阅读说明：本技术 一种基于接触器的无弧分断电路及工作方法 (Arc-free breaking circuit based on contactor and working method ) 是由 王彩艳 彭玉江 于 2019-11-14 设计创作，主要内容包括：本发明公开了一种基于接触器的无弧分断电路及工作方法,电源的输出端接在电容器上,电容器两端分别接驳与交流接触器主触点并联的双向可控硅的T1极和触发级G极,形成回路,同时,回路中串联有电阻R,以对触发回路电流进行限流及延时。本发明利用可控硅导通时间快而接触器接通时间慢的特点,确保在接触器断开、闭合过程中无电弧产生,既延长了接触器的使用寿命,又满足了安全性、节能环保的要求,特别适用于油田、井下、煤矿等特殊环境中,应用前景十分广阔。(The invention discloses an arc-free breaking circuit based on a contactor and a working method thereof.A power supply output end is connected on a capacitor, two ends of the capacitor are respectively connected with a T1 pole and a trigger-level G pole of a bidirectional thyristor which are connected in parallel with a main contact of an alternating current contactor to form a loop, and a resistor R is connected in series in the loop to limit and delay the current of the trigger loop. The invention utilizes the characteristics of fast conduction time and slow conduction time of the silicon controlled rectifier to ensure that no electric arc is generated in the process of opening and closing the contactor, thereby prolonging the service life of the contactor, meeting the requirements of safety, energy conservation and environmental protection, being particularly suitable for special environments such as oil fields, underground, coal mines and the like, and having wide application prospect.)

1. The utility model provides a no arc divides disconnected circuit based on contactor, its characterized in that includes the bidirectional thyristor who connects in parallel with contactor main circuit switch KG, and bidirectional thyristor's T1 utmost point and T2 utmost point are connected with the both ends of switch KG respectively, and bidirectional thyristor's G utmost point is connected condenser C's negative pole, and condenser C's positive pole passes through resistance R and bidirectional thyristor's T1 utmost point and is connected, and condenser C connects in parallel has the power that can charge for it.

2. The contactor-based arcless trip circuit of claim 1 wherein the power source is an induction coil wound around a pull-in coil at the control terminal of the ac contactor.

3. The contactor-based arcless trip circuit of claim 2, wherein the induction coil charges capacitor C through a bridge rectifier.

4. The contactor-based arcless trip circuit of claim 1, wherein the triac is a three-quadrant triac.

5. The method of claim 1, wherein the power source charges the capacitor C when the switch K is closed;

when the switch KG is disconnected, the capacitor C is discharged firstly, the bidirectional thyristor is conducted through the current at two ends of the T1 pole and the G pole of the bidirectional thyristor, and the current of the main circuit of the contactor flows through the bidirectional thyristor; when the capacitor C finishes discharging and the alternating current passing through the T1 pole and the T2 pole of the bidirectional triode thyristor passes through zero, the triode thyristor is naturally turned off.

6. The method of claim 5, wherein the power source is an induction coil wound around a pull-in coil of a control terminal of the ac contactor, the induction coil generating an induction current to charge the capacitor C when the pull-in coil is energized.

7. The method of claim 6, wherein the induction current generated by the induction coil is rectified by a bridge rectifier to charge a capacitor C.

Technical Field

The invention belongs to the field of contactors, and particularly relates to an arc-free breaking circuit based on a contactor and a working method.

Background

The contactor is an electric appliance which utilizes a coil to flow current to generate a magnetic field in industrial electricity to close a contact so as to control a load, and in the aspect of electrical engineering, because an alternating current and direct current main loop can be quickly cut off and a device which can be frequently connected with a large-current control (certain types can reach 800 amperes) circuit can be frequently connected, the contactor is frequently applied to a motor as a control object and can also be used for controlling electric loads such as factory equipment, an electric heater, a working mother machine, various electric power units and the like, the contactor not only can be connected with and cut off the circuit, but also has a low-voltage release protection effect, is large in control capacity and is suitable for frequent operation and remote control. Is one of the important elements in an automatic control system.

When the coil of the contactor is electrified, the current of the coil can generate a magnetic field, the generated magnetic field enables the static iron core to generate electromagnetic attraction to attract the movable iron core and drive the alternating current contactor to act, the normally closed contact is opened, the normally open contact is closed, and the normally closed contact and the normally open contact are linked. When the coil is powered off, the electromagnetic attraction disappears, the armature is released under the action of the release spring, the contact is restored, the normally open contact is disconnected, the normally closed contact is closed, and the working principle of the direct current contactor is similar to that of a temperature switch.

Alternating current contactor utilizes the main contact to come the switching circuit, switches on control circuit with auxiliary contact, and the main contact generally is normally open contact, and auxiliary contact often has two pairs of normally open contact and normally closed contact, and miniature contactor also often uses as auxiliary relay cooperation main circuit, and alternating current contactor's contact is made by silver-tungsten alloy, has good electric conductivity and high temperature resistant ablation nature. The power of the action of the AC contactor comes from a magnetic field generated by AC passing through a coil with an iron core, an electromagnetic iron core is formed by overlapping two 'mountain' -shaped young silicon steel sheets, one of the electromagnetic iron cores is fixed with the iron core and sleeved with the coil, the working voltage can be selected in various ways, in order to stabilize the magnetic force, a short circuit ring is added on the attraction surface of the iron core, and the AC contactor is reset by a spring after power failure.

The existing composite alternating current contactor is a composite based on an alternating current contactor and a thyristor, the excitation mode of an electromagnetic coil is mostly an alternating current mode, namely electricity is directly taken from a 380V bus, magnetic flux alternation in a magnetic circuit can generate iron core loss in an iron core and generate noise, so that the efficiency of electrical equipment and the power factor of a power grid are reduced, the controllability is poor, the operating frequency is low, and a lot of electric energy needs to be consumed when the electromagnet is kept.

Because of the arc ablation, the electrical service life of the contactor is not only ten times different from the mechanical service life, but also greatly reduced according to different use environments, and the electrical service life can be reduced from ten-thousand times to several-thousand times, even to thousands of times. More seriously, under the action of arc light, the main contact is welded but cannot jump, so that production accidents are caused, and enterprises suffer great economic losses. Meanwhile, arc current also easily causes impact on a power grid, and interferes with noise pollution to reliable work of other electric appliances and instruments.

The existing contactor has the disadvantages of common arc extinguishing effect, potential safety hazard, complex structure and inconvenient installation.

Disclosure of Invention

The invention aims to overcome the defects and provide an arc-free breaking circuit based on a contactor and a working method, which can effectively avoid the generation of arc discharge.

In order to achieve the purpose, the arc-free breaking circuit based on the contactor comprises a bidirectional thyristor connected with a contactor main circuit switch KG in parallel, a T1 pole and a T2 pole of the bidirectional thyristor are respectively connected with two ends of the switch KG, a G pole of the bidirectional thyristor is connected with a negative pole of a capacitor C, a positive pole of the capacitor C is connected with a T1 pole of the bidirectional thyristor through a resistor R, and the capacitor C is connected with a power supply capable of charging the capacitor C in parallel.

The power supply is an induction coil wound on a pull-in coil at the control end of the alternating current contactor.

The induction coil charges the capacitor C through a bridge rectifier.

The bidirectional controllable silicon adopts a three-quadrant bidirectional controllable silicon.

A working method of an arc-free breaking circuit based on a contactor is characterized in that when a switch KG is closed, a power supply charges a capacitor C;

when the switch KG is disconnected, the capacitor C is discharged firstly, the bidirectional thyristor is conducted through the current at two ends of the T1 pole and the G pole of the bidirectional thyristor, and the current of the main circuit of the contactor flows through the bidirectional thyristor; when the capacitor C finishes discharging and the alternating current passing through the T1 pole and the T2 pole of the bidirectional triode thyristor passes through zero, the triode thyristor is naturally turned off.

The power supply is an induction coil wound on the attraction coil at the control end of the alternating current contactor, and when the attraction coil is powered on, the induction coil generates induction current to charge the capacitor C.

The induced current generated by the induction coil is rectified by the bridge rectifier to charge the capacitor C.

Compared with the prior art, the arc-free breaking circuit based on the contactor is reasonable and compact in structure and ingenious in design, the advantages of the contactor and the silicon controlled rectifier are combined into a whole, the characteristics of fast conduction time and slow conduction time of the silicon controlled rectifier are utilized, no arc is generated in the processes of opening and closing the contactor, the service life of the contactor is prolonged, the theoretical service life of the contactor reaches the mechanical life of the contactor, the requirements of safety, energy conservation and environmental protection are met, the arc-free breaking circuit is particularly suitable for special environments such as oil fields, underground and coal mines, and the application prospect is very wide.

Furthermore, the power supply is an induction coil wound on the pull-in coil at the control end of the alternating current contactor, power can be supplied through the pull-in coil at the control end of the contactor, an external power supply is not needed, the cost is saved, and the structure is simplified.

In the working method of the arc-free breaking circuit based on the contactor, the T1 pole and the G pole of the bidirectional thyristor are directly connected with two ends of a capacitor which supplies power for triggering conduction, and the G pole is connected with the negative pole of the capacitor, so that the working state of the bidirectional thyristor is only in two-quadrant and three-quadrant at the moment of disconnecting the contactor, and the condition that a larger trigger current I is needed when four-quadrant works is effectively avoided_GAnd duration of trigger current, lower dV_t/d_tThe bidirectional thyristor has the advantages that the load-bearing capacity is high, the gate-level degradation is easy to occur, the working process of the bidirectional thyristor is very short, the bidirectional thyristor is only conducted for a few milliseconds in the breaking process of the contactor, theoretically, the working process of the bidirectional thyristor is less than half wave of 50Hz alternating current, the reliability of the thyristor is fully guaranteed, and the impact influence of surge current is reduced.

Drawings

Fig. 1 is a circuit diagram of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Referring to fig. 1, an arcless breaking circuit based on a contactor comprises a bidirectional thyristor connected with a contactor main circuit switch KG in parallel, a T1 pole and a T2 pole of the bidirectional thyristor are respectively connected with two ends of the switch KG, a G pole of the bidirectional thyristor is connected with a negative pole of a capacitor C, a positive pole of the capacitor C is connected with a T1 pole of the bidirectional thyristor through a resistor R, and the capacitor C is connected with a power supply capable of charging the bidirectional thyristor in parallel.

Preferably, the power supply is an induction coil wound on a pull-in coil at the control end of the alternating current contactor, and the induction coil charges the capacitor C through a bridge rectifier.

Preferably, the bidirectional triode thyristor is a three-quadrant bidirectional triode thyristor.

A working method of arc-free breaking circuit based on contactor is as follows, contactor switch KG is closed, induction coil wound on suction coil of control end of AC contactor charges capacitor C in power-on process of control end of contactor through bridge rectifier, and capacitor C is connected to two ends of T1 pole and trigger G pole of bidirectional thyristor parallel connected with main contact of AC contactor separately, thus, once control end is cut off, before moving and static contacts of contactor are separated (moving contact hold-down spring rebounds to free state), capacitor C discharges in advance, bidirectional thyristor is conducted in advance through current at two ends of T1 pole and trigger G pole, main circuit current flows through bidirectional thyristor, and when capacitor C discharges completely (less than gate trigger current I)_GT) And when the alternating current flowing through the T1 pole and the T2 pole passes through zero, the silicon controlled rectifier is naturally turned off, so that electric arcs are not generated completely in the process of separating the moving contact and the static contact, and the current flows through a contact system of the contactor and the bidirectional silicon controlled rectifier does not work in the process of closing the contacts.

Because the charging and discharging time constant tau of the capacitor is RC, in order to ensure that the bidirectional thyristor is in a conducting state in the breaking process of the moving contact and the static contact of the contactor, parameters of the resistor R and the capacitor C are properly selected and matched.