71 results about "Open contact" patented technology

The utility model discloses a control system for soft start of a motor in the papermaking industry, which comprises a soft starter RQ, a terminal 7 and a terminal 10 of the soft starter RQ are in short circuit, a terminal 8 and a terminal 9 of the soft starter RQ are in short circuit, the terminal 8 and the terminal 9 of the soft starter RQ are both connected with one end of a normally open contact of a relay KA, and the other end of the normally open contact of the relay KA is connected with the terminal 7 and the terminal 10; and the terminals L11, L12 and L13 of the soft starter RQ are connected with one end of a contact of a contactor 2KM, and the other end of the contact of the contactor 2KM is connected with a motor M. The soft starter has the following advantages that the motor can continuously operate under the condition that the soft starter misreports a fault, and after the fault is misreported, the motor can still continuously operate and has circuit break protection, so that the condition that components are damaged cannot occur.

Provided is a two-degree-of-freedom ring frame repeated locking and circuit automatic switching gyro locking mechanism, which belongs to the technical field of inertial devices and comprises a shell, a shell cover arranged on the shell, an inner ring and an outer ring arranged in the shell, a limiting cam arranged on the inner ring, a locking pin elastically supported on the outer ring, and a locking cam arranged outside the outer ring; an electromagnet assembly is fixed on the shell cover, a torsional spring arm is installed in a U-shaped groove of the electromagnet assembly, an axle is positioned and installed through the torsional spring and a support arm hole to make the support arm generate a fixed shaft torque, an armature is installed in a hole of the electromagnet assembly, the armature is connected with the support arm through a pull rod, a pulley assembly and a limiting groove shaft are respectively riveted on a support arm bending space face positioning hole and are respectively used for precisely positioning the locking cam and the locking pin on the outer ring; the shell cover is symmetrically provided with two sides of an axis, and a normally open contact and a normally closed contact are respectively installed at an angle of 60° between the two sides. The gyro locking mechanism can realize the functions of gyro repeated locking reset, automatic switching and output of electric signals, and meets the requirements of automatic driving of a missile body.

The application discloses an OBD extension connecting line, which comprises a joint assembly, a switching circuit assembly, a circuit assembly and an extension assembly, the joint assembly comprises a male joint body, one side of the male joint body is fixedly connected with a trapezoidal socket, and a plurality of metal columns are embeddedly connected in the male joint body. The male joint body in the joint assembly is connected with the whole circuit of the device, a plurality of metal columns are arranged in the male joint body, the metal columns are connected with signals and main power supply, the main power supply is connected with the main power supply circuit through the contact metal wire, the main power supply circuit is connected with the first normally open contact and the second normally open contact, the first normally open contact and the second normally open contact are connected with the circuit connecting coil, the main power supply supplies power, the first normally open contact and the second normally open contact are adsorbed through the coil, the general power circuit is connected, when the main power supply is insufficient, the coil works, the first normally closed contact and the second normally closed contact are closed, and the auxiliary power supply is connected with the power circuit.

The application discloses an insulation protection structure and an electromagnetic relay, and relates to the technical field of electromagnetic relays. The application comprises an insulator, an installation cavity is formed in the insulator, a partition plate is arranged in the installation cavity, and an insulating sleeve is fixed to one side of the partition plate. The application separates the enameled coil from the normally open contact, the normally closed contact and the movable contact in another cavity by adopting the cooperation design of the insulating sleeve, the movable plate and the driving plate, and then when the enameled coil is powered off, the iron core stops adsorbing the magnetic adsorption plate, and the driving plate is reset under the action of the first torsional spring, the movable plate can be driven to slide to separate the movable contact from the normally open contact, and then the blocking assembly can be driven to move by the movable plate to block the electric arc between the normally open contact and the movable contact. Compared with the prior art, the application can solve the safety hazards of the discharge creeping of the electromagnetic relay and the safety hazards of the arc drawing of the electromagnetic relay.

The application discloses a socket power supply device and a connecting method which can prevent live plug-in and belongs to the technical field of design and manufacture of high-power load power supply socket. The socket power supply device comprises a power supply socket box, a plug and an electric machine. The connecting method which can prevent live plug-in comprises the following steps. The method for preventing the plug from being pulled out of the socket with electricity comprises the following steps: S11, unbuckling the buckle and providing external force to the plug to pull it out of the socket; S12, stroke impact rod is reset through a spring, the normally open contact of a micro switch is disconnected, and a power supply breaker is automatically tripped. The method for preventing the plug from being inserted into the socket with electricity comprises the following steps: S21, when the plug is not inserted into the socket, the normally open contact of the micro switch is disconnected, and the power supply breaker cannot be tripped; S22, providing external force to the plug to insert it into the socket and buckling the buckle; S23, stroke impact rod touches the micro switch, and the power supply breaker is normally tripped. The application can effectively prevent the problem of spark generated by live plug-in of the socket and increase the safety coefficient.

A positioning and rescue device for an unmanned underwater vehicle, comprising a battery (1), a switch (2), a protective resistor (3), an electromagnetic relay (4), a master control chip (5), a GPS positioning system (6), an igniter (7), a partition (8), an air bag (9), a shell (10), and a rope (11). The battery (1), the switch (2), the protective resistor (3), the electromagnetic relay (4) and the master control chip (5) are sequentially connected by means of wires to form a series circuit, and the igniter (7) and the GPS positioning system (6) are separately connected to the master control chip (5) by means of wires; two normally open contacts of a control loop of the electromagnetic relay (4) are respectively connected to two ends of a general power supply (15).

The utility model belongs to the technical field of relays, and discloses a contact system structure and a relay. The contact system structure comprises a base, an armature and movable contact spring assemblies, the armature is movably arranged on the base, an armature shaft is arranged on the armature, the movable contact spring assemblies are arranged on the armature shaft in a sleeving mode, each movable contact spring assembly comprises a movable contact spring, and switching of different connection modes is achieved through matching of movable contacts of the movable contact springs and corresponding normally-open contacts or normally-closed contacts on the base; when only one movable contact spring assembly is arranged, if no signal is output, the movable contact spring assembly is set to be in contact with the normally-closed contact to keep a normally-closed state (namely a normally-closed type), and if no signal is output, the movable contact spring assembly is set to be separated from the normally-open contact to keep a normally-open state (namely a normally-open type); when the two movable contact spring assemblies are arranged (in a conversion type), the armature drives the two movable contact spring assemblies to move so as to realize conversion between a normally open state and a normally closed state; the part structure of the relay is simplified and unified, and the operation difficulty of connection type switching is reduced.

The utility model discloses a motor protection circuit and ventilation equipment, which are characterized in that a first power supply input end is connected with a normally open contact of a first relay and a first end of a coil, a second power supply input end is connected with a normally closed contact of the first relay, and a third power supply input end is connected with a second end of the coil; therefore, when the first power supply input end, the second power supply input end and the third power supply input end receive abnormal power supply input signals, the first optocoupler, the second optocoupler, the first triode, the second triode, the third triode or the fourth triode can be controlled to be switched on and off through the relay. According to the invention, damage to the motor caused by wrong connection of the power supply can be avoided, the operation safety of the motor is improved, and the service life of the motor is prolonged.

The utility model belongs to the technical field of brake switches of electric forklifts, and particularly relates to a novel double-contact brake switch which is mainly composed of a pressing rod, a mounting shell, a contact brake assembly, an upper protective shell, a lower protective shell, a T-shaped screw, a locking nut and the like. According to the utility model, through the arrangement of the contact braking assembly, under the pressing action of the pressing rod, the normally-closed contact of the contact braking assembly is switched off, and the normally-open contact is switched on; under the pressing action of the pressing rod, a normally-closed contact of the contact braking assembly is closed and a normally-open contact of the contact braking assembly is opened under the reset action of the reset spring, so that contact braking of the braking switch is realized; besides, two groups of normally-closed contacts and two groups of normally-open contacts are respectively arranged, so that the contact of the contacts is ensured, and the condition of brake failure caused by the fact that the contacts cannot be contacted is avoided.

The present invention discloses a motor protection circuit and ventilation equipment. By connecting a first power input end with a normally open contact of a first relay and a first end of a coil, connecting a second power input end with a normally closed contact of the first relay, and connecting a third power input end with the second end of the coil, when the first power input end, the second power input end, and the third power input end receive an abnormal power input signal, the first optocoupler, the second optocoupler, the first transistor, the second transistor, the third transistor, or the fourth transistor can be controlled by utilizing a relay, and then the drive circuit of the motor can be controlled by the second relay and the third relay to achieve control of the operation of the motor. The present application can avoid damage to the motor caused by incorrect power connection, thereby improving the operating safety and service life of the motor.

The utility model relates to the technical field of pipeline manufacturing, and particularly discloses a pipeline forming vacuum detection alarm device which comprises an electric contact vacuum pressure gauge, a control circuit and an automatic packaging machine. The electric contact vacuum pressure gauge is electrically connected with the control circuit, and the control circuit is electrically connected with the automatic packaging machine. The control circuit comprises a first normally-open contact, a second normally-open contact, a third normally-open contact, a fourth normally-open contact, a fifth normally-open contact, a delay breaking normally-open contact, a normally-closed contact, a first normally-closed button, a second normally-closed button, a normally-open button, a first intermediate relay, a time relay, a vacuum abnormity alarm, an electromagnetic valve and a second intermediate relay. Specifically, one end of the first normally open contact is electrically connected with an electric contact vacuum pressure gauge. According to the utility model, unqualified products can be accurately detected.

The utility model relates to the field of electric connecting pieces, in particular to a quick butt joint plug, which comprises a first plug connector, a second plug connector, a third plug connector and a fourth plug connector, and is characterized in that one end is connected with a power line while the other end is provided with an open contact surface; one end part of the second plug connector is connected with a power line, and the other end part of the second plug connector is provided with an open contact surface; and the open contact surface of the first plug connector is in surface connection with the open contact surface of the second plug connector, so that the power line of the first plug connector and the power line of the second plug connector realize electric signal transmission. According to the utility model, the problems of high production cost, large connection difficulty and low connection efficiency caused by the fact that a production line of a male head and a production line of a female head need to be respectively arranged in the production process of the existing male and female butt joint plug and the needle-shaped bulge of the male head and the hole-shaped receiving end of the female head need to be completely aligned to realize connection are solved.

This invention provides a multi-detection access control system for energy storage containers, including a detection device. Each container door is equipped with a mechanical limit switch. When the door is closed, the normally open contact of the corresponding mechanical limit switch is open, and the normally closed contact is closed. When the door is open, the normally open contact of the corresponding mechanical limit switch is closed, and the normally closed contact is open. The normally open contacts of each mechanical limit switch are connected in series and form a circuit with the coil of a first relay and a first battery. The normally closed contacts of each mechanical limit switch are connected in parallel and form a circuit with the coil of a second relay and a second battery. The first and second relays are connected in parallel and are both connected in series between the first and second signal input terminals of the detection device. The detection device determines the door status based on whether there is continuity between the first and second signal input terminals. This invention ensures accurate and reliable reporting of access control signals and reduces the risk of missed detections.

The utility model relates to the technical field of temperature controllers, in particular to a temperature controller capable of monitoring forward and reverse plugging of a plug. According to the utility model, when the circuit is positively connected, the normally open contact of the first relay is closed, the first indicating lamp is electrified, and the positively connected signal input end of the control panel receives a high-level signal, so that related personnel can conveniently carry out subsequent program design; the current flowing through the circuit is extremely small and is equivalent to a high-resistance resistor, at the moment, the piezoresistor is equivalent to a disconnected switch, the first indicator lamp cannot be powered on, and the positive connection signal input end of the control panel cannot receive a high-level signal, so that related personnel can conveniently carry out subsequent program design, and then monitoring of positive and negative plugging of the plug is realized; positive and negative plugging of the plug can be monitored under the condition that the circuit is not short-circuited, and related prompts can be given.

The emergency stop switch convenient to install comprises a shell, a normally-closed contact, a normally-open contact and an emergency stop head, the normally-closed contact and the normally-open contact each comprise a moving contact mechanism with a moving contact and a pin with a static contact, a clamping area is formed on the side edge of each pin, the shell comprises an installation base, and the installation base is provided with a clamping groove. The mounting base is provided with an embedded groove for the lateral pin to insert, a clamping part is formed in the embedded groove, when the pin needs to be mounted on the mounting base, the pin can be laterally embedded from the embedded groove in the mounting base, and after the pin is embedded, the pin can be reliably mounted and limited on the shell through the matching of the clamping area and the clamping part; compared with the prior art, the installation convenience can be greatly improved, meanwhile, manual installation can be carried out, and the situation that the use reliability is affected due to the fact that installation is not in place similar to the prior art, or the situation that due to the fact that pins are longitudinally arranged similar to the prior art, package points possibly occur, the pins are inconsistent with design drawings, and the requirements of customers cannot be met possibly is avoided.

The invention relates to a CT automatic short circuit open circuit prevention contact structure, and belongs to the technical field of power system testing devices, the CT automatic short circuit open circuit prevention contact structure comprises a first reed, a second reed, at least one third reed and at least one fourth reed, the first reed comprises a first contact part, a second contact part, a third contact part and a connecting part, the second contact part and the third contact part are arranged on the connecting part, the second reed comprises a fourth contact part, the third reed comprises a fifth contact part and a sixth contact part, and the fourth reed comprises a seventh contact part; the first contact part, the second contact part and the fourth contact part are arranged in the same row of the socket; each third contact part corresponds to one third reed and one fourth reed, and the corresponding third contact part, third reed and fourth reed are located in the same row; the internal structure of the test socket is simplified, the assembly efficiency is improved, the number of conductive connection points is reduced, and the conductive reliability is improved.

The utility model relates to a clapper-type relay which specifically comprises a base assembly, a magnetic circuit assembly installed on the upper portion of the base assembly, a support assembly fixedly connected to the upper portion of the magnetic circuit assembly, a quick-action switch fixedly connected to the support assembly, a contact assembly rotatably connected to the lower portion of the magnetic circuit assembly, and a spring connected to the upper portion of the magnetic circuit assembly. The top of the contact assembly is connected with the quick-acting switch through a cam, the contact assembly comprises an armature assembly, after the magnetic circuit assembly is powered on, electromagnetic force is generated between the magnetic circuit assembly and the contact assembly, the contact assembly is attracted to move in the direction of the magnetic circuit assembly and attracted together, the cam moves, a normally-open contact of the quick-acting switch is powered on, and a normally-closed contact of the quick-acting switch is powered off. When the electromagnetic force disappears, the contact assembly is far away from the magnetic circuit assembly under the action of rebound force of the spring, the cam is in contact with the quick-acting switch, the normally-open contact of the quick-acting switch is disconnected, and the normally-closed contact of the quick-acting switch is connected, the structure is simple and compact, the size is small, the electromagnetic force is large, and the switching speed of the normally-open contact and the normally-closed contact of the quick-acting switch is high, and the reliability is high.

This utility model relates to the field of micro switch technology and discloses a novel tension spring micro switch, including a base. A slot is provided in the middle of the base, which engages with the right side of a movable bracket. A movable contact component is located above the movable bracket and is connected to the upper part of the movable bracket via a tension spring. A sliding groove is provided on the upper left side of the base, through which a button that cooperates with the movable bracket is slidably connected. Normally closed and normally open contact components, respectively, are located on the upper and lower sides of the right end of the movable contact component and engage with the base. A support foot is provided at the bottom of the base, with one side of the support foot located inside the base and connected to the left side of the movable contact component. This utility model applies to a novel tension spring micro switch, using a tension spring to connect the movable bracket and the movable contact component. The fulcrum of the movable bracket is located on the right side of the base, significantly increasing the switch lever arm length and ensuring contact pressure at the switch contacts while achieving the light pressure requirement of the overall switch.

The utility model relates to the field of microswitch, the utility model discloses a waterproof microswitch, include: casing, insulating button and pin subassembly, the lower end side of insulating button is equipped with trigger part, and the trigger part includes the trigger recess and non-trigger area that set gradually from top to bottom, and the pin subassembly includes common contact, normally closed contact and normally open contact, and the upper end of normally closed contact and normally open contact is equipped with normally closed contact point and normally open contact point respectively, and the upper end of common contact is equipped with elastic end, and the lower end of elastic end extends the setting along the direction of away from insulating button, and the one end of elastic end close to insulating button is abutted in trigger part, and the one end of elastic end away from insulating button is equipped with common contact point, and common contact point sets up between normally closed contact point and normally open contact point, when elastic end abuts at non-trigger area, common contact point abuts at normally closed contact point, when elastic end abuts in trigger recess inner wall, common contact point abuts at normally open contact point. Improved waterproof performance, prolongs the life.

The invention provides a laser protection circuit, and relates to the technical field of laser driving and safety protection. The protection circuit is arranged between a laser driver and a laser, and comprises a first interface connected with the laser driver; the first interface is provided with a first pin; the second interface is connected with the laser; the second interface is provided with a second pin; the relay array module comprises a double-pole double-throw relay with a common contact, a normally open contact and a normally closed contact; wherein the common contact is connected to the second pin; the normally open contact is connected to the first pin; the normally closed contact is connected to a grounding point; when the relay array module is in a power-off state, the common contact and the normally-closed contact are conducted, and the second pin is connected to the grounding point.

The application discloses an electromagnetic relay with reduced occupied space, comprising a base, a magnetic circuit part and a contact part, the contact part comprising at least one normally open contact group and at least one normally closed contact group, the normally open contact group and the normally closed contact group each comprising a dynamic spring part and a static spring part matched with each other, the dynamic spring part comprising a dynamic spring sheet and a dynamic contact; the normally open contact group and the normally closed contact group are arranged along a horizontal first direction on the base, and the free end of each dynamic spring sheet is respectively provided with a dynamic contact; the free end of the dynamic spring sheet of the normally open contact group and the free end of the dynamic spring sheet of the normally closed contact group are towards different sides of a second direction perpendicular to the first direction, and the dynamic spring sheet of the normally open contact group is inclined to extend to the direction of disconnecting the contact, and / or the dynamic spring sheet of the normally closed contact group is inclined to extend to the direction of closing the contact. The contact groups are more compact, and the occupied space of the product in the first direction is reduced.

The utility model relates to an anti-misoperation rolling mill journal sticking device control circuit, which comprises a first switch and a second switch, relays comprise a holding relay and a loosening relay, the first switch comprises a normally open contact 1 and a normally closed contact 1, the second switch comprises a normally open contact 2 and a normally closed contact 2, the normally open contact 1 and the normally open contact 2 are connected in series, and the normally open contact 1 and the normally closed contact 2 are connected in parallel. The other end of the normally-open contact 1 is connected with a power supply, the other end of the normally-open contact 2 is connected with a coil of a holding relay, the normally-closed contact 1 and the normally-closed contact 2 are connected in series, the other end of the normally-closed contact 1 is connected with the power supply, and the other end of the normally-closed contact 2 is connected with a coil of a loosening relay; a normally open contact of the clasping relay is connected with one coil of the electromagnetic reversing valve, and the loosening relay is connected with the other coil of the electromagnetic reversing valve. In the roller changing operation, the shaft holding device can act only when two workers operate the first switch and the second switch at the same time, and misoperation is avoided.

The utility model provides a switch test circuit and device. The switch test circuit comprises an input port, a leakage protector, a first fuse, a contactor contact switch, a transformer and a second fuse. The output end of the input port is sequentially connected with the leakage protector, the normally open contact switch, the transformer and the output port in series; a first fuse is connected in series between the leakage protector and the normally open contact switch; a second fuse is arranged between the transformer and the output port; and a control circuit is connected in parallel between the first fuse and the contactor contact switch. During use, a secondary test wire of a transformer of tested equipment is removed and connected with an output port, so that the equipment can be comprehensively detected by using safety voltage, including closing, opening, near and remote control, short circuit test, electric leakage test, comprehensive protector test, parameter modification, power-on test of part of components and maintenance of a control circuit. Through the switch test circuit, maintenance difficulty and time can be reduced, and personal and equipment safety can be guaranteed.

This application relates to the field of circuit changeover switch technology, specifically a dual-redundant arc-shaped contact limit switch, comprising: a base, an internal mounting cavity, and a through hole communicating with the mounting cavity at the top; a combination button, an upper stationary contact assembly, and a lower stationary contact assembly are disposed within the mounting cavity; the combination button includes two sets of conductive sheet assemblies arranged vertically, each conductive sheet assembly including a semi-circular arc-shaped elastic sheet; both the upper and lower stationary contact assemblies include two sets of sickle-shaped stationary contacts, which form arc-shaped surface contact with the arc-shaped elastic sheet; the combination button has a free state and a full-stroke state along the axial direction: in the free state, the upper arc-shaped elastic sheet contacts the upper stationary contact assembly, and the two normally closed contacts are connected; in the full-stroke state, the lower arc-shaped elastic sheet contacts the lower stationary contact assembly, and the two normally open contacts are connected, while the upper arc-shaped elastic sheet separates from the upper stationary contact assembly, and the normally closed contacts are open. This application improves the stability and reliability of contact resistance.

The invention discloses a circuit breaker time difference test system. The system comprises a circuit breaker to be tested and a tester, wherein the circuit breaker is provided with a phase selection closing device; a port binding post on one side of a fracture of the circuit breaker is short-circuited and connected to an N binding post of the tester, and port binding posts A, B and C on the other side are connected to corresponding binding posts A1, B1 and C1 in a first connecting phase of the tester; in addition, a port binding post on one side of a pair of normally-open auxiliary contacts of the circuit breaker is connected with a wire connected to an N binding post of the tester, and a port binding post on the other side of the normally-open auxiliary contacts is connected to a binding post A2 of a second phase of the tester; when the tester is used for testing the characteristics of the circuit breaker, besides the action time and synchronism of three-phase contacts of the circuit breaker are measured, corresponding auxiliary contacts of the circuit breaker are connected at the same time, operation is carried out according to testing regulations, the time difference of the main contacts and the auxiliary contacts during closing and opening of the circuit breaker can be accurately measured, and a basis can be provided for setting of related fixed values such as fast switching.

The present invention discloses an electromagnetic relay, comprising an electromagnetic system, a base assembly, and a transmission member. The normally closed contacts and normally open contacts of the movable spring assembly and the static spring assembly of the base assembly are correspondingly arranged. The elastic member is connected between the yoke and the transmission member. The armature is connected to the transmission member. The transmission member is mounted on the base. The transmission member can swing or move relative to the base. The transmission member includes a push rod and a retraction hook arranged corresponding to the movable spring assembly. When the electromagnetic system is energized in the forward direction, the armature is driven to move and thereby push the transmission member. The push rod pushes the movable spring assembly to close the normally open contact. When the electromagnetic system is energized in the reverse direction, the armature is driven to move in the reverse direction. The elastic member recovers its deformation and together pulls the transmission member back. The retraction hook pulls the movable spring assembly to close the normally closed contact. The electromagnetic relay of the present invention realizes bidirectional transmission through the mutual cooperation between the transmission member, the elastic member, and the yoke, and the cooperation between the push rod and the retraction hook of the transmission member and the movable spring assembly, thereby improving the reliability of the product.

The utility model discloses an armature reed assembly and a vacuum relay, and belongs to the field of vacuum relays. The armature reed assembly comprises an armature and a connecting support. The armature is provided with a mounting surface, a fixing part is arranged on the mounting surface, the connecting support is arranged on the mounting surface and comprises a support body and a connecting part, the connecting part is arranged at one end of the support body, the other end of the support body is arranged on the mounting surface, the support body is connected with the fixing part, and the fixing part supports the support body. In the embodiment of the invention, when the armature drives the bracket body to move and the bracket body drives the transmission rod to move through the connecting part, under the condition that the electromagnetic assembly applies the same force to the armature, the bracket body enables the transmission rod to be stressed more greatly, so that the normally open pressure of the normally open contact of the vacuum relay is increased.

The utility model relates to the technical field of relays, and discloses an automatic reversing device for a relay power supply, which comprises an installation shell, and a phase sequence relay and a time relay which are fixedly arranged in the installation shell, the reversing assembly comprises a fixed rod fixedly installed on the side wall of the time relay, when the device is used, a normally-closed contact is communicated with a control power source through a movable contact, a contact plate and a connecting plate under the normal condition, when the power source is switched, a movable rod drives the fixed rod to slide at the moment, and the time relay is switched. The movable contact in contact with the normally-closed contact slides away from the position in contact with the movable contact, the movable contact on the other side slides to be in contact with the normally-open contact, and at the moment, the contact plate on the side wall of the movable contact adjacent to the normally-open contact moves to be in contact with the side wall of the other side of the connecting plate at the lower end and is electrified; according to the device, the normally closed contact and the normally open contact can be switched by moving the movable rod, and the operation is simple.

The application relates to an anti-losing control safe driving circuit and a true safe anti-leakage protector, which is characterized in that: the safe driving circuit HAKM is used as a core device of the true safe anti-leakage protector, two trigger input ends V i1 , i2 of the core device are connected with two ends of a mutual inductor H secondary n3, a resistance R10 is connected between an e end and a driving end V DL of the secondary n3, an alternating current input end V S2 is connected with a series connection capacitor C9, a resistance R7, a fuse RD and a thermistor PTC, the series connection capacitor C9, the resistance R7, the fuse RD and the thermistor PTC are connected with a load line L2, the alternating current input end V S1 is connected with the load line N2, a relay J coil is connected between the driving end V DT and V DL , and two groups of normally open contacts of the relay J control the primary n1 and n2 of the mutual inductor H and the alternating current power supply of the load. If leakage or self failure occurs, the relay J can reliably disconnect the alternating current power supply. It can be seen that the application can prevent various fault losing controls and ensure that the power utilization is safe.

An Energy Reducing Maintenance Switch (ERMS) includes: a first switch that is normally open; a coil that is controlled by the first switch; a relay having instantaneous settings; a first normally-open contact that is controlled by the coil; a delay timer; and a second normally-open contact that is controlled by the delay timer. The coil is charged upon closing the first switch. The ERMS closes the first normally-open contact and energizes upon charging the coil. The delay timer starts to count from a first present time to a second preset time upon closing the first normally-open contact. The ERMS closes the second normally-open contact upon the delay timer starting to count. The ERMS activates the instantaneous settings of the relay, by activating an input signal to the relay, upon closing the second normally-open contact. While the delay timer counts from the first preset time to the second preset time, the second normally-open contact is closed.