JPS6343994B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuse abnormality detection device for detecting abnormalities in fuses provided in each arm of a bridge of a rectifier circuit that rectifies alternating current and supplies direct current power to a load.

Conventionally, there has been a device shown in FIG. 1 as an abnormality detection device for this type of fuse. In the figure, 1 is a three-phase full-wave rectifier circuit that is connected to an AC power supply via a circuit breaker 2, rectifies AC and supplies DC power to a load 3, and each arm that makes up the bridge of this rectifier circuit has A series body of a rectifier 4 and a fuse 5 is inserted in each. However, 6 is the fuse 5 above.
A contact point mechanically connected to the fuse 5 is closed when the fuse 5 is blown, thereby forming a closed circuit and generating an abnormal signal.

In the fuse abnormality detection device having the above configuration, the three-phase full-wave rectifier circuit 1 inputs three-phase AC from an AC power source (not shown), rectifies it with a rectifier 4, and supplies it to the load 3 as DC power via the fuse 5. However, in the event of an abnormality such as a short circuit, the rectifier 4 and fuse 5 inserted in each arm constituting the bridge of the three-phase full-wave rectifier circuit 1
An excessive current will flow through the series body, which will blow out the fuse 5 and prevent the abnormal situation caused by the excessive current from continuing. Then, as the fuse 5 is blown, this fuse 5
The contact point 6 mechanically connected to is closed to form a closed circuit, generating an abnormality signal for the fuse 5. This abnormality signal is appropriately input to a processing circuit and used as a fuse 5 blowout alarm or an operation stop command. It turns out.

However, with conventional equipment, abnormality detection of a fuse can only be performed if the fuse has the rated capacity, but if the fuse does not have the breaking capacity due to manufacturing defects etc. Since this defective fuse does not blow out, the fault current continues to flow, which not only makes it impossible to detect an abnormality, but also increases the internal pressure of the fuse, causing an explosion and amplifying the fault.

Therefore, the present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional ones, and is capable of detecting the state in which the fuse cannot be blown, and can prevent the spread of accidents due to the inability to blow the fuse. A detection device is provided. More specifically, the present invention detects the current flowing through a rectifier circuit provided with a fuse in each arm constituting the bridge, detects the rising and falling pulses of the current, and detects an abnormal arrangement of this pulse signal, that is, The present invention provides an abnormality detection device that detects an abnormality in the current flowing through the rectifier circuit by detecting an abnormality in the periodic generation of rising and falling pulses, thereby generating an abnormality signal for the fuse. be.

Hereinafter, one embodiment of the present invention will be explained based on the drawings. In FIG.
7, 7 are respectively provided, and a pulse transformer 8 is connected to the secondary winding side of each current transformer 7.
Further, an abnormality detector 9 is provided on the secondary side of the pulse transformer 8, which outputs an abnormal signal of the fuse 5 provided in each arm of the rectifier circuit 1 by detecting an abnormal arrangement of pulse signals output from the pulse transformer 8. As is well known in the art, this abnormality detector 9 counts rising pulses output from the pulse transformer 8 as up signals and falling pulses as down signals, and also counts falling pulses as up signals and rising pulses as up signals. Rectification is performed by counting pulses as down signals and detecting abnormalities in the periodic generation of rising and falling pulses when any of these count outputs continues for a predetermined period of time or more as a non-zero value. It is designed to detect an abnormality in the current flowing through the circuit 1, and in turn, to detect an abnormality in the fuse 5. In addition, 4U ₁ , 4U ₂ , 4V ₁ , 4V ₂ , 4W ₁ ,
4W ₂ is a rectifier element provided in each arm of the rectifier circuit 1, and its symbol is shown corresponding to the input lines U, V, and W.

In the fuse abnormality detection device having the above configuration, each input line U, V,
The currents shown in Figure 1 a, b, and c flow through W,
This current is detected by each current transformer 7. Therefore, since the primary current on the secondary side of each current transformer 7 is a rectangular wave as shown in FIG. 3 a, b, and c, the current waveforms shown in FIG. Voltages are induced at the rising and falling times to generate rising and falling pulses, respectively. These rising and falling pulses are then input to an abnormality detector 9 via a pulse transformer 8. At this time, the abnormality detector 9
3e, as long as the rectifier circuit 1 is normal.
As shown in f and g, rising and falling pulses with a normal arrangement are input, and each count output has a rising pulse (and falling pulse) as an up signal and a falling pulse (and rising pulse) as a down signal. It becomes 0 periodically and no abnormal signal is output.

That is, each count output periodically repeats counting from 1 to 2 to 1 to 0. As an example, each count value in FIG. 3g is shown.

However, as shown in FIG. 3d, for example, α
Even though a short-circuit failure has occurred in the rectifier circuit 1 in the section, the fuse 5 does not respond to this current and cannot be blown, that is, even though the rectifier 4W ₁ shown in FIG. 2 is in a short-circuited state. Considering the molten state in which the fuse does not blow out, the rectifier 4
A short circuit current flows to the W phase from U ₁ , 4V ₁ , and as shown in Fig. 3d.
As a result, the rising and falling pulses as shown in FIG. The difference between Figure c and Figure 3D, which shows the current waveform at the time of abnormality, is that one of the count outputs that counts up and down based on the rising and falling pulses cannot periodically become 0, and the pulse signal arrangement is abnormal. , an abnormality in the current flowing through the rectifier circuit 1 is detected, and an abnormality signal indicating the melted state of the fuse 5 is output.

In other words, as shown in the count value shown in Fig. 3h, when a rising pulse is used as an up signal and a falling pulse is used as a down signal, the process of 1 → 2 → 1 → 2 is repeated, and 0 output is obtained periodically. I can't do it,
On the other hand, counting in which the falling pulse is used as an up signal and the rising pulse is used as a down signal repeats 1→0→1→0, and a 0 output is obtained periodically. Therefore, in this case, the rising pulse is turned up,
An abnormal signal is obtained by a counter that uses a falling pulse as a down signal.

In the above embodiment, when the load 3 is a brushless synchronous machine, a rotary pulse transformer can be used as the pulse transformer 8 and installed on the rotor of the brushless synchronous machine, and in this case, the abnormality detector 9 is installed on the fixed side, and the current transformer 7 and the primary side of the pulse transformer 8 are installed on the rotor.

Further, in the above embodiment, the current transformer 7 is provided in the AC input lines U, V, W, but it may also be provided in each arm of the rectifier circuit 1, and the same effect as in the above embodiment can be obtained.

As described above, according to the present invention, the rectifier circuit detects the current flowing through the rectifier circuit, generates rising and falling pulses of the current, and detects abnormalities in the periodic generation of the rising and falling pulses. Since an abnormality in the current flowing through the fuse is detected and a fuse abnormality signal is output, it is possible to detect the inability to blow the fuse, and prevent the spread of an accident due to the inability to blow the fuse.

[Brief explanation of the drawing]

Fig. 1 is a schematic circuit diagram of a conventional fuse blowout detection device, Fig. 2 is a circuit diagram showing a fuse abnormality detection device according to an embodiment of the present invention, and Fig. 3 is an operation waveform diagram of each part of Fig. 2. It is. 1: Rectifier circuit, 5: Fuse, 7: Current transformer,
8: Pulse transformer, 9: Abnormality detector. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Pulse generating means that detects the current flowing through a rectifier circuit that rectifies alternating current and supplies direct current power to a load, and generates rising and falling pulses of the current;
By detecting an abnormality in the periodic generation of the rising and falling pulses from the pulse generating means, an abnormality in the current flowing through the rectifying circuit is detected, and a fuse provided in each arm constituting the bridge of the rectifying circuit is detected. An abnormality detection device for a fuse, comprising: an abnormality detector that outputs an abnormality signal.