SU1632677A2 - Device for controlling welding current sources - Google Patents

Abstract

The invention relates to welding, can be used in shipbuilding, mechanical engineering and other industries of the industry and is intended to control the operation of a group of sources of welding current connected to the welding busbar. The purpose of the invention is to increase the service life of welding current sources by eliminating the frequent switching on and off of sources with a sudden change in the load current in the welding busbar. A device for controlling the operation of a group of welding current sources contains an input amplifier, two threshold elements of the upper and lower switching current values, a logic unit with a clock generator and a zero-setting element of the logic unit. The D / A converter changes the switching threshold of the lower switching current value. The on and off elements of the first power source and the electronic relay unit provide for switching the welding current power sources on and off. The device is equipped with an on / off logic element of the pulse generator of a clock generator, a pulse counter of the clock generator and an element of logic switching of a logic unit. When the load current of the first source changes, its load level is estimated, which leads to automatic connection or disconnection of subsequent welding current sources. 1 il. and (L

Description

The invention relates to the automation of welding production, can be used in all sectors of the industry where there are groups of welding current power sources operating on a common busbar and is an improvement of the device according to the author. St. No. 1328104.

The aim of the invention is to increase the service life of welding current sources by eliminating the frequent switching on and off of sources with a sudden change in the load current in the welding busbar.

The drawing shows a functional block diagram of the proposed device.

A device for controlling the operation of a group of welding current sources comprises

input amplifier 1, two threshold elements of the upper 2 and lower 3 values of the switching current, logic unit 4 with a clock generator 5 and an element 6 for setting the logic unit to zero position, digital-to-analog converter 7, block 8 electronic relays, switching on and off elements 10 of the first source , an electronic relay 11, a power supply unit 12 and a shunt 13 of the first source 14. The power sources 15-23 and the first source 14 are connected to a common bus line 24 to which consumers of electric power 25 are connected (individual manual welding stations). The device also includes a switch-off logic element 26

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pulse counter clock generator, pulse clock pulse generator 27 and logic switch element 28 of the logic unit.

The input amplifier 1 is connected by its input to the shunt 13 of the first power supply source 14 of the welding current, and the output to the inputs of the threshold elements of the upper 2 and lower 3 values of the switching current and the switching off element 10 of the first power supply, the outputs of which are connected to the inputs of the logic unit 4 connected by the outputs through the block 8 electronic relays to the power supply sources 15-23 of the welding current, as well as to the D / A converter 7, the output of which is connected to the threshold element 3 of the lower switching current value. Element 9 of switching on the first source with its input is connected to the welding busbar 24, and the output together with the output of element 10 of turning off the first source through an electronic relay 11 to the first source 14 of the welding current. Element -26 of the on-off logic of the pulse generator of the clock generator is connected by its input to the outputs of element 3 of the lower switching current and pulse counter 27, the clock generator, and output to the input of the counter, the output of which is connected to the input of logic switching logic element 28, and its output is connected to the input of a clock generator, the output of which is connected to the inputs of a pulse counter of a clock generator and a logic unit.

The device works as follows.

The power switch 12 turns on the power supply element 12 of the installation of the logic unit to the zero state automatically converts the logic unit 4 to such a state that all its outputs do not have a turn-on signal for the welding current supply sources. The threshold elements 2 and 3 are set to a position where the control unit of the logic unit 4 is absent at the output of the element 2 of the upper switching current, and the control signal is present at the output of the element 3 of the lower switching current.

Before the welding circuit is closed, i.e. when the welding stations are not working and the shop bus duct is not loaded, all sources of welding current are turned off. In this case, the switching off element 10 does not work, i.e. there is no signal from the shunt 13 of the first source 14, and through the switching on element 9 to the welding busbar 24 a low voltage is supplied from the power supply unit 12.

When the welding circuit is closed by the electricity consumers 25, the element 9 is turned on for switching on the first source and through the electronic relay 11 of this source

includes it. At the same time, through the shunt 13 of the first power source 14 of the welding current, a welding load current begins to flow. The signal from the shunt 13 is fed to

the input amplifier 1 and further to the element 10 of turning off the first source, which maintains the electronic relay 11 in the on state until the welding current flows through the shunt 13. The switching element 9 is closed by the welding voltage of the first power source. In the future, at any load on the common busline, the maintenance in the switched on state of the first source 14 is provided only for

account item 10 off.

From the output of the input amplifier 1, a signal proportional to the welding load is fed to the inputs of the threshold elements of the upper 2 and lower 3 values of the switching current.

If the magnitude of the signal removed from amplifier 1 at the input of threshold elements 2 and 3 exceeds the load current rating of the first source 14, then threshold element 2 of the upper switching current is triggered. The clock generator 5 at certain time intervals (1-4 s) continuously sends pulses to logic block 4, the outputs of which are connected to the inputs of block 8 electronic relays. When a signal is received from the output of element 2 to the input of logic unit 4, a command is issued to allow the passage of pulses from the clock generator 5 to logic unit 4, which is transferred to a state that provides connection via the unit 8 of electronic relays of the second source 15.

5 As a result, the load rate of the first source is reduced.

If, after connecting the second power supply 15, the established load level of the first power supply exceeds its rated current, then the threshold element 2 of the upper switching current does not return to its original state, but with the next pulse from the clock generator 5 through the logic unit and the corresponding cell 8 electronic pe connected the third power source 16 of the welding current, after which the load level of the first power source was again reduced.

If, after starting the third power supply, the load of the first power supply again exceeds the rated current of the first power supply, then the next pulse from the clock generator 5 connects the subsequent power sources, etc., until the load power of the first power supply source will be below the value of its rated load current. In this case, the threshold element 2 of the upper switching current value returns to the initial state and the input of logic unit 4 receives from the element 2 a prohibition signal for the passage of pulses from the clock generator 5, thereby terminating the connection to the welding power line of the next power sources. Upon further connection to the busbar of the electricity consumers 25, the order of connecting the welding current power sources is repeated according to the described scheme.

When reducing the load on the busbar, the device operates as follows.

When reducing the value of the welding current in the busline 24, the element 3 of the lower switching current value receives two signals: the first from the shunt 13 through the input amplifier 1 proportional to the load in the busline, the second from the digital analogue converter 7, which receives signals from the outputs of the logic unit 4, corresponding to the number of connected power sources. The digital-to-analog converter 7 downwards changes the threshold of the element 3 for the lower switching current value after each change in the state of the logic unit 4, preparing for switching off the welding sources.

This is due to the fact that when parallel-side sources of welding current are operated on a busbar, when sources are switched off sequentially, the signal on the shunt of the first source changes in steps, and the lower switching current value should be higher, the more sources connected to the busbar. These two signals are compared with each other. If the signal from the shunt 13 is less than the signal from the digital-to-analog converter 7, then element 3 changes the order of logic unit 4 to reverse and simultaneously switches the counter 27 of the clock of the generator oscillator through logic element 26 and the pulse 27 comes from its output. to the input of the switching logic element 28 of the logic unit 4. As a result, the output from the logic element 28 is allowed to pass a pulse from the clock generator 5 to the input of the logical unit 4, which switches to the previous state, causing it thus through the cell of the electronic relay unit 8 disabling the previous source. This increases the load on all remaining connected power sources of the welding machine.

current The pulse counter 27, when filled, is zeroed through logic element 26, and if the load level of the first source 14 is less than the lower switching current value of the remaining connected sources, the shutdown process is repeated as described until the load level of the first source is set occupies a position between the upper and lower switching values. In this case, the counter 27 of the pulses of the clock generator 5 is nullified, since the element 26 of the on / off logic of the counter of 27 pulses closes the permissive input of the pulse account due to the absence

signal from the threshold element 3 of the lower value of the switching current. With a further change to a higher or lower loading side of the welding busbar, the required number of welding power supply sources is automatically connected or disconnected.

Compared with the basic object of the prototype, the device will increase the service life of welding current sources by eliminating the frequent switching on and off of sources with a sharp change in the load current in the welding busbar.

Claims (1)

Invention Formula Device for controlling the operation of a group of welding current sources according to ed. St. No. 1328104, characterized in that, in order to increase the service life of welding current sources by eliminating frequent switching on and off of sources with abrupt changes in load current in the welding bus 5 wire, the device is additionally equipped with a logic switch on and off pulse counter clock generator and the logic switching element of the logic unit, while the logic switching element of the pulse counter of the clock generator is connected to the outputs with its input the element of the lower value of the switching current and the pulse generator of the clock generator, and the output is connected to the input of the counter whose output is connected to the input of the switching logic element of the logic unit, and its output is connected to the input of the clock generator whose output is connected to the inputs of the pulse generator of the clock generator and logical block.