JPS617478A - Detection of earth position - Google Patents

Abstract

PURPOSE:To make it possible to easily detect the region where earth is generated, by detecting magnetic flux due to the earth current flowed to the relay coil of a sequence circuit containing earth when the insulating resistance of the sequence circuit is tested. CONSTITUTION:The earth current I by an insulating resistance test flows in a route of the probe D of an insulating resistance meter M power source terminal power source matrix line terminal Ty relay coil Ry earth point Y earth resistor Z insulating resistance meter probe E. At this time, magnetomotive force proportional to the magnitude of the current I is generated in the relay coil Ry and magnetic flux is generated. Therefore, the magnetic sensor H of magnetic flux detection machinery G is contacted with relay coils Ra, Rb... Ry, Rz in this order and the generation of magnetic flux in the coil Ry is detected to make it possible to simply detect that there is the earth point Y in the sequence circuit of the coil Ry without separating off the sequence circuit from a power source matrix wire.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for detecting a ground fault location in a beam resistor circuit.

[Background of the invention]

A conventional ground fault location detection method will be explained. General glue range
The can circuit is shown in Figure 1. Power (+) (-) is supplied to terminals P and N of the switch S and to the stain source bus. Relay R1
is the (+) side power supply bus connection terminal] 1, a contact A, b
Contact B is connected to the connection terminal T of the relay coil R111(-) power supply bus via many other A contacts and B contacts, forming one sequence circuit. Similarly, power bus terminals Xb...Xa X7. There are also many A contacts,
The relay coils Rh...R, R, , reach the power supply bus terminals Tb...T, T, respectively. Now, terminal X,
Assume that a ground fault occurs at point Y in the sequence circuit between and 17, and the ground fault resistance is ZΩ. Generally, to test the insulation resistance of an electric circuit, open the switch S, short-circuit terminals P and N with a clip cord Q, and measure the insulation resistance by placing the measuring glove D of the insulation resistance meter M on either terminal P or N. Measure. In other words, ground faults related to the power supply bus are measured, but the presence or absence of a ground fault can be determined by an insulation test. However, the location of the ground fault point Y cannot be detected. Therefore, in order to discover the ground fault point Y,
Connect the power bus connection terminals to X, T,, XbTb,...Xy
Disconnect each relay sequence circuit from the power supply bus in the order of T@ Continue until. In the case of Figure 1, when terminal T is disconnected, the ground fault point Y is disconnected from the power supply bus, and the insulation resistance meter M shows ψΩ, so it is assumed that the ground fault is related to terminal T. The ground fault position is searched by determining the ground fault point Y and then carefully checking the sequence circuit connected to the terminal Ty to discover the ground fault point Y. In this method, as the number of relays connected to the power supply bus increases, the number of connection terminals also increases.When tens or hundreds of relays are connected, the conventional method has the disadvantage of being extremely time-consuming. .

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method that allows easy exploration of a location where a ground fault has occurred.

[Summary of the invention]

The key point of the invention is that when testing the insulation resistance of a relay sequence circuit that includes a ground fault, the magnetic flux generated by the ground fault current flowing through the relay coil of this sequence circuit is detected, and the location of the ground fault is searched based on the presence or absence of this magnetic flux. It's what I chose to do.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. For ground fault current measurement using insulation resistance test, use probe D of insulation resistance tester.
→ Power terminal → Power bus terminal TA → Relay coil RA → Ground fault point Y → Ground fault resistance Z → Insulation resistance meter probe E. At this time, a magnetomotive force proportional to the magnitude of the current I is generated in the relay coil Ra, but no magnetomotive force is generated in the other relay coils because the voltage increases but no current flows. In this way, only the coil R generates magnetomotive force and emits magnetic flux. Then, when the magnetic sensor H of the device G that detects magnetic flux is applied to the relay coils R-, Rb, . The presence of a ground fault point Y in the sequence circuit of Ra can be easily detected without separating the sequence circuit from the power supply bus as in the conventional method.

In the example shown in Figure 2, an insulation resistance meter is used as the test power source, but since the value of the ground current is only a few mAL at most, the performance of the magnetic flux detector G is highly sensitive and stable. equipment.

FIG. 3 shows a configuration diagram of an example of a magnetic flux detector having the above-mentioned performance. High gain output of magnetic sensor H.

The signal is amplified by a highly stable amplifier 1, output to a filter 2 that removes amplifier noise, and the output is divided into two. One side is input to the automatic O balance adjuster 3 of the amplifier 1 and returned to the amplifier 1 in order to prevent the influence of residual magnetism of the relay to be detected. The output of the other filter is input to the comparator 4 and compared with the output of the reference voltage generator 5. If the output of the amplifier is higher than the reference voltage, the display 6 is driven to display the presence or absence of magnetic flux. It is. Figure 4 shows how to apply the relay coil of sensor H of the magnetic flux detector. In order to increase the magnetic sensitivity, it is necessary to place a magnetic sensor H (in the magnetic path) between the fixed iron core V of the relay R and the movable iron piece. Note that there is no problem even if the test power supply is a power supply device other than an insulation resistance meter, and any power supply that can flow a current of ten or more mA will be advantageous for detecting magnetic flux.

〔Effect of the invention〕

According to the present invention, the ground fault position can be easily determined by measuring magnetic flux.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional ground fault location detection method, Fig. 2 is an explanatory diagram of an embodiment of the present invention, Fig. 3 is a configuration diagram of a magnetic flux detector of the present invention, and Fig. 4 is a magnetic detection sensor. FIG. G...Magnetic flux detector, H...Magnetic sensor, ■...
Earth fault is also shown in figure 1 and figure 2 (10) (-).

Claims (1)

[Claims] 1. When a test voltage is applied between the power supply terminal of a sequence circuit consisting of multiple relays and the ground, the ground fault current flowing to the ground fault position in the sequence circuit causes magnetic flux generated by flowing to the relay coil. A ground fault location detection method characterized by detecting.