There are many classification methods for low voltage circuit breakers. Depending on the type of use, there is a selective type (protective device parameters are adjustable) and a non-selective type (protective device parameters are not adjustable). Depending on the arc extinguishing medium, there are air type and vacuum type.
What is the use value of low voltage circuit breakers?
What parameters should be considered when selecting a low voltage circuit breaker?
What is a low voltage circuit breaker?
low voltage circuit breakers are electrical devices used for switching, controlling or protecting circuits with AC voltage of 1200 V and DC voltage of 1500 V. low voltage circuit breakers are an important part of the electrical industry and basic accessories in the machinery industry. In the power distribution system, low voltage switchgear mainly consists of various low voltage circuit breaker components. The functions and performances of low voltage circuit breakers play a crucial role. More than 80% of the electrical energy generated by power generation plants is distributed and used via low voltage circuit breakers. For each additional 10,000-kW power generation system, approximately 20,000 pieces of different low voltage circuit breakers are required to adjust them. Industrial automation systems also require various control panels, consoles, controllers and other products consisting of low voltage circuit breakers.
The type of circuit breaker includes the number of phases, the number of poles, the rated frequency, the arc extinguishing medium, the closing method and the shutdown method.
2) Rated power of the main circuit:
Main circuit ratings are:
rated operating voltage; rated current; rated short-term switching capacity; Design short-term current resistance.
The rated current of the universal circuit breaker is also divided into the rated current of the main circuit and the rated current of the frame plane.
3) Work system assessed:
The rated load system of low voltage circuit breakers can be divided into two types: 8-hour system and long-term system.
4) Subcircuit parameters:
The auxiliary circuit parameters of low voltage circuit breakers are mainly the characteristic parameters of auxiliary contacts. Universal circuit breakers usually have 3 pair closers and 3 pair openers for signal devices and control circuits; Compact circuit breakers usually have no auxiliary contacts.
low voltage circuit breakers are also called automatic air switches or automatic air circuit breakers or short circuit breakers. It is an electrical device that has both manual switching functions and automatic power failure, undervoltage, overload and short circuit protection. It can be used to distribute electrical energy, rarely start asynchronous motors, protect power supply lines and motors, etc. Its function corresponds to a fuse switch and overheating relay and other combinations. In addition, it is generally not necessary to replace parts after the residual current is interrupted, and it is widely used.
JIELI Electrical Engaged in research and development, production and supply chain management of MCB, RCCB and related supporting products.
The miniature circuit breakers are characterized by small size, simple structure and convenient operation. The contact material of the DC miniature circuit breaker is made of copper-based alloy and has been specially treated to reduce the contact resistance and reduce the temperature coefficient.
1.The upper limit of ambient air temperature must not exceed +40℃, the lower limit must not be lower than -5℃, and the average temperature value of 24 hours must not exceed +35℃;
Note 1: If the lower limit is -10 °C or -25 °C, the user must inform the manufacturer when ordering;
Note 2: If the upper limit exceeds +40℃ or the lower limit is below -25℃, the user should negotiate with the manufacturer.
2. The height of the site must not exceed 2000 m;
3. The relative humidity of the atmosphere does not exceed 50% if the ambient air temperature is +40 °C, and at lower temperatures a higher relative humidity is allowed, e.g. 90% at +20 °C. condensation should take appropriate measures;
4. degree of pollution: 2;
5. Installation category: Class II and Class III;
6.The external magnetic field of the installation site should not exceed 5x the earth's magnetic field in any direction;
7. Generally installed vertically, with a tolerance of 2° in each direction;
8.There should be no significant vibration or vibration at the installation site.
The miniature circuit breaker is characterized by advanced structure, reliable performance, strong switching power, beautiful appearance and compact appearance. It is mainly used in places with alternating current 50 Hz or 60 Hz, rated voltage below 400 V and rated operating current below 63 A. It is used for overload and short circuit protection of lighting, distribution lines and equipment in office buildings, residential buildings and similar buildings, and can also be used for the rare on-off operation and conversion of lines. Miniature circuit breakers are mainly used in various places such as industrial, commercial, high-rise and residential buildings.
1. Breakable contact connection. It consists of fixed contacts and movable contacts.
2. Equipment consisting of metal cylinders or insulating cylinders incorporating separable contact connections and arc extinguishing devices and transmissions.
3. The transmission device that drives the contact.
4. Arc extinguishing equipment.
When the miniature circuit breaker breaks the circuit, it uses a mechanical method to separate the moving contact and the fixed contact of the miniature circuit breaker. When closing, the movable contact and the fixed contact are closed by the opposite mechanical movement. During the closing and breaking of the load circuit, an arc is generated between the fixed contact and the movable contact. The arc generated during the opening process is much stronger than during the closing process. If the cut-off current is very large, especially when breaking a short circuit, the arc is very large, and it is often very difficult to disconnect the circuit.
JIELI Electrical maintains close relationships with customers in miniature circuit breaker industry, and is committed to strengthening p
roduction and operation, improving quality and safety.
low voltage circuit breakers are widely used in low voltage power distribution systems at all levels, to control the power of various mechanical devices, and to control and protect power connections.
Why are low voltage circuit breakers often used in series with low voltage fuses?
What is the function of the contacts of the low voltage circuit breaker?
How is the short-circuit protection of the low-voltage circuit breaker performed?
There are two reasons for this:
1.The role of low voltage circuit breakers is often used to interrupt the main power supply without the effect of current overload.
2.The role of low voltage fuses in the circuit means that the fuse will burst when the current in the circuit is overloaded.
The low voltage circuit breaker is commonly known as "air circuit breaker". Its main function is: It can connect short circuit with load and interrupt, and at the same time has overload and short circuit protection. In addition, additional accessories (e.g. leak protection accessories, undervoltage trigger accessories, working current trigger accessories, etc.) can be added to realize leakage protection, undervoltage protection, overvoltage protection, remote control and other functions.
What is the function of the contacts of the low voltage circuit breaker?
Contacts mechanically connected to the opening and closing mechanism of the circuit breaker's main circuit are mainly used to indicate the opening and closing status of the circuit breaker, and are connected to the circuit breaker's control circuit, to control the associated electrics devices by opening and closing the circuit breaker. or lock. For example, output signals to signal lamps, relays, etc. The universal circuit breaker has six pairs of contacts (three closers, three openers), the DW45 has eight pairs of contacts (four closers, four openers). The low voltage circuit breaker has a frame rated current of 100 A for a switching contact with an interruption point and 225 A, and more is a bridge contact structure. Normally closed, the conventional heating current is 6A. The number of switching games is equal to the total number of switching games of the circuit breaker.
Alarm contact for low voltage circuit breaker failure, and this contact only works when the circuit breaker triggers and interrupts, mainly used for free triggering, when the load of the circuit breaker is overloaded, short-circuited or under voltage, etc. Convert from original normally open position to closed position, turn on the indicator lights or bells, buzzer, etc. in the auxiliary circuit to indicate or remind the fault triggering state of the circuit breaker. Since the probability of the circuit breaker triggering freely due to a load failure is not too great, the life of the alarm contact is 1/10 the life of the circuit breaker. The working current of the alarm contact generally does not exceed 1A.
The short circuit protection of the thermal electromagnetic AC circuit breaker adopts the magnetic system used for the filtered rectifier circuit (DC), and the set current value of the original AC must be multiplied by the factor 1.3. The short circuit protection of the fully electromagnetic type is the same as that of the thermal electromagnetic type.
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The miniature circuit breaker is the most widely used terminal protection device in the construction of electrical terminals for power distribution. It is used for single-phase and three-phase short circuit, overload and overvoltage protection under 125 A, including single-pole 1P, two-pole 2P, three-pole 3P and four-pole 4P.
The typical size of the miniature circuit breaker is 18 mm width as module (1 bit, 1 P) and 9 mm as module. Friends should pay attention to their statement when buying to prevent the sizing of the distribution box top. Mistakes. In fact, 9 and 18 can be converted if we use it. Micro-Break has two frame currents 63A and 125A. The 1st position of the microfracture below 63 A is 18 mm, and the 1st position of the 125-frame current is 27 mm.
When a miniature circuit breaker in the distribution box needs to be replaced, it is accidentally jammed in the middle. We can only remove the wire and pull the clip on the bottom of the miniature circuit breaker to separate it from the guide rail. The clip is uncomfortable to pull by hand. Without a slotted screwdriver, it is not easy to lever.
Compact circuit breakers have a current carrying capacity of up to 2000 A. The maximum rated current of miniature circuit breakers is within 125 A.
Due to the capacity difference between the two, in the specific work, the effective area of the Compact circuit breaker is also larger than that of the miniature circuit breaker, and the wires connected to it are also relatively thick, which can reach more than 35 square meters, while the miniature circuit breaker is only suitable for connecting 10-wire below the square. Therefore, in general, for indoor conditions, it is better to choose compact circuit breakers for larger rooms.
When selecting a miniature circuit breaker, the following conditions should be considered:
1) The rated voltage of the miniature circuit breaker should not be less than the rated voltage of the line;
2) The rated current of the miniature circuit breaker and the rated current of the overcurrent trigger are not less than the calculated current of the line;
3) The rated short-circuit switching capacity of the miniature circuit breaker is not less than the maximum short-circuit current in the line;
4) The selection of miniature circuit breakers for power distribution shall take into account the short-term delayed short-circuit on-off capability and the coordination between the delay protection levels;
5) The rated voltage of the miniature circuit breaker's undervoltage trigger is equal to the rated voltage of the line.
JIELI Electrical has been active in the low voltage miniature circuit breaker industry for almost twenty years. Dedicated to research and development, production and supply chain management of MCB, RCCB and related supporting products. It is not only a production service provider solving supply chain problems, but also a manufacturer offering OEM and ODM production services.
There are many classification methods for low voltage circuit breakers. Depending on the type of use, a distinction is made between selective and non-selective species. Depending on the arc extinguishing medium, there are air type and vacuum type. low voltage circuit breakers have a wide range of capacities with a minimum of 4 A and a maximum of 5000 A.
What is the function of the low voltage circuit breaker?
What are the operating steps of a low voltage circuit breaker?
How does the overload protection of the low voltage circuit breaker work?
A low voltage circuit breaker, commonly known as automatic air switch, is a low voltage electrical device that can automatically interrupt a faulty circuit and has both control and protection functions. In low voltage circuits, it is used to interrupt and connect load circuits to control the operation and stopping of motors. If the circuit is overloaded, short-circuited, voltage loss and other faults, it can automatically turn off the faulty circuit to protect the safety of the circuit and electrical equipment. Its protective effect parameters can
be artificially adapted to the requirements of electrical equipment, and it is convenient and reliable to use. It is worth noting that after disconnecting the contact of the low voltage circuit breaker, the actuation handle is still in the "closed" position, and the handle must be moved to the "open" position, and then to the "closed" position. Position.
The operation of the low voltage universal circuit breaker is divided into electrical and manual operation.
Electric operation, first press energy storage button, after inserting the energy storage press close button. If there is no stored energy, press the close button directly. Manual operation, use the special control handle on the universal circuit breaker to manually store the energy up and down on the universal circuit breaker, and press the power button on the circuit breaker after the indicator is attached.
The low voltage circuit breaker uses time delay protection for long-term overload protection. When a thermally actuated (bimetal element) is used for long-term overload protection, its action source is i2r, and the effective value of AC is equal to the average value of DC, so no change is required. However, if the secondary current heating of the current transformer is adopted for high current specifications, the transformer cannot be used in the DC circuit and cannot be used.
If the long-delay overload trigger of low voltage circuit breaker is completely electromagnetic (hydraulic type, namely oil cup type), the time delay trigger characteristics should change, and the minimum operating current should be increased by 110% to 140% . Therefore, the fully electromagnetic AC trigger unit cannot be used in the DC circuit (if used, it must be redesigned).
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The miniature circuit breaker is installed on the interrupted distribution line to effectively protect the line and electrical equipment and avoid overload operation, resulting in certain safety risks to the line and electrical equipment. From this point of view, miniature circuit breakers have a high application value, and it makes sense to actively research and develop miniature circuit breakers. For more information about information about miniature circuit breaker, please read the following words.
Most miniature circuit breakers are frame structures, and some are assembled with discrete components. Working principle The AC operating power is rectified to obtain DC power to supply the exciter winding of the main contact coil of the miniature power switch for excitation operation; at the same time, the rotor of the miniature motor rotates through the transmission mechanism to drive the anchor, move up and down along the slip ring to close the contacts;
If the load is short-circuited or heavily overloaded, the miniature motor immediately stops rotating; When the load is restored, the miniature motor continues to work.
The miniature circuit breaker uses the thermal expansion of the bimetal sheet to bend the release lever so that the miniature circuit breaker triggers and plays the role of overload protection. There will be a certain time difference in overload protection. When a short circuit occurs, the current flows through the induction coil to create a strong magnetic field that pushes the lever to quickly trigger the miniature circuit breaker.
According to the various protection functions, the trigger can be divided into overcurrent trigger and power failure trigger.
If the line is generally overloaded, although the overload current cannot make the electromagnetic trigger work, the heating element can generate a certain amount of heat, causing the bimetal sheet to bend upwards during heating. Press the lever to release the hook and latch and release the main contact. The head is disconnected and the power supply is cut off.
The current maximum current of the miniature circuit breaker is 125A. Depending on the protection class, it is divided into B, C and D types, and according to the number of poles, it is divided into 1, 2, 3 and 4-poles, which are all models with leakage protection.
compact circuit breakers currently have a maximum current of 1600 A and a maximum rated voltage of 690 V. Depending on the ignition protection type, it is divided into distribution protection and motor protection; according to the number of poles, it is generally divided into 2, 3 and 4 poles; Models with leakage protection The current is below 630A.
JIELI Electrical has been focusing on the development and production of miniature circuit breakers for several years. And it is committed to providing perfect service to every customer from all over the world.
Jieli Electric officially moved its factory in June. The location was moved from Xiangyang Industrial Zone, Liushi Town, Yueqing City, to No. 81, Xiangbei East Road, Yishan Village, Liushi Town, Yueqing City.