JPS5961430A - Power source filter circuit system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a power filter circuit system, more specifically,
In order to limit the charging current of the capacitor that constitutes the filter, a series resistor and a contact point for shorting the series resistor are provided,
A power supply filter circuit system in which the inrush current of the filter is suppressed when the power is turned on, and the series resistor is short-circuited by closing the contacts after charging is completed (related to -).

Prior Art and Problems In a telephone exchange system, in order to absorb the noise generated by the power supply and prevent it from adversely affecting telephone calls, the noise generated by the power supply is transmitted from the power supply to the telephone via a power filter and through the telephone line. Supply electricity.

There are power supply filters with configurations such as the π type, which has a capacitor connected directly to the input ('), and the L type, which has a capacitor connected to the input via an inductance.When a power supply is connected to this filter, the capacitor It is connected to the power supply directly or through an inductance with low DC resistance, and an excessive inrush current flows as the charging current of the capacitor.To prevent this, the capacitor (2) are connected in series, and when the power is turned on, charging is performed through the resistor to suppress the rush current, and after the power is turned on, charging is performed for a certain period of time, and then the resistor is short-circuited.

FIG. 1 is a connection diagram of an example of this type of power supply filter circuit system according to the prior art.

In Fig. 1, Fil is a filter, which has an L-shaped configuration consisting of an inductance L and a capacitor C (2), where Re is a resistance for limiting rush current, ?-0 is a contact of relay R, and F is a fuse. .SD is a power-on detection circuit,
DB is a delay circuit, and R is a relay.

FIG. 2 is a connection diagram showing details of the delay circuit DE of FIG. 1. In FIG. 2 (-), ST is a starting relay, Co is a capacitor, Ro and R* are resistors, and T is a delay device that applies a certain delay to an input and outputs the output, and can be configured with a timer, for example.

When the power is turned on, a DC voltage of the corresponding polarity is applied to the + terminal, and at this time, since the capacitor C is in a discharged state, in addition to the current flowing to the load, the + terminal and the inductance L
, capacitor fc, and resistor Ee to one terminal (=charging current flows, but its magnitude is limited by resistor Re. When the power is turned on, the voltage from the child wire from the + terminal is output as the power-on detection output. Output terminal Ou of power-on detection circuit SD
t and input to the delay circuit DE.

As shown in FIG. 2, the starting relay ST of the delay circuit DE is activated by the output of the power-on detection circuit SD, and its contact ST
Convert 0. Since one electrode of the capacitor Co is connected to the terminal wire (two wires) by the switched contact st0, the capacitor Co starts charging through the resistor Ro.Charging progresses and the voltage at the above electrode of the capacitor Co, that is, the delay When the input voltage to the device T reaches a certain value, the delay device T is activated and produces an output after a certain delay time, which activates the relay R.The delay device T receives a certain voltage and then outputs an output after a certain delay time.
It produces an output after a certain delay and then sends out the output as long as there is an input.

In this way (2. After the power is turned on, the relay R operates after a certain delay, closes its contact r0, and short-circuits the resistor Re.
Filter F'il begins to perform a predetermined operation, and at this time, charging of capacitor C (2) has also been completed, so no excessive inrush current flows.

If the power is cut off, the filter I'il conden-9
The charge on -C is discharged through the load, and the voltage between the - lines gradually decreases. If it falls below the level where it becomes.

The power-on detection output voltage of the power-on detection circuit SD decreases, so that the relay ST of the delay circuit DE is restored, and its contact ST
0 is restored, the capacitor Co connects with the resistor R1 and the contact s
Discharging after t0, the input voltage of the delay device T disappears, it loses its output, the relay R is restored, and the filter Fil returns to its initial state.

However, through the load of capacitor C of filter Fil, 1
The discharge that occurs takes time because the capacitance of the capacitor fC is large, so it takes time for the voltage between the wires to drop, and the delay device T loses its output due to the restoration of the relay ST and the discharge of the capacitor Co. It takes a certain amount of time for relay R to recover.

However, if the power is turned on again before the relay R has recovered after the power is cut off, the filter C' will be connected to the contact r"fl'
It is connected to a power source and is charged without a current limiting resistor. This may occur due to

Therefore, with the above-mentioned conventional power supply filter circuit system, depending on the state of charge in capacitor C when the power is turned on again, an excessive inrush current may flow, causing fuse F to melt and various other inconveniences. There was a drawback that there was a high possibility that something would happen.

Purpose of the Invention The present invention eliminates the above-mentioned drawbacks of the conventional power supply filter circuit system, and provides a power-on switch, a power supply connection connector, etc. after the inrush current limiting resistor of the power supply filter is short-circuited after the power supply is turned on. It is an object of the present invention to provide a power supply filter circuit system with good operational performance so that fuse blowing and other inconveniences do not occur even when cutting and turning occur in succession.

Examples of the invention Embodiments of the present invention will be described below with reference to the drawings.

FIG. 6 is a connection diagram of an embodiment of the present invention, and FIG. 4 is a connection diagram of an example of the delay circuit of the embodiment of FIG.

In FIG. 6, the symbols are the same as those in FIG. 1, and the embodiment of the present invention shown in FIG. The difference is that the stationary contact r1 of relay R is inserted in , and the configuration of delay circuit DE differs from that shown in FIG.

In Fig. 6, if the power is turned on and a DC voltage of the corresponding polarity is applied to the
A charging current flows to one terminal through the resistor Re, but its magnitude is limited by the resistor Re so as not to affect each device. It is output from the output @ Chbt and is input to the delay circuit DE via the static contact γ1 of the relay R as a power-on detection output.

In the embodiment of FIG. 6, the configuration of the delay circuit DE is $
Unlike the one in Figure 2, it is as shown in Figure 4.

In FIG. 4, the output of the power-on detection circuit SD operates the starting relay ST of the delay circuit DE, and its contact s
t0 changes. Charging of the capacitor Co starts from the one line and one line via the switched contact zt0 and the resistor RO. When charging progresses and the voltage of the electrode of the capacitor Co connected to the input end of the delay device T, that is, the input voltage of the delay device T, reaches a certain value, the delay device T is started and the voltage reaches a certain level. Produces an output after a delay time and sends the output as long as the input is present.

This output operates relay H, which closes its own contact h0 (C), holds itself through resistor R2, and closes contact AI (outputs the voltage of the second strand wire, relay R (-) and make it work.

Closing of contact r0 (from the second point, the current limiting resistor Re is short-circuited, and the filter Fil begins to operate with the specified characteristics. At this time, the charging of the capacitor C has also been completed, so that no excessive inrush current flows. do not have.

By opening the contact rI, the operating circuit of the starting relay ST is interrupted and restored, and by the restoration of the contact st0, the capacitor Co is discharged through the resistor R+, the input to the delay device T disappears, and therefore its output also disappears. do. However, the relay H holds the output of the delay circuit T (1) through the self-contact h0 regardless of the closing of the contact h1 (2).

In the embodiment shown in Fig. 3, as described above (= relay R is inactive until a certain period of time has passed after the power is turned on, capacitor C of filter Fil is charged via resistor Re, and excessive inrush current is suppressed. However, the relay R that completes charging operates to short-circuit the resistor Re, as in the prior art shown in FIG.

However, when the relay R operates, the contact r1 is opened, so that the relay ST of the delay circuit DE is restored, and the capacitor Co is discharged, so that the input to the delay device T is lost. However, relay R is held by contact h1.

When the power supply is cut off, the charge in the capacitor C of the filter Fil is discharged through the load, and the voltage between the + and - lines gradually decreases (=
descend. When the voltage drops to such a level that
Relay R is restored by opening '. By closing the contact τ1, the delay circuit DE returns to its initial state and is ready for next use.

When the relay R is restored, the contact r0 is opened, and the short circuit of the resistor Re is released.

If the power is turned on in this state, the operation as described above when the power is turned on for the first time will be performed, and the operation of the relay R will be suppressed for a certain period of time after the power is turned on, so that the charging current to the capacitor C will be transferred to the resistor Re. limited by.

In this way, when the power is turned on and relay R operates, the delay device T immediately loses its input to partially prepare for a new operation, and when the power is cut off, relay R is restored and the current limiting resistor Remove the short circuit on Re, return to the initial state, and be fully prepared for the next new operation. When the power is turned on again, the normal operation described above when the power is turned on for the first time is performed, and excessive inrush current is suppressed.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope thereof.

Effects of the Invention Since the power supply filter circuit system according to the present invention is configured as described above, excessive inrush current is automatically suppressed when the power is turned on, and after the suppression is released, specifically, For example, in the above embodiment, even if the power source is successively cut off and turned on after the relay R is operated, generation of an excessive rush current can be prevented.

[Brief explanation of drawings]

Figure 1 is a connection diagram of an example of a conventional power supply filter circuit system.
2 is a diagram showing a detailed configuration of a conventional power-on detection circuit used in the conventional power supply filter circuit system C2 shown in FIG. 1, and FIG. 6 is a connection diagram of an embodiment of the present invention. FIG. 4 is a diagram showing a detailed configuration of the power-on detection circuit used in the embodiment of FIG. 5. Fil...filter, L...inductance, C
,C. ...Capacitor, F...Fuse, Re, Ro
, R+, R2...resistor, SD...power-on detection circuit, DE...delay circuit, T...delay device, R
, ST, H... Relay (lowercase letters indicate contacts) Patent applicant: Fujitsu Limited Agent Patent attorney: Gobe Tamamushi (6 people included) Figure 1 Figure 2 Figure 10 Figure 3 Figure 4 Figure 10

Claims (1)

[Claims] A power source filter includes a series resistor for limiting the charging current of a capacitor constituting the filter and a contact for shorting the series resistor; A delay circuit that operates in response to a power-on detection output output from a medium power-on detection circuit, and a relay that operates based on the output of the delay circuit and is equipped with a contact for shorting the series resistor, When the power is turned on, the delay circuit is activated by the power-on detection output of the power-on detection circuit, and after a certain period of time, the above-mentioned relay is operated to short-circuit the series resistance of the capacitor and the delay device of the above-mentioned delay circuit is restored. 1. A power supply circuit system characterized in that, in the event of a cutoff, the relay restores the short circuit of the resistor and returns the delay circuit to its initial state.