JPS59162721A - Rush current preventng circuit - 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 The present invention relates to an inrush current prevention circuit that reduces inrush current that occurs when power is turned on in a communication device or the like.

FIG. 1 shows a conventional inrush current prevention circuit. In general, in power supply circuits used in communication devices, when the power is turned on,
In the case of an AC input power supply circuit system, a single magnetic flux change of the transformer enters the saturation region, causing a reflected current, and in the case of a DC input power supply circuit system, a large amount of charging current flows into the capacitor, which has a negative impact on the station power supply equipment. In some cases, the rated load of the station power supply equipment is greatly exceeded, making it impossible to supply power.

In Figure 1, when the contacts 3 of the relay 2 are open and the power supply switch 5 is closed, the current limiting resistor 1 limits the current, and the operation of the relay 2 is controlled by the capacitor 4 for a period of time during which the input current is stabilized. After a delay, the current limiting resistor 1 is short-circuited by the contact 3 of the relay 2, and steady operation begins without power loss.

In such an inrush current prevention circuit, the delay time of the resistance value control relay 2 of the current limiting resistor 1 is determined by the delay time of the current limiting resistor 1, the relay 2, and the capacitor 4 connected in parallel to the relay 2 when the power is turned on. When the power is turned off, it is uniquely determined by the value of the relay 2 and the capacitor 4 connected in parallel to the relay 2. Therefore, when the switch 5 is opened and closed quickly, the contact 3 of the relay 2 is closed. Since the power supply is turned off and on, there is a drawback that the current limiting resistor 1 does not operate effectively.

The present invention has been made in view of the drawbacks, and an object of the present invention is to provide a switch circuit consisting of a voltage detection circuit, a delay circuit, and a relay, thereby speeding up the process from disconnection to reconnection by manual switch operation. The object of the present invention is to provide an inrush current prevention circuit that can prevent inrush currents regardless of the situation.

In order to achieve the above object, the present invention provides an inrush current prevention circuit configured with a resistor that limits current and a relay that controls the resistance value of the resistor, including a voltage detection circuit, a delay circuit, and a relay. It has a switch circuit consisting of. That is, in the present invention, when a switch is operated to open, a relay contact interlocked with a voltage detection circuit is opened, and when the switch is then operated to close, a delay circuit causes the switch to close the relay contact later. , which is characterized by preventing inrush current without being affected by the artificial opening/closing speed of the switch.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 2 is a block diagram showing an embodiment of the inrush current prevention circuit of the present invention.

In the figure, power from the station power supply equipment is connected to a power-on switch 5, a contact 9 of a relay 8, and a current limiting resistor 1, and is supplied to nine loads (not shown). Also, relay 2
A capacitor 4 is connected to the load side of the current limiting resistor 1 and the return circuit 10.

Further, resistance value limiting contacts 3 are connected to both ends of the upper current limiting resistor 1 . The present invention further provides a voltage detection circuit 6 connected between the switch 5 and the contact 9 and to the return circuit 10, a relay 8 that turns on and off the contact 9, and a voltage detection circuit 6 between the voltage detection circuit 6 and the relay 8. delay circuit 7 connected to
It has a switch circuit composed of.

In such a connection, in the initial state, contacts 9 and 3 are open, and when switch 5 is closed and voltage is applied,
The voltage detection circuit 6 operates and gives a signal to the delay circuit 7, and after a certain period of time has elapsed, the electrical appliance 8 operates and its contact 9 closes. This connects the resistor 1 in series with the load and prevents inrush current. Then resistance 1. After a period of time determined by the relay 2 and the capacitor 4 has elapsed, the contacts 3 of the relay 2 are closed and a specified voltage is applied to the load.

Next, when the switch 5 is opened, if no voltage is detected by the voltage detection circuit 6, the voltage supply circuit of the relay 8 is disconnected, and the contact 9 is not affected by the delay circuit 7. opens. At this time, the relay 2, the capacitor 4, and the contact 3 continue to be closed, and the current limiting resistor 1 is short-circuited.

In this state, when the switch 5 is closed, the voltage detection circuit 6 is activated, a signal is given to the delay circuit 7, and the relay k8 is not activated for a certain period of time. After that, the charge in the capacitor 4 is consumed, the relay 2 returns to normal, and the contacts 3 become open.
Contacts 9 of relay 8 close, supplying voltage to the load.

As explained above, the present invention provides 16. Pressure detection circuit.

By providing a switch circuit consisting of a delay circuit and a relay, there is a great effect of preventing inrush current without being affected by the opening/closing speed of the switch.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional inrush current prevention circuit, and FIG. 2 is a block diagram showing an embodiment of the inrush current prevention circuit of the present invention. 1...Resistor 2...Relay 3...Contact 4...Condenser 5...Switch
6... Voltage detection circuit 7... Delay circuit
8...Relay 9...Contact 10...
・Return circuit applicant: NEC Corporation Figure 1 Figure 2

Claims (1)

[Claims] An inrush current prevention circuit comprising a resistor that limits current and a relay that controls the resistance value of the resistor, comprising a switch circuit comprising a voltage detection circuit, a delay circuit, and a relay. , the above-mentioned relay opens the contacts in conjunction with the above-mentioned voltage detection circuit when the power supply switch is opened,
An inrush current prevention circuit characterized in that when the switch is closed, the delay circuit closes the contact after a certain period of time.