JPS59226509A - Filter protecting circuit - Google Patents

Abstract

PURPOSE:To protect effectively a filter without reducing a filter effect by separating a faulty circuit by an overcurrent breaker when a filter is faulty, and supplying continuously a power source to a load by a parallel bypass circuit. CONSTITUTION:In a regular operation, in case of an invasion of a noise voltage from feed lines 20, 21, it passes through overcurrent breakers 32, 50 through connecting parts 22, 24 of protecting circuits 25, 27, led to a filter circuit 26, obstructed by inductances 40, 45, passes through inductances 39, 44, and capacitors 41, 43, led to an earth 23 through a connecting point 42, and a noise is absorbed. When the capacitor 41 of the filter circuit 26 becomes an extremely low impedance, and a feed current flows to the earth through a terminal 23, the breaker 32 operates so as to detach the filter circuit together with a breaker 33. In this way, the feed current route supplies an electric power to a load from a feeder 57 without causing an instantaneous interruption through one of diodes 30, 31, a resistance 29, and a capacitor 28 for absorbing a transient vibration of the switching time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter protection circuit connected in parallel to a power supply line.

In recent years, with the remarkable progress in electronics, the frequency of equipment has increased, and the amount of feedback noise from the load side to the power supply input has increased, causing noise interference to other equipment connected to the same power feed line. , has become obvious. In order to improve the filtering effect of the feed line against such noise, a method has been implemented in which a filter is inserted in series with the feed line to remove noise (see Figure 1). Or, in the event of a failure, the circuit breaker on the power supply line must be disconnected, and the operation of the equipment must be stopped for this purpose.A bypass circuit must be prepared in advance, and especially in the event of a filter failure, sudden equipment and equipment stoppage may occur. There were drawbacks such as the long time it took to repair the filter and to start the device, resulting in enormous losses.

The present invention has been made to eliminate the above-mentioned drawbacks,
Therefore, an object of the present invention is to provide a new protection circuit that can perform maintenance, inspection, and repair work in the event of a failure without stopping the equipment in operation at the time of filter maintenance or failure. There is a particular thing.

In order to achieve the above object, the filter protection circuit according to the present invention has at least one diode, a resistor, and a capacitor connected in parallel, and one end of each of the parallel connected circuits is connected to each other with one end open. The overcurrent circuit breaker is connected, and a parallel connection circuit of a diode and a resistance capacitor is connected in series to the power supply line. In the present invention, when a filter failure occurs due to a drop in the internal impedance of the filter, the overcurrent circuit breaker disconnects the faulty circuit, and the parallel bypass circuit consisting of a diode, resistor, and capacitor continues to supply power. supply to the load.

Next, preferred embodiments of the present invention will be specifically explained with reference to the drawings.

Referring to FIG. 2, a first embodiment of the present invention includes a filter protection circuit of the present invention connected to a power supply line.
Core and filter protection circuit components capacitor g, s
s, resistance 9. jlI, diode 30,3/.

! 2. jJ, 3 overcurrent breakers, ? ,7. ! 0.
g/, filter circuits connected to these protection circuits, and inductance as an example of its components. ? ,
'10.4'4', 4'& and capacitor 41/, 4'
J and the power supply line from its center point to the ground lead terminal 3 and the load! ? , jtt. Next, the operation of the filter protection circuit with the above configuration will be explained.

In normal operation, a protection circuit 2j, :l? protects against noise voltage intrusion from the feed line. Here is the connection.

Overcurrent circuit breaker 32. ! ; 0 is passed through, guided to the filter circuit roller, blocked by inductance yo, lIs, and becomes inductance, 39. '741, capacitor 4
//, through lIj, to earth point 3 via connection point lIλ
noise is absorbed. A high-quality power source with noise removed has a filter output of 3g, and a circuit breaker 33, 3/
Protection circuit exit 3 da, via! 6 through load feed line! It is sent to r7, 3g and connected to the load.

Here, when the capacitors in the filter circuit have extremely low impedance and the current flows to the ground wire through the three terminals, the three circuit breakers in the filter protection circuit detect the overcurrent. It operates to disconnect the filter circuit together with the interlocking circuit breaker 33, and the current feeding route is a diode,
30. Electric power is supplied to the load from the power supply line s7 without momentary interruption via either one of J/, the resistor 9, and the capacitor 2g for absorbing transient vibrations at the time of switching.

In general, in a symmetrical filter circuit like the one shown in the filter circuit column, capacitors 'II and '13 rarely deteriorate at the same time, and since one side operates at normal pressure, the filter effect may decrease. It is possible to continue operating the equipment without disconnecting everything. Further, even if an accident occurs in both circuits, stable power supply can be continuously obtained by the bypass circuit as explained in connection with the protection circuit J.

A first embodiment of the present invention shown in FIG. 3 is a case where the present protection circuit is employed in a DC power supply circuit.

Referring to FIG. 3, the first embodiment of the present invention includes an input feed line (+) t, 2, ←) A/, a main circuit breaker 6, a capacitor 7S, a resistor 76, and a diode hood. , a filter protection circuit 63 consisting of an overcurrent circuit breaker J, 7'l, an electrolytic capacitor 7g, and a load feed line A7,
and a filter 9 consisting of seven filters.

Next, the operation of the first embodiment of the filter protection circuit in the above configuration will be explained. In normal operation, (+
) side through the overcurrent breaker 73 of the filter protection circuit IJ, pass through the (+) side connection point gO of the capacitor 7g of the filter 9, and pass through the overcurrent breaker 71 to the load side power supply line 67,
Furthermore, the return path λ is passed through the capacitor 7g of the filter 9 (
When configured so that the current route passes through the → side g/ to the input side ←) A/, the inductance of the capacitor lead will be reduced if the load circuit becomes a pulse-like current load. By.

The filter effect on the load side is extremely effective, but the electrolytic capacitor 7g also deteriorates faster, and the electrolytic capacitor 7g
The spot phenomenon expands, and a continuous excessive current flows inside the capacitor due to an internal short circuit phenomenon. In this case, the interlocking overcurrent circuit breaker 3 or ? 9 operates to disconnect the capacitor 7g of the filter 79, and the diode, resistor 76, and capacitor 3 continue to supply current to the load.

As a modification of the first embodiment described above, a protection circuit can be connected symmetrically to the capacitor (→ side as well as the (+) side. With such a configuration, an effective filter can be installed. The effectiveness of the filter decoupling circuit is improved.

As explained above, the present invention has an advantage in that the filter can be effectively protected without impairing the filter effect by having the configurations as shown in the first embodiment and A.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional filter protection circuit, FIG. 1 is a circuit diagram showing a first embodiment of the present invention, and FIG. FIG. 2 is a circuit configuration diagram showing an embodiment of the present invention. , 3, 41, 3, ,? ,7. ! 0. ! r/,
? , 7.74'...Overcurrent circuit breaker,! , 21. ,
．． 1-9. ? ? ...filter circuit, 30,3/,,
tco. jJ, ri7...diode 1.29. &lI, 7
4...Resistance patent applicant NEC Co., Ltd. Agent Patent attorney Yutabe Kumagai No. 1 ``1 riζ Figure 2-27'-''----- 3rd session

Claims (1)

[Claims] A filter protection circuit characterized in that at least seven diodes, a resistor, and a capacitor are connected in parallel, and one overcurrent circuit breaker with one end open is connected to each end of the parallel circuit.