JP2570657Y2 - Abnormality detector for capacitor device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detecting device for a capacitor device.

[0002]

2. Description of the Related Art It is well known that a capacitor element formed by assembling a plurality of capacitor elements is housed in a case to constitute a capacitor device. In such a capacitor device, it is sometimes required to monitor the occurrence of partial discharge in order to detect an abnormality of the capacitor body, for example, a state before destruction, as predictive maintenance of the capacitor body.

FIG. 3 shows a conventional example. This example is a single-phase capacitor device, in which 1 is a capacitor body, 2 is a case, and 3 is a pushing used to lead out leads 4 from both ends of the capacitor body 1 to the outside.

When monitoring the occurrence of partial discharge of the capacitor element in such a configuration, the capacitor device is disconnected from the system bus or load, and a transformer for detecting partial discharge, such as a current transformer, as shown in FIG. Prepare 5 The center tap 7 of the primary coil 6 of the current transformer 5 is grounded.

[0005] One end of the capacitor body 1 is connected to one end of the primary coil 6, and the other end of the capacitor body 1 is connected to the other end of the primary coil 6 via a dummy capacitor 8.
An AC power supply 9 is connected to a circuit that connects the other end of the capacitor body 1 and the dummy capacitor 8. The measuring device 11 is connected to the secondary coil 10 of the current transformer 5.

Here, assuming that the capacitor body 1 and the capacitor 8 have the same capacity, and that no partial discharge occurs in the capacitor body 1, the primary coil 6 of the current transformer 5 has both ends thereof. The currents I1 and I2 flowing from are equal. Therefore, theoretically, the secondary current induced in the secondary coil 10 is zero.

On the other hand, when partial discharge is occurring in the capacitor body 1, the current I1 becomes larger than the current I2, thereby inducing a secondary current in the secondary coil 10.
By measuring this with the measuring device 11, it can be detected that partial discharge has occurred in the capacitor body 1.

However, according to such a configuration, when the partial discharge is to be detected, the capacitor device must be disconnected from the system bus, so that the operation of the condenser device must be interrupted, and therefore, the partial discharge must be performed. The occurrence of discharge cannot be constantly monitored. In addition, a dummy capacitor 8 having substantially the same capacity as the capacitor body 1 must be prepared, and moreover, a capacitor which does not generate partial discharge at a voltage lower than the measured voltage is inconvenient.

FIG. 4 shows a conventional example for detecting occurrence of partial discharge in a three-phase capacitor device. In this case, two of the capacitor elements 1 of each phase are alternately selected and connected in series. This is performed by connecting to one end of the primary coil 10 of the current transformer 5. Even in this case, constant monitoring is not possible, and a dummy capacitor must be prepared.

[0010]

SUMMARY OF THE INVENTION The present invention makes it possible to constantly monitor the detection of an abnormal state, such as partial discharge, of a capacitor element constituting a capacitor device. It is another object of the present invention to eliminate the need for a dummy capacitor.

[0011]

According to the present invention, a capacitor element to be monitored is divided into two for each phase, and one end of each of the divided capacitor elements is placed inside a tank containing the capacitor element. connected to each end of the primary coil and a transformer centers taps are installed, connected to the system bus in a lump the other ends of each split capacitor body, transformer of the secondary
Connect both ends of the secondary coil to the tank via the terminals provided in the tank.
Out of the tank and by a measuring instrument outside the tank
Characterized in that to detect the abnormality I.

[0012]

The number of capacitor elements constituting each divided capacitor element is arbitrary, but it is desirable that the capacitance of each divided capacitor element be substantially the same. If no partial discharge has occurred in each divided capacitor element, no current flows through the primary coil of the transformer , or only a small amount of current flows based on the difference in the capacitance of each divided capacitor element. is there.

[0013] When one partial discharges of the divided capacitor body had Ji raw, current flows through the primary coil of the transformer. The measuring device operates based on this current, and the occurrence thereof can be detected.

According to this configuration, it is possible to detect the occurrence of partial discharge while the capacitor device remains connected to the system bus. That is, constant monitoring is possible without interrupting the operation of the capacitor device. Further, it is not necessary to use a dummy capacitor as in the related art.

[0015]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is an example of a single-phase capacitor device, and portions denoted by the same reference numerals as those in FIG. 3 indicate the same or corresponding portions.
According to the invention, the capacitor element to be monitored is divided into two parts. Each split capacitor element is shown as 1A, 1B.
The number of capacitor elements included in each divided capacitor element body 1A, 1B may be the same or different, but if the combined capacitance of each divided capacitor element element 1A, 1B is substantially the same, This is convenient because the sensitivity is increased.

One end of each of the divided capacitor bodies 1A and 1B is connected to each end of the primary coil 6 of the current transformer 5, and the other end is collectively connected to the system bus 12. In this case, the center tap 7 is grounded. The secondary coil 10 of the current transformer 5 is led out of the case 2 via the terminal 13 and connected to the measuring device 11.

In the above configuration, if there is no abnormality in both split capacitor element bodies 1A and 1B, currents I1 and I2 flowing through split capacitor element bodies 1A and 1B are equal, and current flowing through secondary coil 10 of current transformer 5 becomes equal. No current is induced.

However, when a partial discharge occurs in one of the divided capacitor elements, a difference occurs between the currents I1 and I2, so that the secondary current of the current transformer 5 has a current corresponding to the difference. Induce. By measuring the induced current with the measuring device 11, it becomes possible to detect which of the divided capacitor elements has a partial discharge.

FIG. 2 shows an example in which the present invention is applied to a three-phase capacitor device. The capacitor body 1 of each phase is divided into two parts as in FIG. Then, the current transformer 5 is connected to the divided capacitor element body of each phase in the same manner as in FIG. In this case, the neutral point is connected by connecting the center taps 7 of the current transformers 5 of each phase collectively.

[0020]

According to the present invention, as described above, the occurrence of an abnormal state such as partial discharge of a capacitor element can be constantly monitored without interrupting the operation of the capacitor device. It is no longer necessary to use a dummy capacitor as in the past, and a transformer, such as a current transformer, used to detect the occurrence of an abnormal condition is installed in the tank together with the capacitor element. This eliminates the possibility of picking up noise and induction, thereby improving the measurement sensitivity.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit diagram showing a conventional example.

FIG. 4 is a circuit diagram showing another conventional example.

[Explanation of symbols]

 Reference Signs List 1A Split capacitor element 1B Split capacitor element 2 Case 5 Transformer (current transformer) 6 Primary coil 7 Center tap 10 Secondary coil 11 Measuring instrument

Claims (1)

(57) [Scope of request for utility model registration] 1. A capacitor element to be monitored is divided into two for each phase, and one end of each of the divided capacitor elements is connected to a center of a transformer installed in a tank containing the capacitor element. Connect to each end of the primary coil provided with taps, connect each other end of each of the divided capacitor element bodies to a system bus collectively, and connect both ends of the secondary coil of the transformer.
Lead out of the tank via the terminal provided on the tank
And an abnormality detecting device for the capacitor device, which is measured by a measuring device outside the tank.