a comparison output is obtained for two or more phases. In this respect, the structure is different from the first embodiment.

From this configuration, the disconnection detection relay of the second embodiment detects that phase when the current of any phase is less than a predetermined value X compared to the average current of the three phase currents and continues for a predetermined time or longer. It is determined that the phase is interrupted, and if the average current becomes less than a predetermined 'It current, one operation is locked.

When this second embodiment is applied to a two-line power receiving system as shown in FIG. 2 as in the first embodiment, the 8-phase and T-phase currents hardly change or The R-phase current of the line is zero, and the R-phase current of the two-band line is about twice the current before the disconnection. If the specific suspension setting α”X/r mean” is set to o, s, then
It became XR/Imflan on line 1.

The disconnection current line 1 of line 1 is operated and the R phase is displayed, but 18/rmean e IT' and esan are both approximately 0.75, and each phase is inoperable and line 2 is disconnected IWt.
Current relay becomes inoperable. That is, there is an effect that a disconnected line can be selected by appropriately selecting the blockage setting.

Also, the third embodiment can be applied to systems with large branch loads and complex branch circuits in the same way as the first embodiment.

Effect of the invention From the above explanation, the present invention has the following effects.

il+ Since a disconnection is determined based on the ratio of the average current in each line to each phase current, a disconnection phase can be reliably detected regardless of the size of the load.

;2) Since the Kitamoto setting value is variable, the present invention can be applied to almost any single power system by selecting the installation point of the device of the present invention and the Kitamoto setting value.

(3: Transmission 1! When a transformer in a line system is turned on, an unbalanced current similar to a disconnection occurs in the transmission line for a long time.The ninth aspect of the present invention is to prevent erroneous detection due to this unbalanced current. However, in order to avoid the delay in disconnection detection due to the timer setting time, when the average current of the three-phase current decreases below the normally considered load current, By locking the Kitamoto detection of the ratio setting circuit, the setting time of the timer circuit can be shortened and the disconnection detection can be performed reliably and quickly.

(4) Disconnection detection 'k I 'Imax *Max is I/l
Since the test is performed by comparing 1nean, there is no need to prepare a three-phase balanced power supply, and the test can be performed with a single-phase power supply. Therefore, on-site testing is easy.

15: Since the configuration is a combination of a small number of circuit elements, it is small, low cost, and can reliably detect open phase and open circuit SL.

(6) Applicable to any number of two-line power receiving systems and single-line power receiving systems.

[Brief explanation of the drawing]

Figure 1 or #! 3 is related to the first embodiment of the present invention, FIG. 1 is a block diagram of a disconnection detection relay, and FIG. 2 is a block diagram of a disconnection detection relay.
FIG. 3 is a block diagram showing the application of the first embodiment to an i2 line power receiving system, FIG. 3 is a block diagram showing the application of the first embodiment to a system with branched loads, and FIG. 4 is a second embodiment of the present invention. FIG. 2 is a block diagram of a disconnection detection relay. IR・1B-1... Rectifier, 2... Average value detection circuit, 3.42... Kitamoto setting circuit, 4.44... Level detector, 5.45... Minimum sensitivity footer , 6B・6s・
6T. 46R/46s/46T... Comparator, 7R-78-7
T... Inhibition circuit, 8R/8s/8T... Display, 9
...OR gate, lO...timer, 12...cut g
Occurrence indicator, 13... Cutoff command relay.

Claims (2)

[Claims] (1) Only one phase current among the three phase currents is less than a predetermined ratio compared to the average current of the three phase currents and continues for a predetermined time or more,
A disconnection detection relay characterized in that a disconnection detection relay is configured to determine a phase disconnection and a line disconnection of the one-phase current on the condition that the average current of the three-phase current is equal to or higher than a predetermined value. (2) Any one of the three-phase currents is less than a predetermined ratio compared to the average current of the three-phase currents and continues for a predetermined time or more, and the average current of the three-phase currents is greater than or equal to the predetermined value. A disconnection detection relay characterized in that it is configured to determine a phase disconnection and a line disconnection in any of the phase currents under the conditions.