JPS6117215B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inspection circuit for inspecting the operation of a bus protection relay in a power system.

Conventionally, there has been an inspection circuit as shown in FIG. 1 as this type of inspection circuit. In FIG. 1, lines 2-1 and 2-2 are connected to bus 1 of the power system to be protected. AC generators 3-1 and 3-2 are connected to each line 2-1 and 2-2, respectively, to detect current. The secondary current of current transformers 3-1 and 3-2 is
are supplied to input devices 4-1 and 4-2, respectively,
After being level-converted, it is supplied to the bus protection relay 5 that detects a failure on the bus 1 via the line 3b, which is a common signal line, and after being converted to a DC level signal, via the line 3a, which is a common signal line. be done.

On the other hand, a check circuit 6 is provided to test the function of the busbar protection relay 5. Inspection circuit 6
converts the current of the power supply 7 for inspection into a DC signal by the converter 8, and supplies this to the bus protection relay 5 as a DC signal for inspection via the switch 9 and the wire 3a, and also converts the current of the power supply 7 to The level of the signal is converted by the transformer 10 to provide an AC signal for inspection, and the signal is supplied to the bus protection relay 5 via the switch 11 and the line 3b.

In the case of an internal failure in the bus 1, the bus protection relay 5 operates because DC and AC signals having voltages that are proportional to the current flowing at the time of the failure occur in the lines 3a and 3b. Further, in the case of an external failure of the bus 1, a DC signal is generated on the line 3a, but the value of the DC signal on the line 3b becomes zero, and the bus protection relay 5 does not operate. When inspecting the bus protection relay 5, the switches 9 and 11 are closed and a DC signal and a current transformation signal for inspection are supplied to the lines 3a and 3b, respectively.

With this configuration, individual failures of the input devices 4-1 and 4-2, such as disconnection of the transformer 13 or 14, cannot be detected.

The present invention has been made in order to eliminate the drawbacks of such conventional circuits, and it is an object of the present invention to provide an inspection circuit that can accurately detect failures in input devices and busbar protection relays.

The inspection circuit of the present invention includes a plurality of input devices provided for each of a plurality of lines connected to a bus bar, and a first and a second input device for converting the level of a secondary current of a current transformer provided in the line. the input device comprising a transformer and a rectifier connected to the secondary winding of the first transformer to obtain a DC signal; a first common signal line for guiding the DC signal of each of the input devices; In an inspection circuit for inspecting a bus protection circuit, the circuit includes a bus protection relay connected to a second common signal line that guides an alternating current signal output from a secondary winding of a second transformer to detect a failure of the bus. , a plurality of input devices having first and second transformers with tertiary windings, and a test provided to the second transformer by connecting the tertiary windings of the first and second transformers. and a switch for supplying an AC signal to the first transformer.

Hereinafter, an embodiment of the present invention will be specifically explained with reference to FIG. 2. In FIG. 2, the same reference numerals are used for the same parts as in FIG. 1, and repetitive explanations will be omitted. The secondary current of current transformer 3-1 is supplied to input device 15-1. Input device 15-1
has a pair of transformers 16 and 17, which have a primary winding p, a secondary winding s and a tertiary winding t. The connection circuit for the secondary winding s is similar to the conventional circuit. The tertiary windings t of transformers 16 and 17 are connected via a switch 18. When the switch 18 is closed, an AC signal for inspection is transmitted to the secondary winding s of the transformer 16 via the secondary winding s and tertiary winding of the transformer 17 and the tertiary winding of the transformer 16. It is becoming more and more common.

An AC signal for inspection is supplied to the line 3b through an inspection signal application circuit consisting of a signal source 19, a transformer 20, and a switch 21. This line 3b is connected to the secondary winding s of the transformer 17.

The input device 15-2 has the same configuration as the input device 15-1, and a switch 23 having the same function as the switch 18 is connected to the tertiary winding. In line 3a,
A detector 24 is connected to detect the suppression output level.

The inspection operation is as follows. First, switch 21 is closed, and switch 18 is closed. By checking the operation of the detector 24 in this state, the health of the input device 15-1 can be confirmed, and
Check the operation of 5-1 and bus protection relay 5.
Next, the switch 18 is opened, the switch 23 is closed, and the health of the input device 15-2 is checked in the same manner. Note that confirmation of this operation is not the gist of the present invention, so a detailed explanation will not be provided. Although not shown, the transformer 20 has a tap so that it can output the minimum operating value of the bus protection relay 5 and values above and below it. If there is a failure in either of the input devices 15-1 and 15-2, the suppression output by the AC signal will not be generated normally.
The detector 24 does not operate normally, and the ratio characteristics of the bus protection relay 5 are affected, and a failure is discovered.

The operation of the detector 24 is determined to be good when the high-level detection elements are inoperative and the low-level detection elements are in operation.

As described above, the transformer of the input device is equipped with a tertiary winding, and the alternating current signal for inspection is selectively passed through this, so it is possible to accurately detect failures in each part of the entire circuit, including the input device. can be detected.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional inspection circuit, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. 1... Bus line, 4-1, 4-2, 15-1, 15-
2... Input device, 5... Bus bar protection relay, 11, 1
8, 21, 23...switch, 24...detector.

Claims (1)

[Claims] 1 A current transformer provided for each of a plurality of lines connected to a bus bar, and a primary winding connected in series with each other so that the secondary current of the current transformer flows, and a secondary winding and a tertiary winding an input device provided for each of the lines, the input device having first and second transformers having the voltage of the first transformer and a rectifier connected to the secondary winding of the first transformer voltage to obtain a DC signal; a first common signal line that guides the DC signal to the bus protection relay; and a second common signal line that leads the AC signal output from the secondary winding of the second transformer of each input device to the bus protection relay. and a level detector connected to the first common signal line to detect the level value width of the DC signal;
an inspection signal application circuit that applies an inspection alternating current signal to the second common signal line only during inspection; a switch that closes a connection path between the tertiary windings of the first and second transformers only during inspection; Inspection circuit with.