SU1719169A1 - Welderъs protection device - Google Patents

Abstract

The invention relates to devices for reducing the no-load voltage of welding transformers used for manual arc welding. The purpose of the invention is to increase the labor productivity of the welder by reducing the waste of time associated with the false disconnection of the protective switch and re-enabling it manually while maintaining high sensitivity. The device is provided with a locking element, the output of which is associated with a power unit, a memory unit, an account identifier, a dynamic communication element and a delay element. When the welding circuit is closed, a small enough current flows through it to turn on the power supply unit for full voltage. At the output of the power supply unit, a full idle voltage of the welding-current source appears, an arc is excited, and a welding current flows through the welding circuit. 2 Il. J

Description

The invention relates to a welding technique, in particular, to devices for reducing the no-load voltage of welding transformers used for manual arc welding.

A no-load voltage limiter for a welding transformer is known, comprising a welding arc power supply unit, a welding circuit, a current sensor connected to the power supply unit, a dynamic communication element.

A disadvantage of the known limiter is its low electrical safety.

due to the lack of a power supply control circuit that shuts it off when the operating switch or other elements break down, as well as the device has been turned on falsely when the insulation circuit of the welding circuit is low.

A no-load voltage-reducing device is known, comprising a welding arc power supply unit, a welding circuit, current and voltage sensors associated with a power supply unit, logic plug, connected to the outputs of a voltage and current sensor, protection timer connected to the output of the unit logic.

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ABOUT

The drawback of the device is the low productivity of the welder, which is due to the time spent on restoring the power supply circuit of the welding arc in case of false disconnections of the power supply unit associated with. high sensitivity of the circuit to the contact resistance of the electrode part. When a low sensitivity is set, false disconnections of the protection switch decrease, but at the same time the reliability of the arc excitation decreases, which leads to an increase in the psychophysiological load on the welder and he gets tired more quickly.

Closest to the present invention is a device for reducing the no-load voltage of a welding arc power source comprising a welding arc power supply unit, a welding circuit, current sensors and voltages associated with a power supply unit, a logic unit with two inputs, one of which is connected to current sensor, to another - voltage sensor output, protection timer connected to the output of the logic block.

The known device for reducing the no-load voltage of the welding arc power source reduces the welder’s labor productivity, which is simply due to the time spent on detecting the fact that the welding arc power source was disconnected during the transition from the place of work to the power supply unit and the transition in the opposite direction. The number of trips increases with sensitivity and can reach 12-15 trips per shift, depending on operating conditions. At the same time, an increase in sensitivity is necessary to increase the reliability of the excitation of the arc and, accordingly, to increase labor productivity. Frequent false disconnections reduce sensitivities to zero. To eliminate such blackouts, it is necessary to reduce the sensitivity, i.e. reduce the reliability of the initiation of the arc and, accordingly, labor productivity.

The purpose of the invention is to increase the labor productivity of the welder by reducing the overhead of time associated with the false disconnection of the protection switch and its re-activation, by hand, while maintaining high sensitivity.

. The goal is achieved by the fact that a device containing a power unit for a welding arc, a welding circuit, current and voltage sensors associated with a litany unit, a logic unit with two inputs, one of which is connected to a current sensor output, to another voltage protection timer connected to the output

logic block, additionally a blocking element, the output of which is connected with the power unit of the welding arc, a memory block with S- and R-inputs, an automatic restart timer (timer

AR), pulse counter with C- and R-inputs, account identifier with inputs U and N, a dynamic communication element and a delay element whose input and S input of the memory unit are connected to the output of the protection timer, the output of the memory unit associated with the inputs the timer of the AR and the blocking element, the output of the timer of the AR and connected to the C output of the pulse counter and the R input of the memory unit, the output of the pulse counter connected to the input AND

the account identifier, the inputs of the auto-recloser timer, the dynamic input element and the input N of the account identifier are connected to the output of the current sensor, the outputs of the delay element and the account identifier are connected to the power unit of the welding arc.

Figure 1 shows the functional diagram of the welder protection device; figure 2 - diagram of the timer protection and the delay element.

The welder's protection device consists of a power supply unit 1 for the welding arc, a welding circuit 2, a current sensor 3 and a voltage sensor 4 associated with the power supply unit 1,

logic block 5 with two inputs, to one of the outputs of which the output of current sensor 3 is connected, to another - output of voltage sensor 4, protection timer 6 connected to output of logic block 5, interlocking element 7, the output of which is connected to power supply unit 1 , block 8 of memory with S- and R-inputs, timer 9 AR with two inputs, counter 10 pulses with C- and R-inputs, account identifier 11 with inputs U and N, element 12

dynamic communication vt of the delay element 13, the input of which and the S input of the memory block 8 are connected to the output of the protection timer b, the output 8 of the memory block is connected to one of the inputs of the 9 AR timer 9 and the input of the locking element 7, the output of the AR 9 timer is connected To the C input of the pulse counter 10 and the R input of the memory block 8, the output of the pulse counter 10 is connected to the U input of the account identifier 11, the second of the timer outputs

9 AR, the input of the dynamic coupling element 12 and the input of the account identifier 11 are connected to the output of the current sensor 3, the outputs of the delay element 13 and the account identifier 11 are connected to the power supply unit T of the welding arc.

Welding arc power unit 1 is designed to turn on and off the welding arc power during emergency and operating modes, provide low voltage at the output in standby mode, turn on the full voltage when the arc is energized, maintain full voltage after an arc break for a time up to 1 s and a decrease in the output voltage in the absence of welding, disconnecting the power supply unit 1 from the network when it receives a signal to disconnect from the external protection unit.

The welding circuit is intended for supplying electrical energy from the power supply unit 1 to the welding site and consists of direct and return wires, the electrode holder.

Current sensor 3 is designed to generate a signal when a current of more than 7-8 A appears in welding circuit 2 and can be made as a current transformer connected to the communication circuit of power supply unit 1 with welding circuit 2, to the secondary winding of which a relay element ( relay winding), or a semiconductor relay element (as in the security apparatus of a welder. Type ABS-1, elements TA, pins c, d, R49, VD 13, R 47.VT 14).

Voltage sensor 4 is designed to generate a signal when voltage at the output of power supply unit 1 is higher than acceptable and can be implemented on a voltage relay adjusted to a certain threshold, or as a semiconductor circuit, as in the ABS-1 (elements R 50-R 58, C 14, C15, VD 14, VD 15, VD17, VD18, VS5, VT15).

The logic unit 5 performs analysis of the signals received at its inputs and, in accordance with the task, generates a signal at its output.

The protection timer 6 is designed to control the time of voltage reduction at the output of power supply unit 1 from full voltage to idle to a low voltage allowed under electrical safety conditions (12 V).

The blocking element 7 is designed to block the operation of the power supply unit 1 and establish a reduced voltage at its output when a signal appears at the output of the blocking element 7. The actual performance of this element depends on the practical implementation of the power supply unit 1 of the welding arc. Element 7 can be made in the form of a relay, the contacts of which are included in the control system of power supply unit 1.

The memory unit 8 is designed to store the signal received at the S input. store the signal and erase it when the signal arrives at the R input and the absence of the 5 signal at the S input.

The timer 9 of the automatic reclosing device is designed to delay the time of the signal received at its input and can be implemented on digital counters.

0 The pulse counter 10 is intended for counting the number of pulses arriving at the C-input and is a typical binary-decimal counter on a microcircuit. K5PIE1.

5 The account identifier 11 is intended to identify the number entered at the input U and produce a signal at its output if the identification has occurred and is a digital null authority or

0 scheme based on the decoder.

Dynamic communication element 12 is designed to create a short pulse at the output when the state of the signal at the input changes and can be made on the basis of an RC circuit or microcircuits.

The delay element 13 is designed to create a short delay for the appearance of a signal at the output after the filing

0 signal to the input necessary to prevent false disconnection of power supply 1 after the protection timer 6 has been triggered and it has started the AR cycle.

Protection timer 6 is performed on the elements.

5 14-17, which are a counting pulse generator 18 and counters 19 and 20.

Element 13 of the delay is made on the logic circuit 2I-NOT connected to the outputs of the SN.STS, counter 20 timer b protection

0 and consists of inverters 21 and 22. Elements 16,17 and 13 are made on a single chip of the K5II / 1AI series, elements 19,20 - on K5NIE1 chips. The output Q4 of counter 20 is the output of timer b protection.

5 Standby idling mode.

The power supply unit 1 of the welding arc is connected to the mains. Welding circuit 2 is open. At the output of the power supply unit 1, a lower voltage is created (no more than 12 V). The signals at the outputs of all elements and units of the device are equal to 0 (except for the element of dynamic communication 12, at the output of which the signal is 1); The setting of the account identifier 11 is N (0) ..

5 Excite arc. When the welding circuit 2 is closed, a small enough current flows through it to turn on the power supply unit 1 to full voltage. At the output of power supply unit 1, a complete idle voltage of the welding source appears.

current, an arc is excited, and a welding current greater than 7-8 A flows through the welding circuit 2. At the output of current sensor 3, signal H appears. At the output of logic block 5, the signal is O. At the same time, the output signal from current sensor 3 is fed to the input timer AR 9, run it; to the input of the account identifier 11, changing its setpoint from N (0) to N (1), as well as to the input of the dynamic coupling element 12, set the counter 10 pulses to O.

Intermittent arc burning. Characteristic for ceiling and vertical welding. It is characterized by repetition of the processes of closing the welding circuit 2, opening the circuit 2 and initiating the arc, a short period of arc burning, breakage and re-excitation. Although the signals at the outputs of voltage sensor 4 and logic block 5 periodically change the signal at the output of protection timer 6 is 0m. With each occurrence of a signal at the output of current sensor 3, the pulse counter 10 is set to O, erasing previously accumulated information. If the conditions are met:

txx tz; (1)

ta N (1) TAPV,

(2)

where txx is the time of existence on the welding circuit 2 of the total idle voltage of the power supply unit 1 after an arc break;

Tz time delay timer protection b;

ta is the time of continuous arc welding;

N (1) - setpoint identifier 11 accounts in the presence of the input N signal

TAPV is the holding time of the recloser 9, then the device can be in such a state of dynamic equilibrium for a long time.

Long arc burning.

It is characteristic for metal surfacing. The operation of the circuit is different from the previous one.

process in that the output signal

logic block 5 does not appear in the process of arc burning. The signal at the output of current sensor 3 exists for a long time, i.e. To avoid a false disconnection of the device, it is necessary to fulfill the conditions (2). At 50 this, the setting N (1) and the time of the LLV are selected. In the way that

N (1) TAPV Ј tM / (3)

where tM is the maximum permissible time of continuous operation of the power source under heating conditions.

For welding transformers with PV - 60% and cycle time T - 5 minutes,.

5 10

15 20 25

thirty

35

40

45

50

55

tM 18.0 s. In this mode, the automatic reclosing timer 9 operates as a ring counter, periodically generating pulses at its output, which are fixed by a counter of 10 pulses.

Since the value of the signal at the output of the pulse counter 10 is less than the setpoint N (1), the signal at the output of identifier 11 does not appear and the device is in a state of dynamic equilibrium

Idling.

In this mode, a signal appears at the output of the voltage sensor 4 and, accordingly, a signal at the output of the logic block 5. Protection Timer 6 starts. At the same time, the timer of the power supply unit 1 with a time delay reduces the voltage in the welding circuit 2. The signal at the output of the voltage sensor 1 disappears, which leads to the disappearance of the signal at the output of the logic unit 5, the protection timer 5 returns to its initial state.

The circuit goes into idle duty mode.

Emergency regimes in which there is a certain danger to welders or maintenance personnel.

Prolonged existence of high voltage on the welding circuit 2.

It may be caused by faults in the power supply unit 1 circuit. In this case, a signal appears at the output of the voltage sensor 4, leading to the appearance of a signal at the output of the logic block 5. The latter includes timer 6 protection. Upon the appearance of a signal at its output, a memory block 8 is turned on, from the output of which the signal is fed to the inputs of the timer AR 9 and the locking element 7. At the same time, the delay element 13 processes its time delay. If the voltage in the welding circuit does not disappear, the signal from the output of the delay element 13 arriving at the input of the power supply unit 1 switches it on. The supply voltage is completely removed from the welding machine.

Prolonged leakage in the welding circuit 2. It may be associated with a decrease in the insulation resistance of the welding circuit 2. In this case, the power supply unit 1 is turned on and supplies full voltage to the welding circuit 2. The timers of power supply 1 and protection 6 itself start by running on time delays. Due to the leakage of current, the power supply unit 1 remains on for a long time, longer than one. Therefore, a signal appears at the output of the protection timer 6, which starts the shutter element 13 and the memory block 8. A signal from the output of the memory block 8 starts the AP B 9 timer and enters the input of the locking element 7, which blocks the operation of the power supply unit 1. In this case, at the output of the power supply unit 1 and in the welding circuit 2 is created. reduced voltage. Sets the auto reclosing mode. As soon as the signal appears at the output of timer 9 of the AR, it changes the state of the counter 10 pulses from 0 to 1. At the same time, the signal from the output of the timer AR 9, arriving at the R input of memory 8, erases the information. The signal at the output of the memory block 8 disappears, unlocks the power supply unit 1 and sets the timer 9 of the auto-recloser to 0. This completes one cycle of the auto-recloser. Further state depends on leakage. If the leak disappears, the device goes into standby mode. If the leakage persists, a repeated AR cycle occurs. With each cycle, the pulse counter 10 changes the signal value at its output by one.

The setting N (0) of the account identifier 11 is chosen from

MPV + 2 N (0) NAHB (3)

where N AR is the permissible number of automatic re-inclusions.

Based on experience, it is determined that MAPV 5.

As soon as the signal at the output of the pulse counter 10 is equal to the setpoint N (0), a signal appears at the output of the count identifier 11, which disconnects the power supply unit 1 from the network. In the welding circuit 2, the voltage completely disappears.

If the leakage in welding circuit 2 is caused by a low resistance of a person, the forced decrease of voltage in the welding circuit for the cycle time of the automatic reclosure is determined by the timer 9 of automatic reclosing, provides conditions for self-relieving the person from the welding circuit, reducing the consequences of electrical injury.

At the expense of AR, the welder does not need to waste time on switching on the power supply unit 1, which ensures an increase in labor productivity. The AR effect is greater, the higher the sensitivity of the device (the more often false outages).

When the welding process occurs, the pulse counter 10 through the dynamic coupling element 12 from the current sensor 3 is set to O, which prevents the recording of AR cycles during welding.

Short circuit welding circuit. This mode is characterized by the fact that the arc does not occur. The forward and return wires are connected directly to each other through a conductive object.

In this mode, the welding circuit is supplied with the full supply voltage from the power source 1. At the output of current sensor 3 for a long time, signal 1 exists. At output 5 of sensor 4 of voltage, there is no signal. The signal at the output of block 5 logic is also missing. The pulse counter 10 from the current sensor 3 through the dynamic communication element 12 is set to O, the setting of the count identifier 11 is changed from N (0) to N (1). The output signal from the current sensor 3 starts the timer 9 AR. From this moment begins the control of the duration of the welding current. Since timer 9 of the auto-recloser works as

5 ring counter, then with each change of the signal at its output, the pulse counter 10 increases by one the value of the signal at its output. As soon as the signal at the output of the counter 10 pulses becomes equal

0 setting N (1) of the account identifier 11, a signal appears at the output of the account identifier 11 and power supply unit 1 is disconnected from the network. This prevents ignition of the insulation of the welding wires or of the power source itself during long-term closure of the welding circuit.

Logic elements 16 and 17 and resistors 14 and 15 are a counting pulse generator controlled by a signal from the logic unit 5. Counters 19 and 20 count incoming pulses from the generator C1 and C2 from the generator of counting pulses 18 only if signal R is present at the R inputs. When signal O arrives at the R inputs, the state of the signals at the counter outputs corresponds to the signal O, t. -e on exits,.

Upon receipt from block 5 of the logic signal 1, the counters 19 and 20 (Fig.2) begin

0 countdown. The information on the outputs Q of the counter 20 is increased. There comes a moment when the signal at the output Q4 of the counter 20 changes from 1 to O, which corresponds to the appearance of the signal at the output of the timer 6

5 protection (figure 2). The signals at the outputs of counter 20,, therefore, the signal at the output of the delay element remains the same. After some time the signals and. which leads to a change in the signal at the output of the delay element 13 from 0 to 1, which is perceived by power supply 1 as a signal to turn off. In this case, the time delay of the delay element 13 is provided by the internal clock of the counters 19 and 20. The delay element 13 acts as an identifier of the number of pulses received at the counting inputs C1 and C2 of the counter 19 from the generator 10 of counting pulses.

The effectiveness of the proposed technical solution was tested on a model of a welder’s protection device having a sensitivity of 300 Ohms, switching speed of 0.0046 s, operating timer of the control unit of the operating switch 0.75 s, holding timer of the protective timer 0.8 s, delaying element delay time 0 , 08 s, the number of automatic restarts 3, the exposure time of the automatic reclosing timer US.

Observations showed that in some shifts the number of false shutdowns of the device without ARA reached 14-15 times a shift, with ARA it ranged from 2 to 5. In addition, the time required for reclosing was saved, i.e. labor productivity of the welder is increased and the welder is reliably protected, in particular, during long-term closure of the welding circuit.

Claims (1)

Invention Formula Welder protection device containing welding arc power supply unit, welding circuit, current and voltage sensors connected to the power supply unit, logic unit with two inputs, one of which is connected to the current sensor output, the other is voltage sensor output, protection timer connected to the output of the logic block, r 0 five 0 five 0 kicking the fact that, in order to increase labor productivity by reducing the unproductive time spent on turning on the power supply during false shutdowns due to high sensitivity, a blocking element whose output is connected to the power supply is inserted into it, a memory block with two inputs , two-input auto-reclosing timer, two-input pulse counter, two-input counting identifier, dynamic communication element and delay element, the input of which and the first input of the memory unit are connected The output of the protection timer, the output of the memory unit are connected to the first input of the auto-recloser timer and the input of the blocking element, the output of the automatic reclosing timer is connected to the first input of the pulse counter and the second input of the memory unit, the output of the pulse counter is connected to the first input of the identifier account, the second input of the automatic switch-on timer, the input of the dynamic communication element and the second input of the account identifier are connected to the output of the current sensor, the outputs of the delay element and the identification ora account associated with the arc power supply. F. From 5 FIG. I