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Transparent plastic case circuit breakers (hereinafter referred to as circuit breakers) are suitable for AC circuits with rated voltages of or and rated currents of up to, as power distribution, motor overload and short circuit For protection, it is also used for infrequent switching of circuits and infrequent starting of motors.
This product complies with standards.
2. Classification
The number of poles of circuit breakers is divided into single pole, two pole and three pole. Pole
The purpose of the circuit breaker is to distribute electricity and protect the motor (only applicable to three
poles).
3. Use environmental conditions
The altitude of the installation site does not exceed
/> Surrounding air temperature
The upper limit of the surrounding air temperature does not exceed +℃
The average value of the surrounding air temperature does not exceed +℃
The lower limit of the surrounding air temperature does not exceed ℃
Air conditions< br/> The relative humidity of the atmosphere does not exceed the maximum ambient temperature of +°C. It can have a higher relative humidity at lower temperatures. For example, at +°C, the maximum relative humidity is and takes into account the temperature changes that occur on the surface of the crystal. Condensation on the surface
Installation conditions
Install in a place without shock, vibration, rain or snow, and the inclination with the vertical plane does not exceed.
Installation Category III
Contamination Level .
The main contact is usually a normally open contact, while the auxiliary contact often has two pairs of normally open contacts and normally closed contacts. Small contactors are often used as intermediate relays in conjunction with the main circuit.
AC contactors The contacts are made of silver-tungsten alloy, which has good electrical conductivity and high temperature ablation resistance.
The power of AC contactor action comes from the magnetic field generated by AC passing through the coil with iron core. The electromagnetic core is composed of two " It is made of small silicon steel sheets stacked in the shape of a mountain. One of the fixed iron cores is covered with coils. The working voltage can be selected in a variety of ways. In order to stabilize the magnetic force, a short-circuit ring is added to the attraction surface of the iron core. After the AC contactor loses power, , relying on spring to return.
The other half is the movable iron core, which has the same structure as the fixed iron core, and is used to drive the main contact and auxiliary contact to close and open.
Contactors above ampere are equipped with arc extinguishing covers. , using the electromagnetic force generated when the circuit is disconnected, to quickly break the arc and protect the contacts.
The contact device can be operated at high frequency. When used as a power on and off control, the maximum operating frequency can reach times per hour. < br/> The service life of the contactor is very high, the mechanical life is usually millions to ten million times, and the electrical life is generally hundreds of thousands to millions of times.
Technology Development
The AC contactor is made as a whole, and its appearance and performance are constantly improving, but its function remains the same.
Contactor (picture)
No matter how far the technology has developed, ordinary AC contactors still have Its important position.
The air electromagnetic contactor (English) is mainly composed of a contact system, an electromagnetic operating system, a bracket, an auxiliary contact and a shell (or chassis).
Because of the AC electromagnetic contactor The coil is generally powered by AC power. After the contactor is energized, there is usually a high-decibel noise, which is also a characteristic of electromagnetic contactors.
After the 1990s, various countries studied the silence and power saving of AC contactor electromagnets. One of the basic feasible solutions was to use a transformer to step down the AC power supply and then convert it into a DC power supply through an internal rectifier. However, this is complicated. Controls are rare.
Vacuum contactor Vacuum contactor is a contactor whose contact system uses a vacuum degaussing chamber.
Semiconductor contactor Semiconductor contactor is a contactor that completes current operation by changing the on-state and off-circuit state of the circuit loop.
Permanent magnet contactor The permanent magnet AC contactor is a micro-power contactor formed by using the principle of same-sex magnetic poles repelling each other and opposite-sex magnetic poles attracting each other, and replacing the traditional electromagnet drive mechanism with a permanent magnet drive mechanism.
Main classification
According to the form of the main contact connection circuit, it is divided into DC contactor and AC contactor.
According to the operating mechanism, it is divided into electromagnetic contactor and permanent magnet contactor.
The permanent magnet AC contactor is formed by using the principle of magnetic poles of the same sex to repel each other and
Contactor (picture)
to attract the opposite sex to replace the traditional electromagnet drive mechanism with a permanent magnet drive mechanism. A micro-power contactor. Domestic mature product models,,,,,,,,,.
The permanent magnet with fixed polarity installed on the contactor linkage interacts with the variable polarity soft magnet solidified on the contactor base to achieve the purpose of attraction, retention and release. The variable polarity of the soft magnet is generated by the electronic module solidified with it to generate forward and reverse pulse currents of more than ten to twenty milliseconds, causing it to produce different polarities. According to the needs of the site, the control electronic module is divided into hydraulic contactor, pneumatic contactor and electromagnetic contactor according to the driving mode.
According to the action mode, it is divided into direct acting contactor and rotary contactor.
Main differences
The difference between contactors and relays The principle of a contactor is the same as that of a voltage relay, except that the load power controlled by the contactor is larger, so the volume is also larger. AC contactors are widely used in power interruption and control circuits. Relay is a small signal control electrical appliance, which is used for motor protection or automatic control of various production machinery.
The difference between a contactor and a circuit breaker. A contactor uses a coil to control the on and off of the circuit. When the contactor is energized
Siemens Relay
The normally open one closes, and the normally closed one opens. This is how to control it.
It is true that circuit breakers are mainly used for protection. Its protection is currently more commonly used as three-stage protection, which is overload protection, short-circuit short-delay, and short-circuit long-delay. There are also some under-voltage, over-voltage and other protection functions. It depends on the brand and model. Its opening and closing can be manual or electric. There are three installation methods: fixed type and drawer type. According to the size of the current and the level of the working voltage, it can be divided into low voltage
Contactors are mainly used for industrial control. Generally, the loads are mostly motors. Of course, there are some heaters and dual power switching. The contactor is switched on and off by controlling the coil voltage. According to the different structures of arc extinguishing, it can be divided into vacuum contactor and ordinary contactor. According to different control voltages, they can be divided into DC contactors and AC contactors. Its main accessory is the auxiliary contact. The contact resistance between contacts increases
Contactor (Picture)
The temperature of the contact surface is too high, causing the surface contact to become point contact, and even non-conduction. The causes of this failure include oil stains, lint, foreign matter on the contacts, long-term use, oxidation of the contact surface, defects caused by arc ablation, burrs or formation of metal shaving particles, etc., and jamming in the moving parts.
The treatment method is: for oil stains, lint or foreign matter on the contacts, you can wipe them with cotton cloth dipped in alcohol or gasoline. . If it is a silver or silver-based alloy contact
Contactor (picture)
When the contact surface forms an oxide layer or is slightly burned or blackened under the action of arc, it generally does not affect the work. You can use alcohol and Clean with gasoline or carbon tetrachloride solution. Even if the surface of the contact is burnt and uneven, you can only use a fine file to remove the surrounding splash beads or burrs. Do not file too much to avoid affecting the life of the contact.
For copper contacts, if the degree of burn is minor, you only need to use a fine file to repair the uneven areas. However, it is not allowed to polish with fine emery cloth to avoid quartz sand particles remaining between the contacts and unable to maintain the Good contact. If the burn is severe and the contact surface is low, the contact must be replaced with a new one.
If the moving part is stuck, it can be disassembled for inspection.
Maintenance and inspection Frequent or periodic inspection of the operation of the contactor
Contactor (picture)
Performing necessary maintenance is an important measure to ensure reliable operation and extend its life. When inspecting and repairing, disconnect the power supply first and follow the steps below.
, Appearance inspection to remove dust, use a cotton cloth dipped in a small amount of gasoline to wipe off the oil, then wipe dry with a cloth and tighten all the screws of the crimped wires to prevent them from loosening and falling off, causing the connection parts to heat up. []
, arc extinguishing cover maintenance) Remove the arc extinguishing cover, and use a brush to remove the falling objects or metal particles in the cover. If the arc extinguishing cover is found to be cracked, it should be replaced in time. ) For the grid arc extinguishing cover, attention should be paid to whether the grid is intact or whether it is burnt, deformed, severely loose, or has a changed position. If it is not easy to repair, it should be replaced.
, Contact system inspection) Check whether the dynamic and static contacts are aligned and whether the three phases are closed at the same time
Contactor (picture)
And adjust the contact spring to make the three phases consistent. ) Shake the phase-to-phase insulation resistance value. When using a megohmmeter, its phase-to-phase resistance should not be lower than megohms.
) When the contact wear exceeds the thickness, or is severely burned or welded off, new parts should be replaced. Slight burn damage or hairiness or blackening on the contact surface does not affect the use and can be left alone. If it affects the contact, you can use a small file to smooth it and polish it. ) After repairing or replacing contacts, attention should be paid to contact spacing and overtravel. Contact overtravel will affect the final pressure of the contact. ) Check whether the auxiliary contact action is flexible and whether the static contact is loose
, iron core maintenance
) Wipe the end face with cotton yarn dipped in gasoline
Contactor (picture)
Remove oil or dust, etc.) Check whether all buffer parts are complete and in the correct position) whether the rivets are broken, resulting in loose ends of the iron core) whether the short-circuit ring is detached or broken, pay special attention to hidden cracks. If it is broken or causes serious noise, the short-circuit ring or iron core should be replaced) and check whether the electromagnet is well engaged and whether there is any misalignment.
, Maintenance of electromagnetic coil) The attraction coil of the AC contactor should be able to work reliably when the power supply voltage is the rated voltage of the coil. ) Check whether the electromagnetic coil is overheated. Coil overheating is reflected in the aging and discoloration of the outer surface. Coil overheating is generally caused by short circuit between turns. At this time, its resistance can be measured and compared with similar coils. If it cannot be repaired, it should be replaced. ) Whether the leads and wipers are open
Working conditions
Ambient air temperature The upper limit of the ambient air temperature + ℃ The lower limit of the ambient air temperature ℃ The average value of the ambient air temperature does not exceed + ℃.
Altitude The altitude of the installation site does not exceed.
Atmospheric conditions Atmospheric relative humidity does not exceed the monthly average maximum relative humidity of the wettest month when the ambient air temperature is +°C. Higher relative humidity can be achieved at lower temperatures. At the same time, the monthly average minimum temperature of that month +°C, taking into account condensation that occurs on the surface of the product due to temperature changes.
Pollution level The pollution level is level 1.
Technical parameters
Rated voltage The rated voltage on the nameplate of the contactor refers to the rated voltage on the main contact. The commonly used voltage levels are DC contactors, ,,, and other grades. AC contactor,,, and other grades. If a load is a three-phase induction motor, an AC contactor should be selected. Rated working voltage The rated working voltage is the same as the rated current and rated current. The rated current on the nameplate of the contactor refers to the rated current of the main contact. The commonly used current level is DC contactor,,,,,,. AC contactor,,,,,,,,,,. The above current means that the contactor is installed on an open control panel, and the contact operation does not exceed When working in a long-term working system, and the power supply continuity rate does not exceed that of open installation, the current is allowed to be increased ~ for cabinet installation, it is allowed to be increased ~. Those between the above situations can be increased or decreased as appropriate.
, Rated working current The rated working current of the main contact is determined by the rated working voltage, rated power, rated working system, usage category and shell protection type to ensure the normal operation of the contactor. The rated operating current of the auxiliary contact The rated operating current of the auxiliary contact is the auxiliary contact specified taking into account the rated operating voltage, rated operating frequency, usage category and electrical life
Maintenance methods for each component of the contactor
? Regular or Regularly checking the operation of the contactor and performing necessary maintenance are important measures to ensure reliable operation and extend its life. When inspecting and repairing, disconnect the power supply first and follow the steps below.
, Appearance inspection to remove dust, use a cotton cloth dipped in a small amount of gasoline to wipe off the oil, then wipe dry with a cloth and tighten all the screws of the crimped wires to prevent them from loosening and falling off, causing the connection parts to heat up.
, Contact system inspection) Check whether the dynamic and static contacts are aligned, whether the three phases are closed at the same time, and adjust the contact spring to make the three phases consistent. ) Shake the phase-to-phase insulation resistance value. When using a megohmmeter, its phase-to-phase resistance should not be lower than megohms. ) If the contact wear exceeds the thickness, or is severely burned or welded off, new parts should be replaced. Slight burns or hairiness or blackening of the contact surface do not affect the use, and it is not necessary to repair the arc extinguishing cover.) Remove the arc extinguishing cover and use a brush to remove the falling objects or metal particles in the cover. If the arc extinguishing cover is found to be cracked, it should be replaced in time. ) For the grid arc extinguishing cover, attention should be paid to whether the grid is intact or whether it is burnt, deformed, severely loose, or has a changed position. If it is not easy to repair, it should be replaced.
, Maintenance of electromagnetic coil) The attraction coil of the AC contactor should be able to work reliably when the power supply voltage is the rated voltage of the coil. ) Check whether the electromagnetic coil is overheated. Coil overheating is reflected in the aging and discoloration of the outer surface. Coil overheating is generally caused by short circuit between turns. At this time, its resistance can be measured and compared with similar coils. If it cannot be repaired, it should be replaced. ) Are the leads and wiper parts open?
?
, inspection of the iron core) Wipe the end face with cotton gauze dipped in gasoline to remove oil or dust, etc.) Check whether all buffer parts are complete and in the correct position) Rivets Whether there is any breakage, resulting in loosening of the end face of the iron core) Whether the short-circuit ring has fallen off or broken, pay special attention to hidden cracks. If it is broken or causes serious noise, the short-circuit ring or iron core should be replaced) Check whether the electromagnet is well engaged and there is current ?
AC contactor
AC contactor
AC contact Circuit breakers are widely used as power switching and control circuits. It uses main contacts to open and close circuits and auxiliary contacts to execute control instructions. The main contact generally only has a normally open contact, while the auxiliary contact often has two pairs of contacts with normally open and normally closed functions. Small contactors are often used as intermediate relays in conjunction with the main circuit. The contacts of the AC contactor are made of silver-tungsten alloy and have good electrical conductivity
Basic introduction to the basic composition, working principle, classification of models using connection methods
Basic classification of electromagnetic AC contactor, permanent magnet AC contactor
Basic components
The AC contactor mainly consists of four parts that make up the electromagnetic system, including the attraction coil, the moving iron core and the static iron core contact system, including three sets of main contacts and one to two sets of normally open and normally open contacts. Close the auxiliary contact, which is connected with the moving iron core to interlock with each other and is an arc extinguishing device. Generally, AC contactors with larger capacities are equipped with arc extinguishing devices to quickly cut off the arc and avoid burning the main contact insulation shell. And attached
Working principle When the coil is energized, the static iron core generates electromagnetic attraction, which pulls the moving iron core together. Since the contact system is linked to the moving iron core, the moving iron core drives the three moving contacts to run simultaneously. , the contacts are closed, thus turning on the power. When the coil is powered off, the suction force disappears and the linkage part of the moving iron core is separated by the reaction force of the spring, causing the main contact to disconnect and cutting off the power supply.
Use of connection method
Generally, a three-phase contactor has a total of one point, three inputs, three outputs, and two control points. The output and input correspond to each other and can be easily seen. If you want to add self-locking, you also need to connect a line from a terminal of the output point to the control point.
2. First of all, you should know the principle of AC contactor. It uses an external power source to apply to the coil to generate an electromagnetic field. When power is applied, the contact point is disconnected. After knowing the principle, you should figure out the contacts of the external power supply, which are the two contacts of the coil, usually at the bottom of the contactor, and on each side. The other inputs and outputs are generally on the upper part and can be identified at a glance. Also pay attention to the additional
model classification
in electrical engineering. Contactor is an automatic switcher used to connect or disconnect AC and DC main circuits or large-capacity control circuits with loads. The main control object is electric motors. It is also used for other electric loads, such as electric heaters and welding machines. For lighting equipment, contactors can not only connect and cut off circuits, but also have low-voltage release protection. The contactor control capacity is large. Suitable for frequent operation
AC contactor. It is mainly composed of electromagnetic mechanism, contact system, arc extinguishing device, etc. Commonly used are,,, and other series.
DC contactors are generally used to control DC electrical equipment. DC current is passed through the coil. The action principle and structure of the DC contactor are basically the same as those of the AC contactor.
But now the contactor models have been reclassified. They are all series. . .
Class contactors are used to control non-inductive or micro-inductive circuits. Class contactors are used to control the starting and breaking of wound asynchronous motors, and contactors can be used to frequently control the starting and breaking of asynchronous motors
/> Basic classification AC contactors can be divided into three types: electromagnetic type, permanent magnet type and vacuum type.
Commonly used AC contactors, , , and imported , , and other series.
Electromagnetic AC contactor
Structure
The contactor is mainly composed of electromagnetic system, contact system, arc extinguishing system and other parts.
①Electromagnetic system The electromagnetic system includes the electromagnetic coil and the iron core, which is an important part of the contactor, relying on it to drive the closing and opening of the contacts. ②Contact system contacts are the execution part of the contactor, including main contacts and auxiliary contacts. The function of the main contact is to connect and break the main circuit and control larger currents, while the auxiliary contact is in the control circuit to meet the requirements of various control methods. ③Off
Working principle When the contactor electromagnetic coil is not energized, the reaction force of the spring and the self-weight of the armature core keep the main contact in the open position. When the electromagnetic coil is connected to the control voltage (usually the rated voltage) through the control loop, the electromagnetic force overcomes the reaction force of the spring and attracts the armature to the static core, driving the main contact to close, turning on the circuit, and the auxiliary contact moves accordingly.
Permanent magnet AC contactor
Structure
The contactor is mainly composed of drive system, contact system, arc extinguishing system and other parts.
① Drive system The drive system includes electronic modules, soft iron, and permanent magnets. It is an important part of the permanent magnet contactor and relies on it to drive the closing and opening of the contacts. ②Contact system contacts are the execution part of the contactor, including main contacts and auxiliary contacts. The function of the main contact is to connect and break the main circuit and control larger currents, while the auxiliary contact is in the control circuit to meet various control methods
Working principle Permanent magnet AC contactor uses magnetic poles Based on the principle of same-sex repulsion and opposite-sex attraction, a micro-power contactor is formed by replacing the traditional electromagnet drive mechanism with a permanent magnet drive mechanism. The permanent magnet with fixed polarity installed on the contactor linkage interacts with the variable polarity soft magnet solidified on the contactor base to achieve the purpose of attraction, retention and release. Features of Soft Magnets The innovative technical feature of permanent magnet AC contactors is to replace the traditional electromagnet drive mechanism with a permanent magnet drive mechanism, that is, a control device composed of permanent magnets and microelectronic modules is used to replace traditional products. The electromagnetic device in the device has no working current during operation, only weak signal current. The microelectronic module contains six basic partial source rectification power supply voltages in real time
① The closing and holding of the traditional contactor is achieved by energizing the closing coil to generate electromagnetic force to overcome the opening spring. Once the current changes The electromagnetic force generated by the angel is not enough to overcome the reaction force of the spring, and the contactor cannot maintain the closing state. Therefore, the closing of the traditional AC contactor must be maintained by continuous energization of the coil. This current ranges from tens to tens of seconds. to thousands of mA. And forever
② Noiseless traditional AC contactor closing and maintenance relies on the coil to energize the silicon steel sheet to generate electromagnetic force, causing the dynamic and static silicon steel sheets to attract. When the grid voltage is insufficient or the surface of the dynamic and static silicon steel sheets is uneven or contains dust or foreign matter When waiting, noise will occur. The closing and holding of the permanent magnet AC contactor relies on the force of the permanent magnet, so there will be no noise.
③ No temperature rise Traditional contactors rely on the coil to generate sufficient electromagnetic force to maintain the attraction. The coil is composed of resistance and inductance. If current is passed through for a long time, it will inevitably generate heat. On the other hand, the magnet in the iron core The passage will also generate heat. These two types of heat work together in the contactor cavity, often causing the contactor coil to burn out. At the same time, the heat reduces the main contact capacity. The permanent magnet AC contactor relies on permanent
④ The contact does not vibrate. The holding of the traditional AC contactor is achieved by energizing the coil. The holding force is related to the current and magnetic gap. When the voltage changes between closing and opening, When the critical state of the gate fluctuates, the contactor is in a closed or open state, and will vibrate continuously, causing the contacts to be welded or burned, and the motor to burn out. The holding of the permanent magnet AC contactor relies entirely on the force of the permanent magnet. The holding is completed in one step, and the voltage
⑤ Long life and high reliability The life and reliability of the contactor are mainly determined by the life of the coil and contacts. . In traditional AC contactors, the coil and iron core will generate heat when it works. Especially when the voltage, current, and magnetic gap increase, it is easy to cause heat and burn the coil. However, there is no possibility of burning the coil in permanent magnet AC contactors. Contact ablation is mainly caused by arcs generated during opening and closing. And transmission
⑥ The permanent magnet magnetic circuit used by the anti-electromagnetic interference permanent magnet AC contactor is completely sealed, and will not be subject to external electromagnetic interference during use, nor will it cause electromagnetic interference to the outside world
⑦ The anti-shock control electronic module can control the set release voltage value, and can delay a certain period of time before sending out the reverse pulse current to achieve low voltage delayed release or power failure delayed release, so that the motor it controls is protected from grid voltage fluctuations. (shock power) and jump to stop, thereby maintaining the stability of the production system. Especially for enterprises with device-type continuous production, it can reduce the amount of electricity, steam, and natural gas used for venting and resuming production
Select maintenance
Select ① Select the corresponding category of contact according to the control object, number of operations, and usage category of the contactor device. ②Select according to the rated voltage of the line at the location of use. ③ Select the rated current of the main contact of the contactor according to the load capacity. ④ For the voltage level and current type of the attraction coil, the requirements of the control power supply should be considered. ⑤The capacity of the auxiliary contact should be selected according to the required number of interlocking circuits and the number of connections it is connected to
⑥For the connection and disconnection capabilities of the contactor, when selecting, attention should be paid to the loads in some usage categories, such as capacitors, Illuminators such as tungsten lamps have a large current value when turned on and a long on-off time, so there should be a margin when selecting. ⑦ Regarding the electrical life and mechanical life of the contactor, calculate the required electrical life based on the known average number of operations per hour and the service life of the machine. If the required electrical life cannot be met
Maintenance ① Inspection items during operation) The load passed Whether the current is within the rated value of the contactor) whether the contactor's opening and closing signal indication is consistent with the circuit status) whether the operating sound is normal, whether there is a discharge sound due to poor contact) whether the electromagnetic coil is overheated, whether the electromagnet's short-circuit ring Are there any abnormalities? ) Whether the arc extinguishing cover is loose or damaged) Whether the auxiliary contacts are burned)
② Maintenance When maintaining electrical equipment, the contactors should be maintained together.
)External maintenance, sweep external dust to check whether the fasteners are loose, especially the conductor connection part, to prevent loose contact and heat generation
)Contact system maintenance, check whether the positions of moving and static contacts are aligned, and whether the three Whether the phases are closed at the same time. If there is any problem, the contact spring should be adjusted to check the degree of contact wear. The wear depth should not exceed the contact point. If the contact is burned and falls off when welding is opened, it must be replaced in time. If the contact is slightly burned, it generally does not affect the use. Sandpaper is not allowed to be used when cleaning contacts. A shaping file should be used to measure the phase-to-phase insulated electrical conductors. The iron core part should be maintained and dusted, especially between the moving parts and the core suction contact surface. Check the tightening of the iron core. Loose cores will cause increased operating noise. If the core short-circuit ring falls off or breaks, it must be repaired in time.
) Electromagnetic coil maintenance quantity Check whether the coil insulation, resistance coil insulation is discolored or aged. The surface temperature of the coil should not exceed the temperature. Check the coil lead connection. If there is open welding or burning damage, it should be repaired in time.
) Maintenance of the arc extinguishing cover. Check whether the arc extinguishing cover is damaged. Check whether the position of the arc extinguishing cover is loose or changed. Remove metal particles and debris in the gaps of the arc extinguishing cover.
Working principle of vacuum AC contactor
The vacuum contactor uses vacuum as the arc extinguishing medium, and its main contact is sealed in a special vacuum arc extinguishing tube. When the operating coil
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