JPS58108919A - Energizing device - 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 a power supply device, and particularly to a high-voltage power supply device for supplying power to a repeater on a transmission line over a long distance.

In general, the output of a power supply device is grounded at a neutral point to keep its output potential balanced with the earth, and a constant current supply is used to ensure stable power supply regardless of the number of colors in the repeater or the distance of the transmission line. It is being said. Particularly in long-distance lines, if one of the high-voltage power supply and output terminals is grounded, there is a risk that the output voltage of the other output terminal relative to the earth will rise to twice the normal level.

Also, when a person touches one side of the power supply line, current flows through the human body to the earth, but the potential of the output circuit of the power supply device remains unbalanced with respect to the earth, and the electric current is readable. It is dangerous.

FIG. 1 shows a block diagram of a conventional power supply device using a generally known automatic converter system. In FIG. 1, 1 and 1' are input terminals, 2 and 2' are output terminals, and 3t! Control circuit, 4 is a switching transistor, 5 is a converter transformer, 6 is a rectifier diode, 7 is a smoothing capacitor, 8 is a current detection resistor, 9 is a reference voltage power supply, 10Fi comparison amplifier, 11 is a relay, 11' is a relay 11 contact,
12 and 13 are resistors, 17 is a starting switch, 18 is a load, and 19 is an instantaneous interruption prevention capacitor.

When the start switch 17t is pressed while DC voltage is being supplied between the input terminals 1 and 1', current is supplied to the load 18 through the output terminals 2 and 2', and this current operates the relay 11, which By closing the contact 11', the power supply operation continues even if the activation switch 17 is released.

The switching transistor 4, the converter transistor I5, the rectifier diode 6, the smoothing capacitor 7, and the control circuit 3 constitute a generally well-known self-exciting converter (see Japanese Patent Publication No. 50-15281), and the control circuit 3 includes a tri-sistor. Circuit tP311 that drives the base of 4! t
,, is there. Here, a voltage drop occurs in proportion to the output current due to the current detection resistor 8 which is an impedance element inserted in series in the output circuit, but the amount of this voltage drop is compared with the output of the reference voltage power supply 9. The difference between the two voltages is amplified by the comparison amplifier 10 and then applied to the control circuit 3.

The control circuit 3 adjusts the duty ratio (ratio of conduction time to non-conduction time) of the switching transistor 4 according to this voltage difference.
control. Since this constitutes a negative feedback loop that controls the output current of the converter, a stable constant current is supplied to the output IIc.

The instantaneous power interruption prevention capacitor 19 is a large-capacity electrolytic capacitor that stores charge in order to continuously supply power to the load even if there is a momentary power interruption in the power applied to the input terminals 1, 1'.

This power supply device connects resistors 12 and 13 of equal resistance value as shown in the figure in order to balance the output potential with respect to the earth, provides a neutral point, and only connects this neutral point to the ground. It is. Therefore, even if one of the output lines is grounded, a constant current is supplied to the load side, so that the output voltage of the other output terminal relative to the earth increases to twice the normal level. Furthermore, when a person touches one side of the output line, current flows through the human body to the earth, but power continues to be supplied with the current and voltage of the output line in an unbalanced state.

An object of the present invention is to monitor the unbalanced voltage of the power supply output and stop the operation of the converter using a simple method, thereby preventing an abnormal rise in the power supply output voltage in the event of a grounding accident and preventing a human electric shock accident. The present invention provides a highly safe power supply device that can quickly cut off current flowing to a human body.

In the present invention, the impedances are Zx and Zs, respectively.

Zs and Hi Z4'te & 1lE1. 2', 3 and 84 (
7) A balanced bridge circuit in which impedance elements are sequentially connected in an annular shape and a relationship of ZIZs=ZtZ4 is established between these impedances, and a connection point between the first and fourth impedance elements and the second and third impedance elements. means for applying an output voltage between the connection point of the impedance element and the connection point of the first and second impedance elements; and the connection point of the first and second impedance elements. and a voltage detection means connected between the connection point of the third and fourth impedance elements, and means for stopping the output when the voltage detection means detects a voltage exceeding a predetermined value. A power supply device characterized by:

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 2 is a block diagram showing one embodiment of the present invention. In the figure, 12 to 15 are resistors, 16 is a high-sensitivity relay, and 1
6' indicates the contacts opened and closed by the high-sensitivity relay 16, and the four resistors 12 to 15 constitute a balanced bridge circuit. 14.1! The potential difference with the connection point of S is monitored by a sensitive relay 16. Resistor 12
, 13°, the resistance values of 14 and 15 are R12 and Rt, respectively.
3. If R14 and Rls, R12・R14:R
Since this bridge circuit is designed to be balanced by selecting the resistance value to be 1!1・R16, neither voltage nor current is supplied to the high-sensitivity relay 16 under normal conditions.
.

If one of the output lines is grounded and the potential of the two output terminals 2 and 2' becomes unbalanced with respect to the earth, as in the case where a person touches one of the lines, the resistor 14 Since the potential at the connection point (neutral point) of resistors 12 and 15 deviates from the ground potential, a potential difference appears between the connection point (ground potential) of resistors 12 and 13, and an unbalanced current flows there. Sensitive relay 16 detects even small unbalanced currents, thereby closing the contacts. Contact of contact 16' causes the converter to stop operating and the output current to be supplied. Since the submerged relay 11Fi is demagnetized and its contact 11' is opened, the input circuit is quickly disconnected. High sensitivity relay 16 and its contacts 1
6' may be replaced with an amplifier and a semiconductor switch that is turned on and off by the output of this amplifier. 16 and 16' are yellowtail.

A circuit that detects the unbalanced voltage of the current and a switch that operates when this circuit detects a voltage exceeding a predetermined ratio value will be sufficient. Of course, this voltage detection circuit includes means for converting and detecting changes in voltage into changes in current, such as a relay.

In this embodiment, when the high-sensitivity relay 16 is excited by a current due to an unbalanced voltage, its contact 16' stops the operation of the converter circuit itself. therefore,
Regardless of the charge stored in the instantaneous interruption prevention capacitor 19, the output voltage and current drop rapidly.

Although the constant current power supply device has been described above, the present invention can also be applied to a constant voltage power supply device.

As explained above, the power supply device according to the present invention has a simple circuit configuration and can quickly and reliably stop the operation of the main circuit, thereby preventing the generation of high voltage due to a grounding accident and quickly supplying power even in the event of an electric shock accident. This can effectively prevent personal injury.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional power supply device, and FIG. 2 is a schematic diagram of a power supply device showing an embodiment of the present invention.

Claims (1)

[Claims] The first . Second. third and fourth impedance elements t
ZIZ between these impedances
A balanced bridge circuit having a relationship of s=ZzZ4, and means for applying an output voltage between a connection point between the first and fourth impedance elements and a connection point between the second and third impedance elements. , said! means for grounding all connection points of the first and second impedance elements;
voltage detection means connected between the connection point of the impedance element and the connection point of the third and fourth impedance elements, and stopping the output when this voltage detection means detects a voltage exceeding a predetermined value. A power supply device comprising: means.