Contactor and electrical equipment

Abstract

The invention relates to a contactor and electrical equipment, and the contactor comprises an electromagnetic module which comprises a first coil and a second coil, the first end of the first coil is connected with the first end of an AC power supply, and the second end of the first coil is connected with the first end of the second coil; the topological structure module comprises a relay, and all ends of a topological structure are connected with the second end of the first coil, the second end of the second coil, the tap of the first coil and the second end of the alternating current power supply respectively; in the initial stage of starting of the contactor, a gap between a movable iron core and a static iron core of the contactor is large, inductive reactance of a first coil and a second coil is small, starting current flowing through a relay in the topology structure module is large, and a normally open contact of the relay is closed; when the movable iron core and the static iron core of the contactor are contacted, the inductive reactance of the first coil and the second coil is increased, the holding current flowing through the relay in the topology structure module is reduced, and the normally open contact of the relay is disconnected. The method is safe and reliable.

Description

Technical Field

[0001] This application relates to the field of electrical technology, and in particular to a contactor and electrical equipment. Background Technology

[0002] With the rapid development of automation, artificial intelligence, smart sensors, computer technology, control technology, and electronic technology, control electrical appliances are playing an increasingly important role and have become more widely used. There are many types of control electrical appliances, such as AC contactors and DC contactors, which can be used to frequently connect or disconnect various terminal electrical appliances over long distances. They are commonly used in the control of everyday equipment such as electric motors, transformers, and lighting equipment. Their applications are broad, playing a vital role in agriculture, industry, transportation, and all aspects of daily life and production, significantly impacting people's lives and socio-economic development.

[0003] However, in traditional energy-saving operation schemes for AC contactors, a common practice is to employ a dual-coil structure and electronic control module. In the dual-coil scheme, a thicker-diameter starting coil generates sufficient electromagnetic force to complete the engagement, while a thinner-diameter holding coil engages after engagement to maintain the state. The two are switched via an electronic switch. Power supply to some coils is cut off using electronic switches such as thyristors. These methods can reduce coil losses and temperature rise during long-term holding states of the contactor to a certain extent.

[0004] However, in addition to increasing the complexity of the circuit, the control module of the electronic switch also needs to consider its environmental adaptability. Its active detection and timing logic may malfunction due to component aging or environmental interference, such as switching too early when the voltage fluctuates or the load changes, causing the contactor to not engage properly or to release abnormally. Summary of the Invention

[0005] Therefore, it is necessary to provide a contactor and electrical equipment that can ensure safety and reliability while also having a wide range of environmental adaptability to address the aforementioned technical problems.

[0006] In a first aspect, this application provides a contactor, the contactor comprising:

[0007] An electromagnetic module includes a first coil and a second coil, wherein a first end of the first coil is connected to a first end of an AC power supply, and a second end of the first coil is connected to the first end of the second coil.

[0008] The topology module includes a relay, and each end of the topology is connected to the second end of the first coil, the second end of the second coil, the tap of the first coil, and the second end of the AC power supply, respectively.

[0009] In the initial stage of contactor startup, the gap between the moving iron core and the stationary iron core of the contactor is large, the inductive reactance corresponding to the first coil and the second coil is small, and the current flowing through the first coil and the second coil is the starting current; when the moving iron core and the stationary iron core of the contactor come into contact, the inductive reactance corresponding to the second coil and the first coil increases, the current flowing through the second coil and the first coil is the holding current, and the starting current is greater than the holding current;

[0010] The relay is configured to close its normally open contact when it detects that the current flowing through the first coil and the second coil is a starting current, and to open its normally open contact when it detects that the current flowing through the first coil and the second coil is a holding current.

[0011] In one embodiment, the tap of the first coil is connected to the normally open contact of the relay via a first diode, the second end of the first coil is connected to the normally open contact of the relay, the second end of the second coil is connected to the first end of the third coil in the relay, the normally open contact of the relay is connected to the second end of the AC power supply via a second diode, and the third coil in the relay is connected to the second end of the AC power supply via a third diode.

[0012] In one embodiment, the first coil is a tapped coil; or the first coil comprises two independent coils connected in series, each independent coil having an equal or unequal number of turns, and the magnitudes of the starting current and the holding current are adjusted based on the wire diameter or number of turns of each independent coil.

[0013] In one embodiment, the topology further includes a capacitor and a resistor, with a first terminal of the capacitor connected to a first terminal of a third coil in the relay, a second terminal of the capacitor connected to a first terminal of the resistor, and a second terminal of the resistor connected to a second terminal of the third coil in the relay.

[0014] When the contactor is started, the capacitor stores energy; the energy stored in the capacitor provides energy for the delayed disconnection of the relay after the normally open contact of the relay is closed and during the initial stage of contact between the moving iron core and the stationary iron core of the contactor, so that the closing time of the normally open contact of the relay is greater than the time required for the contactor to start and fully engage.

[0015] Furthermore, the third coil in the relay is connected in series with the winding circuit formed by the first coil and the second coil, so the relay cannot be engaged if at least one of the first coil and the second coil fails.

[0016] In one embodiment, the size of the capacitor is used to change the start and stop timing of the relay; and / or

[0017] The resistor is a variable resistor, and its value is used to adjust the start and stop time of the relay.

[0018] In one embodiment, the third diode is used to block the leakage of electrical energy stored in the capacitor.

[0019] In one embodiment, the first diode is used for inductive energy recovery freewheeling of the first coil and the second coil in the electromagnetic module.

[0020] In one embodiment, the second diode is used to allow a half-wave starting current to flow through the first coil when the normally open contact of the relay is closed.

[0021] In one embodiment, the topology module further includes:

[0022] The fourth diode has its first terminal connected to the first terminal of the third coil in the relay;

[0023] The Zener diode has its first end connected to the second end of the fourth diode, and its second end connected to the second end of the AC power supply.

[0024] The fourth diode and the Zener diode are used to prevent the relay from overcurrent and to block the freewheeling circuit of the third coil of the relay, thereby increasing the pull-in current threshold of the relay and preventing the normally open contacts of the relay from closing again.

[0025] Secondly, this application also provides an electrical device including the contactor described above.

[0026] The aforementioned contactor and electrical equipment, including an electromagnetic module, comprises a first coil and a second coil. A first end of the first coil is connected to a first end of an AC power supply, and a second end of the first coil is connected to a first end of the second coil. A topology module, including a relay, comprises terminals connected to the second end of the first coil, the second end of the second coil, a tap of the first coil, and the second end of the AC power supply. In the initial startup phase of the contactor, the gap between the moving and stationary iron cores is large, resulting in low inductive reactance for the first and second coils, and the current flowing through them is the starting current. When the moving and stationary iron cores of the contactor come into contact, the inductive reactance for the second and first coils increases, and the current flowing through them is the holding current, with the starting current exceeding the holding current. The relay is used for detection... When the current flowing through the first and second coils is detected as the starting current, the normally open contact of the relay closes; when the current flowing through the first and second coils is detected as the holding current, the normally open contact of the relay opens. In this way, the natural change in coil reactance during the contactor's engagement process is directly used as the control signal: in the initial stage of startup, the reactance is small and the current is large. This starting current drives the relay in the topology module to operate, connecting the entire coil to the circuit to ensure reliable engagement; after engagement is completed, the reactance increases significantly, and the current flowing through the same relay automatically decreases to the release threshold, the relay opens, and the circuit automatically switches to an energy-saving holding state powered only by a portion of the coils. Thus, the holding current is less than the starting current, achieving the purpose of energy saving. Moreover, throughout the entire process, no external power supply or active control is required. The self-identification and self-switching of the state are achieved solely through pure hardware circuitry, making the entire contactor electromagnet assembly very safe, simple, and reliable. Attached Figure Description

[0027] Figure 1 A circuit diagram of a contactor according to one embodiment;

[0028] Figure 2 This is an assembly diagram of a contactor circuit diagram according to one embodiment.

[0029] Explanation of reference numerals in the attached figures:

[0030] J, Relay; L1, First coil; L2, Second coil; D1, First diode; D2, Second diode; D3, Third diode; D4, Fourth diode; C, Capacitor; DW, Zener diode; R, Variable resistor; Electromagnetic modules; Moving iron core; , static iron core. Detailed Implementation

[0031] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0034] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0036] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0037] Combination Figures 1 to 2 As shown, Figure 1 A circuit diagram of a contactor according to one embodiment; Figure 2 This is an assembly diagram of a contactor circuit diagram according to one embodiment.

[0038] The contactor provided in this application includes: an electromagnetic module ⑤ and a topology module.

[0039] Among them, the electromagnetic module ⑤ includes a first coil L1 and a second coil L2. The first end of the first coil L1 is connected to the first end of the AC power supply, and the second end of the first coil L1 is connected to the first end of the second coil L2.

[0040] The topology module includes a relay J, and each end of the topology is connected to the second end of the first coil L1, the second end of the second coil L2, the tap of the first coil L1, and the second end of the AC power supply, respectively.

[0041] In some alternative embodiments, the first coil L1 is a tapped coil; or the first coil L1 comprises two independent coils connected in series, each independent coil having an equal or unequal number of turns, and the magnitude of the starting current and holding current is adjusted based on the wire diameter or number of turns of each independent coil.

[0042] In this embodiment, a relay J is used to connect the first coil L1 and the second coil L2. If the second coil L2 fails, the first coil L1 will not be able to operate.

[0043] In the initial stage of contactor startup, the gap between the moving iron core ⑥ and the stationary iron core ⑦ of the contactor is large, the inductive reactance of the first coil L1 and the second coil L2 is small, and the starting current flowing through the relay J in the topology module is large, so that the normally open contact of the relay J closes; when the moving iron core ⑥ and the stationary iron core ⑦ of the contactor come into contact, the inductive reactance of the first coil L1 and the second coil L2 increases, the holding current flowing through the relay J in the topology module is small, and the normally open contact of the relay J opens.

[0044] During the initial startup phase, the gap between the moving iron core ⑥ and the stationary iron core ⑦ of the contactor is large, resulting in low inductive reactance of the first coil L1 and the second coil L2. Consequently, the current flowing through the first coil L1 and the second coil L2 is the large starting current. The path of this starting current is: the first terminal of the AC power supply, the first coil L1, the second coil L2, the third coil of relay J, the third diode D3, and the second terminal of the AC power supply. Due to the large starting current, relay J is energized, meaning its normally open contacts close. At this point, the first coil L1 is fully connected to the circuit, and the contactor begins to engage. Simultaneously, capacitor C charges to store energy.

[0045] During the contactor's engagement process, relay J maintains its position for a short delay. After relay J engages, capacitor C discharges through the parallel circuit, keeping relay J engaged for a brief period to ensure that the moving iron core ⑥ and stationary iron core ⑦ of the contactor are fully engaged. At this time, the first coil L1 remains fully connected, with a sufficiently large current to ensure proper engagement.

[0046] After the moving iron core ⑥ and stationary iron core ⑦ of the contactor are fully engaged (the gap between the moving iron core ⑥ and stationary iron core ⑦ is approximately zero), the coil inductive reactance increases significantly, and the holding current flowing through relay J decreases to a point where it cannot maintain engagement. Relay J releases, and its normally open contact opens. The current flowing through the second coil L2 and the first coil L1 is the holding current. At this time, the path of the holding current is: the first terminal of the AC power supply, the first coil L1, the second coil L2, the third coil of relay J, and the third diode D3, etc. The holding current is greatly reduced and is only used to maintain the engaged state, thus achieving energy saving.

[0047] The normally open contact of relay J is closed when the current flowing through the first coil L1 and the second coil L2 is detected as a starting current; and the normally open contact of relay J is opened when the current flowing through the first coil L1 and the second coil L2 is detected as a holding current.

[0048] In summary, during the initial startup phase, the inductive reactance is low and the current is high. This current drives relay J in the topology module to operate, connecting the entire coil to the circuit to ensure reliable engagement. After engagement, the inductive reactance increases significantly, and the current flowing through the same relay J automatically decreases to the release threshold. Relay J then disconnects, and the circuit automatically switches to an energy-saving holding state powered only by a portion of the coil. Throughout this process, no external power supply or active control is required; the self-identification and self-switching of the state are achieved solely through hardware circuitry. In the above embodiment, the automatic switching between startup / holding states based on changes in inductive reactance significantly reduces holding power consumption.

[0049] In some alternative embodiments, the tap of the first coil L1 is connected to the normally open contact of the relay J via the first diode D1, the second end of the first coil L1 is connected to the normally open contact of the relay J, the second end of the second coil L2 is connected to the first end of the third coil in the relay J, the normally open contact of the relay J is connected to the second end of the AC power supply via the second diode D2, and the third coil in the relay J is connected to the second end of the AC power supply via the third diode D3.

[0050] The first diode D1 is used for inductor energy recovery and freewheeling in the first coil L1 and the second coil L2 of the electromagnetic module.

[0051] When the current in the electromagnet coil (inductor) is cut off or reduced, the inductor will generate a reverse induced electromotive force (Lenz's law). The direction of this electromotive force is to try to maintain the original current direction, and its magnitude is proportional to the rate of change of current. If not handled, it may generate high voltage spikes and damage the components. Therefore, the first diode D1 is introduced as a freewheeling diode to provide a release path for the inductor current, converting the magnetic field energy into electrical energy for recovery or consumption, while enhancing the magnetic field force of the electromagnet when the pulsating DC crosses zero.

[0052] In some alternative embodiments, the topology further includes a capacitor C and a resistor R, with a first terminal of the capacitor C connected to a first terminal of the third coil in the relay J, a second terminal of the capacitor C connected to a first terminal of the resistor R, and a second terminal of the resistor R connected to a second terminal of the third coil in the relay J.

[0053] When the contactor starts, capacitor C stores energy. The energy stored in capacitor C provides energy for the delayed disconnection of relay J after the normally open contact of relay J closes and at the beginning of the contact between the moving iron core ⑥ and the stationary iron core ⑦ of the contactor, so that the closing time of the normally open contact of relay J is greater than the time required for the contactor to start and fully engage.

[0054] The relay's third coil L3 is connected in series with the entire winding circuit (first coil L1 and second coil L2). If any one of the coils (first coil L1 and second coil L2) fails, the relay will not be able to engage.

[0055] In this application, the primary function of capacitor C is to provide a time delay to ensure the completion of the engagement process. The contactor's core requires tens of milliseconds of mechanical movement time from startup to full engagement. Initially, although relay J engages immediately due to the large current, if it releases before the core closes due to the reduced current, engagement will fail. At this time, capacitor C, connected in parallel with the relay J coil, discharges its stored energy to provide a sustaining current to the relay J coil, keeping it engaged during the core's movement and providing a crucial time margin for mechanical action. This time delay is entirely adaptive, and its duration is naturally determined by the capacitance of capacitor C, the circuit resistance R, and the coil current.

[0056] Secondly, capacitor C acts as an energy buffer and recovery hub during switching. When relay J is released and the main circuit is disconnected, the magnetic field energy stored in the contactor coil (especially the second segment of the disconnected first coil L1) forms a freewheeling current through the first diode D1. This energy is not simply dissipated by resistor R, but is efficiently fed back to capacitor C to replenish its charge. This not only suppresses induced voltage spikes that may damage the contacts, but also increases the voltage level of capacitor C, enhances its delay capability, and realizes the recycling of energy within the system.

[0057] In the above embodiment, the discharge of capacitor C is used to briefly hold relay J, ensuring reliable engagement.

[0058] In some alternative embodiments, the size of capacitor C is used to change the start-up and turn-off timing of relay J; and / or resistor R is a variable resistor R, the size of which is used to adjust the start-up and turn-off timing of relay J.

[0059] The size of capacitor C directly determines the "delayed turn-off" time window. During the startup phase, capacitor C charges to store energy. When the contactor core begins to close and the coil inductive reactance increases, causing the current to decrease, relay J should release. However, at this time, capacitor C, connected in parallel across relay J, begins to discharge. Its stored charge continuously supplies power to the relay J coil, forcibly maintaining its engaged state. The larger the capacitance of capacitor C, the more charge it stores, the longer the discharge time constant, and the longer relay J is forcibly held. This ensures that even with contactors of different models and varying engagement times, or under conditions where low grid voltage slows the engagement speed, by selecting a capacitor C of appropriate capacity, relay J can be guaranteed to turn off only after the contactor is fully engaged, completely avoiding engagement jitter or failure caused by premature switching.

[0060] The variable resistor R provides continuous adjustment of the starting and stopping current thresholds. Resistor R is connected in series in the power supply circuit of relay J's coil, and its resistance directly affects the total inductive reactance and current of the circuit. Increasing the resistance reduces the coil inductive reactance required to reach relay J's pull-in voltage (i.e., requires a larger core gap), thus slightly delaying the relay J's starting action. Simultaneously, it increases the minimum current required to maintain relay J's pull-in, causing relay J to release prematurely when the current drops to a certain higher level. Conversely, decreasing the resistance makes relay J easier to start and releases later. By adjusting this variable resistor R, the operating sensitivity of relay J can be calibrated to precisely match parameter differences between different batches of coils, power supply voltage fluctuations, or adapt to different holding current requirements, thereby optimizing the operating boundaries of the entire system.

[0061] In this application, capacitor C controls the duration of the turn-off delay to ensure the action is completed; resistor R adjusts the critical point of the action threshold to optimize response characteristics. Together, they configure adjustable timing logic and a comparison reference for this purely hardware adaptive circuit, upgrading it from a circuit with fixed characteristics to an adaptable and calibrable general-purpose energy-saving control platform.

[0062] In some alternative embodiments, a third diode D3 is used to block the leakage of electrical energy stored in capacitor C.

[0063] The third diode D3 is connected in series in the discharge circuit of capacitor C or in the branch connecting to the relay J coil. Its core function is to establish a unidirectional discharge path for capacitor C, ensuring that the energy stored in capacitor C can only be released along a preset, useful path, specifically for maintaining the delayed engagement of relay J. If the third diode D3 is not present, the energy of capacitor C may be lost through leakage or short circuit during the negative half-cycle of the AC current or through other parallel branches (such as the second coil L2), resulting in a weakened or even failed delay effect.

[0064] In some alternative embodiments, the second diode D2 is used to allow a half-wave starting current to flow through the first coil L1 when the normally open contact of the relay J is closed.

[0065] After relay J actuates, its normally open contact closes. At this time, the second diode D2, in conjunction with a certain contact, forms the power supply path control for the first coil L1. Specifically, the second diode D2 may allow current to flow through the entire coil of the first coil L1 during one half-cycle of the AC current (e.g., the positive half-cycle), generating the large electromagnetic force required for startup. During the other half-cycle (negative half-cycle), due to the unidirectional conductivity of the second diode D2, current cannot flow through this path, and the current in the first coil L1 becomes zero or is supplied with a smaller sustaining current through other paths (such as through the first diode D1). Thus, the first coil L1 actually operates in half-wave rectified power supply mode during the startup phase.

[0066] On the one hand, the DC component of the half-wave current can generate a stable electromagnetic attraction, which is beneficial to the smooth start of the contactor; on the other hand, it cleverly utilizes the natural turn-off of the diode to automatically limit the current peak and coil temperature rise during the start-up phase without the need for additional control signals, thus achieving an optimized balance between starting force and electrical stress.

[0067] In some optional embodiments, the topology module further includes a fourth diode D4 and a Zener diode DW. The first terminal of the fourth diode D4 is connected to the first terminal of the third coil in the relay J; the first terminal of the Zener diode DW is connected to the second terminal of the fourth diode D4, and the second terminal is connected to the second terminal of the AC power supply. The fourth diode D4 and the Zener diode DW are used to prevent overcurrent in the relay J and to block the freewheeling circuit of the third coil of the relay, thereby increasing the pull-in current threshold of the relay J and preventing the normally open contacts of the relay J from closing again.

[0068] This branch provides a discharge path when the currents in the first coil L1 and the second coil L2 attempt to generate excessively high reverse electromotive force due to transient processes (such as a sudden change in inductive reactance caused by rapid closure of the iron core). Since the Zener diode DW is set above the operating voltage of relay J but below the coil insulation withstand voltage, it can clamp the voltage peak across the coil within a safe range, protecting the relay J coil and other components in the drive circuit (such as capacitor C and other diodes) from being broken down by high voltage.

[0069] At the instant relay J is de-energized (when the coil current needs to decay), the inductor generates a self-induced electromotive force (EMF) to maintain the current direction. Normally, this energy would be slowly dissipated through a freewheeling diode, thus prolonging the release time of relay J. However, in this case, the polarity of the fourth diode D4 is reversed, so the self-induced EMF cannot form a freewheeling path through this branch. Therefore, the magnetic field energy stored in the coil can only be rapidly dissipated across the coil's own resistance R, causing a sharp drop in current. As a result, relay J is forced to release quickly without any delay.

[0070] The fourth diode D4 and the Zener diode DW are used to prevent overcurrent in relay J and to block the freewheeling circuit of relay J winding, thereby changing the working characteristics of relay J release process, preventing relay J from re-engaging, and improving the reliability of the working sequence of the entire topology module.

[0071] Optionally, this application also provides an electrical device including the contactor in any of the above embodiments.

[0072] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A contactor characterized by, The contactor comprises: An electromagnetic module comprising a first coil and a second coil, a first end of the first coil being connected to a first end of an alternating current power supply, a second end of the first coil being connected to a first end of the second coil; A topology module comprising a relay, each end of the topology being connected to a second end of the first coil, a second end of the second coil, a tap of the first coil and a second end of the alternating current power supply respectively; In the initial stage of starting of the contactor, a gap between a moving iron core and a static iron core of the contactor is large, corresponding inductances of the first coil and the second coil are small, and a current flowing through the first coil and the second coil is a starting current; when the moving iron core and the static iron core of the contactor are in contact, the corresponding inductances of the second coil and the first coil are large, a current flowing through the second coil and the first coil is a holding current, and the starting current is larger than the holding current; The relay is used for closing a normally open contact of the relay when detecting that the current flowing through the first coil and the second coil is the starting current, and opening the normally open contact of the relay when detecting that the current flowing through the first coil and the second coil is the holding current.

2. The contactor of claim 1, wherein The tap of the first coil is connected to the normally open contact of the relay through a first diode, the second end of the first coil is connected to the normally open contact of the relay, the second end of the second coil is connected to a first end of a third coil in the relay, and the normally open contact of the relay is connected to the second end of the alternating current power supply through a second diode, the third coil in the relay being connected to the second end of the alternating current power supply through a third diode.

3. The contactor of claim 2, wherein, The first coil is a coil with a tap; or the first coil comprises two independent coils connected in series, the number of turns of each independent coil being equal or unequal, and the sizes of the starting current and the holding current being adjusted based on the wire diameter or the number of turns of each independent coil.

4. The contactor of claim 2, wherein, The topology further comprises a capacitor and a resistor, a first end of the capacitor being connected to the first end of the third coil in the relay, a second end of the capacitor being connected to a first end of the resistor, and a second end of the resistor being connected to a second end of the third coil in the relay; When the contactor is started, the capacitor stores energy; after the normally open contact of the relay is closed, and in the initial stage of the moving iron core and the static iron core of the contactor being in contact, the capacitor provides the energy for the relay to be delayed to be opened, so that the closing time of the normally open contact of the relay is longer than the time required for the contactor to be started and fully attracted; And the third coil in the relay is connected in series with a winding loop composed of the first coil and the second coil, in the case of failure of at least one of the first coil and the second coil, the relay cannot be attracted.

5. The contactor of claim 4, wherein, The size of the capacitor is used to change the action time of starting and turning off of the relay; and / or The resistor is a variable resistor, and the size of the resistor is used to adjust the action time of starting and turning off of the relay.

6. The contactor of claim 4, wherein, The third diode is used to block the leakage of the energy stored in the capacitor.

7. The contactor of claim 2, wherein The first diode is used for the electric energy recovery freewheeling of the first coil and the second coil in the electromagnetic module.

8. The contactor of claim 2, wherein, The second diode is used for the first coil to flow through half-wave starting current when the normally open contact of the relay is closed.

9. The contactor of claim 2, wherein, The topology module further comprises: A fourth diode, a first end of which is connected to a first end of a third coil in the relay; A voltage stabilizing tube, a first end of which is connected to a second end of the fourth diode, and a second end of which is connected to a second end of the alternating current power supply; The fourth diode and the voltage stabilizing tube are used for preventing overcurrent of the relay, and blocking the freewheeling loop of the third coil of the relay, so as to improve the pick-up current threshold of the relay, and avoid the normally open contact of the relay from being closed again.

10. An electrical device, characterized by The contactor comprises any one of claims 1 to 9.

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