CN207787929U - A kind of unloaded automatic power-off device of A.C. welder - Google Patents

Abstract

The utility model discloses a kind of unloaded automatic power-off devices of A.C. welder.It includes capacitance C1, resistance R2, intermediate relay KR and A.C. contactor KA, the first output end of power switch S1, the coil of A.C. contactor KA, the normally-closed contact switch SKR1 of intermediate relay KR, the second output terminal of power switch S1 is sequentially connected in series, the first output end of power switch S1, the normally opened contact switch SKA1 of A.C. contactor KA, the primary coil of transformer TV1, the second output terminal of power switch S1 is sequentially connected in series, capacitance C1 is in parallel with the normally opened contact switch SKA1 of A.C. contactor KA, the first secondary coil of transformer TV1, resistance R2, the coil of intermediate relay KR is sequentially connected in series into a circuit.The utility model can automatically cut off a main power source in A.C. welder zero load, reduce unnecessary no-load loss, save electric energy, it is ensured that equipment and operating personnel's safety.

Description

A kind of unloaded automatic power-off device of A.C. welder

Technical field

The utility model is related to ac spot welding machine control technology fields more particularly to a kind of zero load of A.C. welder to stop automatically Electric installation.

Background technology

Existing regular alternating current electricity（Arc）Main power source of welding machine cannot be automatically cut off after welder, at this time at welding machine In light condition, certainly will there are reactive energy loss, especially large capacity welding machine.Such as：The projection welder of automobile industry sealing wire hangs Hanging mash welder etc., welding machine quantity is big, and weld interval is short, and idle time is long, and reactive energy loss is especially serious；When welding machine zero load Main power source of welding machine cannot be automatically cut off, first and second winding of welding machine remains electrification, and certainly will influence welding machine uses the longevity Life, while there are security risks to operating personnel.

Invention content

The purpose of the utility model is to overcome existing A.C. welders cannot automatically cut off welding machine once main electricity in zero load Source, reactive loss is serious in the unloaded state for welding machine, influences welding machine service life, there is technical issues that, provides A kind of unloaded automatic power-off device of A.C. welder, can automatically cut off a main power source in A.C. welder zero load, Unnecessary no-load loss is reduced, electric energy is saved, it is ensured that equipment and operating personnel's safety.

To solve the above-mentioned problems, the utility model is achieved using following technical scheme：

A kind of unloaded automatic power-off device of A.C. welder of the utility model, A.C. welder include power switch S1 and Two input terminals of transformer TV1, power switch S1 are electrically connected with the both ends of AC power respectively, unloaded automatic power-off device packet Include capacitance C1, resistance R2, intermediate relay KR and A.C. contactor KA, the first output end, the A.C. contactor of power switch S1 The coil of KA, the normally-closed contact switch SKR1 of intermediate relay KR, power switch S1 second output terminal be sequentially connected in series, power supply is opened Close the first output end, the normally opened contact switch SKA1 of A.C. contactor KA, the primary coil of transformer TV1, the power switch of S1 The second output terminal of S1 is sequentially connected in series, and capacitance C1 is in parallel with the normally opened contact switch SKA1 of A.C. contactor KA, transformer TV1's First secondary coil, resistance R2, intermediate relay KR coil be sequentially connected in series into a circuit.

In the technical scheme, when work, the first secondary coil both ends of transformer TV1 respectively with soldering turret and welding workpiece Connection.Power turn-on switch S1, normally opened contact switch SKA1 are off, and alternating current is added in transformer by capacitance C1 First secondary coil of the primary coil of TV1, transformer TV1 generates induced voltage, at this point, the coil of intermediate relay KR is logical The normally-closed contact switch SKR1 of electricity, intermediate relay KR is disconnected, and the coil blackout of A.C. contactor KA, A.C. contactor KA's is normal It opens contact switch SKA1 to be off, main power source of A.C. welder is not switched on, and electric energy loss is small.

When A.C. welder welds, soldering turret and welding workpiece overlap joint short circuit, intermediate relay KR coil under-voltages are intermediate The normally-closed contact switch SKR1 of relay KR is closed, and the coil of A.C. contactor KA is powered, the normally opened contact of A.C. contactor KA Switch SKA1 is closed, and main power source of A.C. welder is connected, normal weld.

When A.C. welder stops welding zero load, soldering turret and welding workpiece do not contact, intermediate relay KR coils both ends Voltage increases, and the normally-closed contact switch SKR1 of intermediate relay KR is disconnected, the coil blackout of A.C. contactor KA, A.C. contactor The normally opened contact switch SKA1 of KA is off, and main power source of A.C. welder is not switched on, and electric energy loss is small.

Preferably, the unloaded automatic power-off device of a kind of A.C. welder further includes fuse FU, fuse FU, The series circuit of capacitance C1 compositions is in parallel with the normally opened contact switch SKA1 of A.C. contactor KA.Fuse FU protection circuit peaces Entirely.

Preferably, the unloaded automatic power-off device of a kind of A.C. welder further includes diode V1, resistance R1 and electricity Hold C2, first secondary coil one end of transformer TV1 is electrically connected with the one end resistance R2, the resistance R2 other ends and diode V1 anodes Electrical connection, diode V1 cathodes are electrically connected with coil one end of the one end capacitance C2, intermediate relay KR, the line of intermediate relay KR The circle other end is electrically connected with the one end normally-closed contact switch SKA3, the one end resistance R1 of the capacitance C2 other ends, A.C. contactor KA, electricity The resistance R1 other ends are electrically connected with one end normally opened contact switch SKA4 of A.C. contactor KA, and the normally opened contact of A.C. contactor KA is opened It closes the SKA4 other ends and the normally-closed contact switch SKA3 other ends, the first secondary coil of transformer TV1 of A.C. contactor KA is another One end is electrically connected.

When A.C. welder welds, the coil of A.C. contactor KA is powered, the normally opened contact switch of A.C. contactor KA SKA4 is closed, and normally-closed contact switch SKA3 is disconnected, and the first secondary coil voltages of transformer TV1 are opened by resistance R1, normally opened contact Close the coil both ends that SKA4 is added in intermediate relay KR.When A.C. welder stops welding, the coil of A.C. contactor KA is disconnected The normally opened contact switch SKA4 of electricity, A.C. contactor KA is disconnected, and normally-closed contact switch SKA3 is closed, first grade of transformer TV1 Coil voltage is added in the coil both ends of intermediate relay KR by resistance R2, normally-closed contact switch SKA3.Resistance R1, resistance R2 are For adjustable resistance.

Preferably, the unloaded automatic power-off device of a kind of A.C. welder further includes indicator light circuit, indicator light electricity Road includes transformer TV2, indicator light HL1 and indicator light HL2, the primary coil both ends of transformer TV2 respectively with power switch S1 Two output ends electrical connection, secondary coil one end and the one end indicator light HL1, the one end indicator light HL2 of transformer TV2 are electrically connected It connects, the indicator light HL1 other ends are another by the normally opened contact switch SKA6 and the secondary coil of transformer TV2 of A.C. contactor KA End electrical connection, the secondary wire that the indicator light HL2 other ends pass through the normally-closed contact switch SKA7 and transformer TV2 of A.C. contactor KA Enclose other end electrical connection.When A.C. welder welds, indicator light HL1 is lighted；When A.C. welder stops welding, indicator light HL2 is lighted.

Preferably, a kind of unloaded automatic power-off device of A.C. welder further includes delay circuit, delay circuit Including rectifier bridge VC, switch S2, resistance R3, resistance R4, resistance R7, resistance R8, capacitance C3, metal-oxide-semiconductor Q and time relay K, become The second subprime coil both ends of depressor TV1 are electrically connected with two input terminals of rectifier bridge VC respectively, the first output of rectifier bridge VC End is electrically connected with the one end resistance R3, the one end resistance R4, and the resistance R4 other ends are electrically connected with the drain electrode of metal-oxide-semiconductor Q, the resistance R3 other ends It is electrically connected with the one end resistance R8, the one end switch S2, the resistance R8 other ends and the switch S2 other ends, the one end resistance R7, capacitance C3 mono- The grid electrical connection at end, metal-oxide-semiconductor Q, the resistance R7 other ends are electrically connected with one end normally-closed contact switch SKR3 of intermediate relay KR, The capacitance C3 other ends are electrically connected with the normally-closed contact switch SKR3 other ends of intermediate relay KR, the one end normally opened contact switch SKR2 Connect, the normally opened contact switch SKR2 other ends of intermediate relay KR and time relay K coils one end, rectifier bridge VC it is second defeated Outlet is electrically connected, and the time relay K coils other end is electrically connected with the source electrode of metal-oxide-semiconductor Q, and the normally-closed contact of time relay K is opened It closes SK1 to be serially connected between the coil of A.C. contactor KA and the normally-closed contact switch SKR1 of intermediate relay KR, A.C. contactor The normally opened contact switch SKA5 of KA is in parallel with the normally-closed contact switch SKR1 of intermediate relay KR.

When A.C. welder welds, the coil of A.C. contactor KA is powered, the normally opened contact switch of A.C. contactor KA SKA5 is closed.When A.C. welder stops welding, the coil of intermediate relay KR is powered, the normally-closed contact of intermediate relay KR Switch SKR1 is disconnected, and normally opened contact switch SKR2 is closed, and normally-closed contact switch SKR3 is disconnected, still due to normally opened contact switch SKA5 So be closed, the coil of A.C. contactor KA do not power off, and A.C. welder be in light condition, at this point, metal-oxide-semiconductor Q is connected, the time after The coil of electric appliance K, which is powered, starts timing.If A.C. welder welds again in the delay time of time relay K, in Between relay KR coil blackout, the normally-closed contact switch SKR1 of intermediate relay KR is closed, and normally opened contact switch SKR2 is disconnected, Normally-closed contact switch SKR3 is closed, and capacitance C3 is not turned on through normally-closed contact switch SKR3, resistance R7 repid discharges, metal-oxide-semiconductor Q, when Between relay K coil blackout, for next time conducting prepare, make power supply when welding that will not interrupt.If A.C. welder exists It is not welded again in the delay time of time relay K, when delay time reaches, the normally-closed contact of time relay K is opened It closes SK1 to disconnect, the coil blackout of A.C. contactor KA, the normally opened contact switch SKA5 disconnections of A.C. contactor KA, normally opened contact Switch SKA1 is disconnected, and main power source of A.C. welder is not switched on, and electric energy loss is small.A.C. welder can be delayed shutdown, Using more convenient.

Preferably, delay circuit further includes capacitance C5, the coils from parallel connection of coils of capacitance C5 and time relay K.

Preferably, delay circuit further includes voltage-stabiliser tube V6, the first output end electricity of voltage-stabiliser tube V6 cathodes and rectifier bridge VC Connection, voltage-stabiliser tube V6 anodes are electrically connected with the second output terminal of rectifier bridge VC.

Preferably, the unloaded automatic power-off device of a kind of A.C. welder further includes filter circuit, filter circuit packet Capacitance C4, resistance R5 and resistance R6 are included, the one end capacitance C4 is electrically connected with the first output end of the one end resistance R6, rectifier bridge VC, electricity The resistance R6 other ends are electrically connected with the one end resistance R5, voltage-stabiliser tube V6 cathodes, the resistance R5 other ends and the capacitance C4 other ends, rectifier bridge VC Second output terminal electrical connection.

Preferably, the normally opened contact switch of the normally opened contact switch SKA2 and A.C. contactor KA of A.C. contactor KA SKA1 is in parallel.

The utility model has the beneficial effects that：A main power source can be automatically cut off in A.C. welder zero load, reduced Unnecessary no-load loss saves electric energy, it is ensured that equipment and operating personnel's safety.

Description of the drawings

Fig. 1 is a kind of circuit diagram of the utility model.

Specific implementation mode

Below with reference to the embodiments and with reference to the accompanying drawing the technical solutions of the present invention will be further described.

Embodiment 1：The unloaded automatic power-off device of a kind of A.C. welder of the present embodiment, as shown in Figure 1, A.C. welder Including power switch S1 and transformer TV1, two input terminals of power switch S1 are electrically connected with the both ends of AC power respectively, empty Be downloaded from dynamic power-off device include capacitance C1, fuse FU, resistance R2, intermediate relay KR, A.C. contactor KA, diode V1, Resistance R1 and capacitance C2, the first output end of power switch S1, the coil of A.C. contactor KA, the normally closed of intermediate relay KR are touched Put switch SKR1, the second output terminal of power switch S1 is sequentially connected in series, the first output end, the A.C. contactor KA of power switch S1 Normally opened contact switch SKA1, the primary coil of transformer TV1, the second output terminal of power switch S1 be sequentially connected in series, fuse FU, the series circuit of capacitance C1 compositions are in parallel with the normally opened contact switch SKA1 of A.C. contactor KA, and A.C. contactor KA's is normal Open that contact switch SKA2 is in parallel with the normally opened contact switch SKA1 of A.C. contactor KA, the first secondary coil one of transformer TV1 End is electrically connected with the one end resistance R2, and the resistance R2 other ends are electrically connected with diode V1 anodes, diode V1 cathodes and capacitance C2 mono- Coil one end electrical connection at end, intermediate relay KR, the coil other end of intermediate relay KR and the capacitance C2 other ends are exchanged and are connect One end normally-closed contact switch SKA3 of tentaculum KA, the electrical connection of the one end resistance R1, the resistance R1 other ends are normal with A.C. contactor KA's The electrical connection of the one end contact switch SKA4 is opened, the normally opened contact switch SKA4 other ends of A.C. contactor KA are with A.C. contactor KA's The first secondary coil other end electrical connection of the normally-closed contact switch SKA3 other ends, transformer TV1.

When work, the first secondary coil both ends of transformer TV1 are connect with soldering turret and welding workpiece respectively.Power turn-on is opened S1 is closed, normally opened contact switch SKA1, SKA2 is off, and 380V alternating currents are added in the first of transformer TV1 by capacitance C1 Grade coil, fuse FU protect circuit safety, the first secondary coil of transformer TV1 to generate the induced voltage of 20V ~ 40V, this When, the coil of intermediate relay KR is powered, and the normally-closed contact switch SKR1 of intermediate relay KR is disconnected, the line of A.C. contactor KA Circle power-off, normally opened contact switch SKA1, SKA2 of A.C. contactor KA are off, and main power source of A.C. welder does not have There are connection, electric energy loss small.

When A.C. welder welds, soldering turret and welding workpiece overlap joint short circuit, intermediate relay KR coil under-voltages are intermediate The normally-closed contact switch SKR1 of relay KR is closed, and the coil of A.C. contactor KA is powered, the normally opened contact of A.C. contactor KA Switch SKA1, SKA2 are closed, and the normally opened contact switch SKA4 of A.C. contactor KA is closed, and normally-closed contact switch SKA3 is disconnected, and is become The first secondary coil voltages of depressor TV1 are added in the coil both ends of intermediate relay KR by resistance R1, normally opened contact switch SKA4, Main power source of A.C. welder is connected, normal weld.

When A.C. welder stops welding zero load, soldering turret and welding workpiece do not contact, intermediate relay KR coils both ends Voltage increases, and the normally-closed contact switch SKR1 of intermediate relay KR is disconnected, the coil blackout of A.C. contactor KA, A.C. contactor Normally opened contact switch SKA1, SKA2 of KA is off, and the normally opened contact switch SKA4 of A.C. contactor KA is disconnected, normally closed Contact switch SKA3 is closed, and the first secondary coil voltages of transformer TV1 are added in centre by resistance R2, normally-closed contact switch SKA3 The coil both ends of relay KR, main power source of A.C. welder are not switched on, and electric energy loss is small.Resistance R1, resistance R2 are Adjustable resistance.

Unloaded automatic power-off device further includes indicator light circuit, indicator light circuit include transformer TV2, indicator light HL1 and The primary coil both ends of indicator light HL2, transformer TV2 are electrically connected with two output ends of power switch S1 respectively, transformer TV2 Secondary coil one end be electrically connected with the one end indicator light HL1, the one end indicator light HL2, the indicator light HL1 other ends pass through ac contactor The secondary coil other end of the normally opened contact switch SKA6 and transformer TV2 of device KA are electrically connected, and the indicator light HL2 other ends pass through friendship The secondary coil other end of the normally-closed contact switch SKA7 and transformer TV2 of stream contactor KA are electrically connected.When A.C. welder welds When connecing, indicator light HL1 is lighted；When A.C. welder stops welding, indicator light HL2 is lighted.

Embodiment 2：The unloaded automatic power-off device of a kind of A.C. welder of the present embodiment, as shown in Figure 1, further including delay Circuit and filter circuit, remaining structure are same as Example 1.

Delay circuit includes rectifier bridge VC, switch S2, resistance R3, resistance R4, resistance R7, resistance R8, capacitance C3, capacitance C5, voltage-stabiliser tube V6, metal-oxide-semiconductor Q and time relay K, filter circuit include capacitance C4, resistance R5 and resistance R6.Transformer TV1's Second subprime coil both ends are electrically connected with two input terminals of rectifier bridge VC respectively, the first output end and the resistance R3 of rectifier bridge VC One end, the electrical connection of the one end resistance R4, the resistance R4 other ends are electrically connected with the drain electrode of metal-oxide-semiconductor Q, the resistance R3 other ends and resistance R8 mono- End, the electrical connection of the one end switch S2, the resistance R8 other ends and the switch S2 other ends, the one end resistance R7, the one end capacitance C3, metal-oxide-semiconductor Q Grid is electrically connected, and the resistance R7 other ends are electrically connected with one end normally-closed contact switch SKR3 of intermediate relay KR, and capacitance C3 is another End is electrically connected with the normally-closed contact switch SKR3 other ends of intermediate relay KR, the one end normally opened contact switch SKR2, intermediate relay The normally opened contact switch SKR2 other ends of device KR are electrically connected with the second output terminal of time relay K coils one end, rectifier bridge VC, The time relay K coils other end is electrically connected with the source electrode of metal-oxide-semiconductor Q, the coils from parallel connection of coils of capacitance C5 and time relay K, the time The normally-closed contact for the coil and intermediate relay KR that the normally-closed contact switch SK1 of relay K is serially connected with A.C. contactor KA switchs Between SKR1, the normally opened contact switch SKA5 of A.C. contactor KA is in parallel with the normally-closed contact switch SKR1 of intermediate relay KR, The one end capacitance C4 is electrically connected with the first output end of the one end resistance R6, rectifier bridge VC, the resistance R6 other ends and the one end resistance R5, steady Pressure pipe V6 cathodes are electrically connected, the second output terminal of voltage-stabiliser tube V6 anodes and the resistance R5 other ends, the capacitance C4 other ends, rectifier bridge VC Electrical connection.

When A.C. welder welds, the coil of A.C. contactor KA is powered, the normally opened contact switch of A.C. contactor KA SKA5 is closed.When A.C. welder stops welding, the coil of intermediate relay KR is powered, the normally-closed contact of intermediate relay KR Switch SKR1 is disconnected, and normally opened contact switch SKR2 is closed, and normally-closed contact switch SKR3 is disconnected, still due to normally opened contact switch SKA5 So be closed, the coil of A.C. contactor KA do not power off, and A.C. welder be in light condition, at this point, metal-oxide-semiconductor Q is connected, the time after The coil of electric appliance K, which is powered, starts timing.If A.C. welder welds again in the delay time of time relay K, in Between relay KR coil blackout, the normally-closed contact switch SKR1 of intermediate relay KR is closed, and normally opened contact switch SKR2 is disconnected, Normally-closed contact switch SKR3 is closed, and capacitance C3 is not turned on through normally-closed contact switch SKR3, resistance R7 repid discharges, metal-oxide-semiconductor Q, when Between relay K coil blackout, for next time conducting prepare, make power supply when welding that will not interrupt.If A.C. welder exists It is not welded again in the delay time of time relay K, when delay time reaches, the normally-closed contact of time relay K is opened It closes SK1 to disconnect, the coil blackout of A.C. contactor KA, the normally opened contact switch SKA5 disconnections of A.C. contactor KA, normally opened contact Switch SKA1 is disconnected, and main power source of A.C. welder is not switched on, and electric energy loss is small.A.C. welder can be delayed shutdown, Using more convenient.

Claims (9)

1. a kind of unloaded automatic power-off device of A.C. welder, the A.C. welder includes power switch S1 and transformer TV1, Two input terminals of power switch S1 are electrically connected with the both ends of AC power respectively, it is characterised in that：Including capacitance C1, resistance R2, intermediate relay KR and A.C. contactor KA, the first output end of power switch S1, the coil of A.C. contactor KA, centre The normally-closed contact switch SKR1 of relay KR, the second output terminal of power switch S1 are sequentially connected in series, and the first of power switch S1 is defeated Second output of outlet, the normally opened contact switch SKA1 of A.C. contactor KA, the primary coil of transformer TV1, power switch S1 End is sequentially connected in series, and capacitance C1 is in parallel with the normally opened contact switch SKA1 of A.C. contactor KA, the first secondary wire of transformer TV1 Circle, resistance R2, intermediate relay KR coil be sequentially connected in series into a circuit.

2. the unloaded automatic power-off device of a kind of A.C. welder according to claim 1, it is characterised in that：Further include melting Disconnected device FU, fuse FU, the series circuit of capacitance C1 compositions are in parallel with the normally opened contact switch SKA1 of A.C. contactor KA.

3. the unloaded automatic power-off device of a kind of A.C. welder according to claim 1, it is characterised in that：Further include two First secondary coil one end of pole pipe V1, resistance R1 and capacitance C2, transformer TV1 are electrically connected with the one end resistance R2, and resistance R2 is another One end is electrically connected with diode V1 anodes, and diode V1 cathodes and coil one end of the one end capacitance C2, intermediate relay KR are electrically connected Connect, the coil other end of intermediate relay KR and the capacitance C2 other ends, A.C. contactor KA the one end normally-closed contact switch SKA3, The one end resistance R1 is electrically connected, and the resistance R1 other ends are electrically connected with one end normally opened contact switch SKA4 of A.C. contactor KA, is exchanged The normally opened contact switch SKA4 other ends of contactor KA and the normally-closed contact switch SKA3 other ends, the transformer of A.C. contactor KA The first secondary coil other end of TV1 is electrically connected.

4. the unloaded automatic power-off device of a kind of A.C. welder according to claim 1 or 2 or 3, it is characterised in that：Also Including indicator light circuit, indicator light circuit includes transformer TV2, indicator light HL1 and indicator light HL2, the primary line of transformer TV2 Circle both ends are electrically connected with two output ends of power switch S1 respectively, secondary coil one end and the indicator light HL1 mono- of transformer TV2 End, the electrical connection of the one end indicator light HL2, normally opened contact switch SKA6 and change of the indicator light HL1 other ends by A.C. contactor KA The secondary coil other end of depressor TV2 is electrically connected, and the indicator light HL2 other ends are switched by the normally-closed contact of A.C. contactor KA SKA7 is electrically connected with the secondary coil other end of transformer TV2.

5. the unloaded automatic power-off device of a kind of A.C. welder according to claim 1 or 2 or 3, it is characterised in that：Also Including delay circuit, delay circuit include rectifier bridge VC, switch S2, resistance R3, resistance R4, resistance R7, resistance R8, capacitance C3, The second subprime coil both ends of metal-oxide-semiconductor Q and time relay K, transformer TV1 are electrically connected with two input terminals of rectifier bridge VC respectively It connects, the first output end of rectifier bridge VC is electrically connected with the one end resistance R3, the one end resistance R4, the leakage of the resistance R4 other ends and metal-oxide-semiconductor Q Pole is electrically connected, and the resistance R3 other ends are electrically connected with the one end resistance R8, the one end switch S2, and the resistance R8 other ends and switch S2 are another The grid electrical connection at end, the one end resistance R7, the one end capacitance C3, metal-oxide-semiconductor Q, the resistance R7 other ends are normally closed with intermediate relay KR's The one end contact switch SKR3 is electrically connected, the normally-closed contact switch SKR3 other ends of the capacitance C3 other ends and intermediate relay KR, normal Open the electrical connection of the one end contact switch SKR2, the normally opened contact switch SKR2 other ends and the time relay K lines of intermediate relay KR The second output terminal electrical connection of one end, rectifier bridge VC is enclosed, the time relay K coils other end is electrically connected with the source electrode of metal-oxide-semiconductor Q, The normally-closed contact switch SK1 of time relay K is serially connected with the normally-closed contact of the coil and intermediate relay KR of A.C. contactor KA Between switch SKR1, the normally-closed contact switch SKR1 of the normally opened contact switch SKA5 and intermediate relay KR of A.C. contactor KA are simultaneously Connection.

6. the unloaded automatic power-off device of a kind of A.C. welder according to claim 5, it is characterised in that：Delay circuit Further include capacitance C5, the coils from parallel connection of coils of capacitance C5 and time relay K.

7. the unloaded automatic power-off device of a kind of A.C. welder according to claim 5, it is characterised in that：Delay circuit Further include voltage-stabiliser tube V6, voltage-stabiliser tube V6 cathodes are electrically connected with the first output end of rectifier bridge VC, voltage-stabiliser tube V6 anodes and rectifier bridge The second output terminal of VC is electrically connected.

8. the unloaded automatic power-off device of a kind of A.C. welder according to claim 7, it is characterised in that：It further include filter Wave circuit, filter circuit include capacitance C4, resistance R5 and resistance R6, the one end capacitance C4 and the one end resistance R6, rectifier bridge VC the One output end is electrically connected, and the resistance R6 other ends are electrically connected with the one end resistance R5, voltage-stabiliser tube V6 cathodes, the resistance R5 other ends and capacitance The second output terminal electrical connection of the C4 other ends, rectifier bridge VC.

9. the unloaded automatic power-off device of a kind of A.C. welder according to claim 1 or 2 or 3, it is characterised in that：It hands over The normally opened contact switch SKA2 for flowing contactor KA is in parallel with the normally opened contact switch SKA1 of A.C. contactor KA.