Circuit breakers, also known as automatic switches, air switches, etc., are common circuit protectors in homes and projects. When the working current exceeds the rated current, short circuit, loss of voltage, etc., the circuit is automatically cut off to achieve protection, except for the protection function It can also be used in conjunction with module units such as leakage, measurement, and electrical operation. In low-voltage power distribution systems, it is often used as a terminal switch or branch switch, replacing the usual fuse and knife switch in the past.
(1) Current limiting and undervoltage protection: When the wire is short-circuited, a large current will occur, which will cause the electrical appliance to burn out. The circuit breaker has this function. When the current is greater than the current of the circuit breaker, the switch will be closed and closed. , To achieve the purpose of power failure.
(2) Short-circuit protection: After using the circuit breaker, when the circuit is short-circuited and grounded, it will automatically clutch.
(3) Overload and overheating protection: Overload means that the load is too large, and the heating of the wire causes the reaction of the electromagnetic coil of the circuit breaker to solidly make it clutch.
(4) Isolation and phase-to-phase protection: Generally, the current below 30mA is normal and acceptable to the human body. If the leakage current is higher than this, it will be unsafe. Therefore, the circuit breaker can isolate the leakage current above 30mA by switching on and off within a few minutes. (This value is determined according to the parameters of the circuit breaker).
(5) Leakage protection: Everyone believes that leakage can only be caused to the earth. Others say that only the main switch and the induction switch can react. In fact, this is not complete. The circuit breaker, single P empty Turning on will also respond to leakage.
The internal structure of the circuit breaker uses the thermal expansion and bending of the bimetal to trigger the lever to trip the circuit breaker for overload protection. There will be a certain time difference in overload protection. When a short circuit occurs, current flows through the induction coil to generate a strong magnetic field, pushing the lever to quickly trip the circuit breaker.
Figure 1. Schematic diagram of circuit breaker
According to the different protection functions, the releases can be divided into overcurrent releases and voltage-loss releases, etc. There are three types of tripping methods: thermal, electromagnetic and double tripping.
When a general overload occurs in the circuit, although the overload current cannot cause the electromagnetic release to act, it can cause the thermal element to generate a certain amount of heat, which will cause the bimetallic sheet to be heated upwards, push the lever to disengage the hook and the lock, and bring the main contact The head is disconnected and the power supply is cut off.
When the line is short-circuited or severely overloaded, the short-circuit current exceeds the instantaneous tripping setting current value, and the electromagnetic tripping device generates enough suction force to attract the armature and hit the lever, so that the hook rotates upwards around the shaft seat and the lock is released , The lock breaks the three main contacts under the action of the reaction spring to cut off the power supply.
The trip mechanism of the switch is a set of linkage devices. When the main contact is closed by the operating mechanism, it is locked in the closed position by the lock hook. If there is a failure in the circuit, the relevant trip unit will act to release the hook in the trip mechanism, and the main contact will be quickly disconnected under the action of the release spring.
Circuit breaker model specification:
C65N 1P-: C1A C2A C4A C6A C10A C16A C20A C25A C32A C40A C50A C63A
C65N 2P-: C1A C2A C4A C6A C10A C16A C20A C25A C32A C40A C50A C63A
C65N 3P-: C1A C2A C4A C6A C10A C16A C20A C25A C32A C40A C50A C63A
C65N 4P-: C1A C2A C4A C6A C10A C16A C20A C25A C32A C40A C50A C63A
C65N 1P-: D1A D2A D4A D6A D10A D16A D20A D25A D32A D40A D50A D63A
C65N 2P-: D1A D2A D4A D6A D10A D16A D20A D25A D32A D40A D50A D63A
C65N 3P-: D1A D2A D4A D6A D10A D16A D20A D25A D32A D40A D50A D63A
At present, DZ series circuit breakers are used in homes, and the common ones are the following specifications: C16, C25, C32, C40, C60, C80, C100, C120, etc.
The common models in industry are: DW and DZ models for power circuits, which are divided into 20, 32, 50, 63, 80, 100, 125, 160, 250, 400, 600, 800, 1000A and other specifications.
Brand recommendation of circuit breaker 1. Schneider
Schneider Electric (China) Co., Ltd., Schneider Electric, top ten brands of switch sockets, electrical equipment-top ten brands of electrical equipment, has a glorious history of more than 170 years, a leading brand in the field of global power distribution equipment, a global energy efficiency management expert, a famous electrical field Manufacturer, specializing in power and automation management industry.
Brand recommendation of circuit breaker 2. ABB
ABB (China) Co., Ltd., the top ten brands of electrical equipment and the top ten electrical brands, is formed by the merger of two century-old international companies. It is a large multinational company with a century-old history, a Fortune 500 company in the world, and a major in the field of power and automation technology. Leading manufacturer, the world's first self-cooling transformer, high-voltage direct current transmission technology and the first industrial robot manufacturer.
Circuit breaker brand recommendation 3. CHINT
Zhejiang Chint Electric Co., Ltd., Top Ten Electrician Brands, Top Ten Electrical Equipment Brands in China, Well-Known Trademarks in China, Top 500 Chinese Private Enterprises, China's Largest Low-Voltage Electrical Appliance Manufacturers, Top 100 Enterprises in Zhejiang Province, Competitiveness of Chinese Private Enterprises Top 50, leading enterprises in China's electrical product manufacturing and listed companies.
Brand recommendation of circuit breaker 4. Delixi
China Delixi Holding Group Co., Ltd., top ten electrical equipment brands, top ten circuit breaker brands, well-known trademarks in China, top 500 Chinese enterprises, top 500 private enterprises in China, leading enterprises in China's electrical industry, deputy of China Industrial Economic Enterprise Federation Chairman, a large national industrial enterprise.
Circuit breaker brand recommendation 5. Merlin Gerin MGE
Schneider Electric's American Power Conversion Group (APC), Merlin Gerin MGE, top ten brands of circuit breakers, top ten UPS uninterruptible power supply brands, founded in 1920, the world's leading brand in the field of power distribution equipment, China's largest UPS research and development One of the manufacturers, a brand under the world famous electric company.
Circuit Breaker Brand Recommendation VI. Great Wall CNC
Great Wall Electric Group Co., Ltd. was established in 1988. The top ten brands of switch circuit breakers, the top ten brands of relays, the top ten electrical equipment brands, the well-known trademarks in China, the well-known trademarks in Zhejiang Province, the well-known export brands in Zhejiang, and the national A regional enterprise group, a national high-tech enterprise, an important backbone enterprise group in the electrical equipment industry, and a first-tier network supplier of Sinopec.
Circuit breakers are commonly used safe electrical equipment in the home. The quality of the circuit breaker is related to the safety of electricity at home. Therefore, it is necessary to buy a good quality circuit breaker. The following points will help to buy a high quality circuit breaker.
1. The most preliminary method is to look at the weight of the circuit breaker. Generally speaking, high-quality circuit breakers are made of flame-retardant PC plastic with a pure copper wire inside. The more turns, the heavier the quality.
2. Next, let’s look at the arc extinguishing cover inside the circuit breaker. The arc extinguishing cover is used to generate an arc when the circuit is short-circuited and overloaded. If the arc cannot be extinguished smoothly, a fire will occur. This is very important. It consists of nine iron plates.
3. Does the switch surface have IEC standards, CCC certification, Great Wall certification, PICC quality certification, and whether there are signs such as GB10963.
4. Try to choose a circuit breaker produced by a regular manufacturer, observe the workmanship, and shake it for a little noise, and pay attention to whether there are fake signs and appearance fonts.
5. Pay attention to the distinction of material color, the color of the handle, and whether the handle has good elasticity.
6. The coil is electromagnetically induced. If it is short-circuited or overloaded, the induction coil will pull the release to make it clutch. Therefore, the more copper coils in the circuit breaker, the better.
The circuit breaker selection is divided into two parts, one part is to learn how to look at the model specification of the circuit breaker, and the other part is to determine the circuit breaker specification that should be used at home.
The letter "D" in the circuit breaker model represents power, and the letter "C" represents lighting. At present, DZ series circuit breakers (miniature circuit breakers with leakage protection) are used in homes, and the common specifications are as follows: C16, C25, C32, C40, C60, C80, C100, C120, etc., where C represents the trip current, namely Take-off current, that is, when the current in the line is greater than this value, the circuit breaker will automatically trip, thus playing the role of protecting the circuit. For example, C32 means that the trip current is 32 amps. Generally, C32 is used to install 6500W water heaters, and C40 circuit breakers are used to install 7500W and 8500W water heaters.
Generally, the principle of circuit breaker selection: 1. The rated voltage of the circuit breaker must be greater than or equal to the rated voltage of the line; 2. The rated current of the circuit breaker and the rated current of the overcurrent release are greater than or equal to the calculated load current of the line.
The next step is to determine the type of circuit breaker suitable for your household needs. First, check the size of the wire. If the wire allows a larger circuit breaker, you can change to a larger circuit breaker, such as 1.5 square wire with C10 switch, 2.5 square wire Equipped with a C16 or 20 switch, a 4-square wire with a C25 switch, and a 6-square wire with a C32 switch. If the wire is too small, a dedicated wire should be used for high-power electrical appliances.
The total value of household load current should be:
1, first calculate the value of each branch current
①Pure resistive loads, such as light bulbs, electric heaters, electric fans, electric irons, electric blankets, rice cookers, electric frying pans, vacuum cleaners, air conditioners and other electrical appliances, as long as the indicated power is directly divided by the voltage, the formula I= Power/220v.
②Inductive loads, such as fluorescent lights, televisions, washing machines, etc., are slightly more complicated to calculate, so power consumption must be considered, and power factor must also be considered in specific calculations. For general inductive loads, the power calculated according to the specified load can be doubled. For example, the branch current of a 20W fluorescent lamp I=20W/220v=0.09A, doubled to 0.09A*2=0.18A (ratio Accurately calculated value is 0.15A, 0.03A more).
2, the total value of the load current is the sum of the current of each branch
Know the branch current and total current, you can choose the branch circuit breaker and the main switch circuit breaker, the main fuse, the main electric meter and the specifications of the branch wires, or check whether the specifications of the designed electrical components meet the safety requirements.
In order to ensure safety and reliability, the rated working current of electrical components should generally be greater than 2 times the required maximum load current. In addition, when designing and selecting electrical components, it is necessary to consider the possibility of an increase in electrical load in the future, leaving room for future demand.
There are generally four reasons for circuit breaker tripping: overload protection, circuit short-circuit protection, leakage protection, and undervoltage protection. These four reasons will cause the circuit breaker to trip.
There are the following situations when the circuit breaker trips:
1. The current setting value of the circuit breaker is too low, and the power of the load is greater than the rated power of the circuit breaker. For example, the switch settings of the cabinet air-conditioning circuit and the electric water heater circuit should be 20A instead of the 16A of the general circuit (the same is true for high-power bath heaters).
2. The load connector is not too firm, and some electrical appliances are manually wired, and the connector is not tight.
3. There is a short circuit in the circuit, check whether the electrical plug is dry.
4. The line is aging and leaking, causing both the live and neutral lines to have electricity. You can check the leakage protector. If it jumps, it means the electrical leakage.
5. If you make sure that there are no problems with the wiring and electrical appliances in your home, then the quality of the circuit breaker itself is not good enough.