Type
Voltage type leakage circuit breaker is used for low-voltage power grid where the neutral point of the transformer is not grounded. Its characteristic is that when a person gets an electric shock, a relatively high voltage appears on the neutral line to the ground, causing the relay to act and the power switch to trip.
Current-type leakage circuit breakers are mainly used in low-voltage power distribution systems where the neutral point of the transformer is grounded. Its characteristic is that when a person gets an electric shock, a leakage current is detected by the zero-sequence current transformer, the relay is activated, and the power switch is turned off.
Scope of application:
1. The CDL7 series leakage circuit breaker is suitable for AC 50Hz, rated voltage up to 400V, rated current up to 63A, and the action performance has nothing to do with the line voltage for household and similar purposes. It is mainly used for electric shock protection and indirect contact protection to people. When personal electric shock or grid leakage current exceeds the specified value, it indirectly protects the safety of people and electrical equipment. It can also be used as infrequent line protection under normal conditions. For operation conversion. When CDL7 series leakage circuit breakers are used in conjunction with CDB7, they can provide overload and short circuit protection.
2, DZL18 series leakage circuit breakers (hereinafter referred to as leakage circuit breakers) are suitable for AC 50Hz, rated working voltage 220V, In line circuits with a rated current of 32A and below, it is used to protect people from indirect contact, and to protect buildings and similar lines from overcurrent. It can also provide protection against fires caused by continuous ground faults due to overcurrent protection devices not operating. Leakage circuit breakers with over-voltage protection can also protect against over-voltage caused by grid faults. The product complies with GB 16916, GB 16917 and IEC 61008, IEC 61009 standards.
3, DZ20L series leakage circuit breakers (hereinafter referred to as leakage circuit breakers) are mainly suitable for AC 50Hz, rated working voltage of 380V, rated current to 630A in the distribution network, used to make indirect contact with people Protection can also be used to prevent fire hazards caused by equipment insulation damage and ground fault current generation, and can be used to distribute electrical energy and protect lines and power equipment from overload and short circuit. It can also be used as infrequent conversion of lines and infrequent starting of motors. For use. The product complies with GB 14048.2 and IEC 60947-2 standards.
4, DZL25 series leakage circuit breakers (hereinafter referred to as leakage circuit breakers) are mainly suitable for AC 50Hz, rated working voltage of 380V, rated current to 200A in the distribution network, used to make indirect contact with people Protection can also be used to prevent fire hazards caused by equipment insulation damage and ground fault current generation, and can be used to distribute electrical energy and protect lines and power equipment from overload and short circuit. It can also be used as infrequent conversion of lines and infrequent starting of motors. For use. The product complies with GB 6829, GB 14048.2 and IEC 60755, IEC 60947 standards.
5, DZ15LE series leakage circuit breaker, suitable for AC 50Hz, rated working voltage to 380V, rated current to 100A line, used to protect people from indirect contact, and can also be used to prevent equipment insulation Damage to the ground fault current caused by the fire hazard, and can be used to protect the circuit, the overload and short circuit of the motor, and can also be used for infrequent conversion of the circuit and infrequent starting of the motor. Products comply with GB 6829, GB 14048.2 and IEC 60755, IEC 60947 standards
6, DZ47LE This leakage circuit breaker is suitable for AC 50Hz, rated voltage 230V or 400V, rated current to 63A and below. Indirect contact protection for people, and overcurrent protection for buildings and similar circuits. It can also provide protection against fires caused by continuous ground faults due to overcurrent protection devices not operating. Leakage circuit breakers with overvoltage protection can also protect against excessive voltage rises caused by grid faults.
Selection principle
Select according to the purpose of use and the place where the electrical equipment is located
1) Protection against direct contact with electric shock
p>Because the direct contact with electric shock is more harmful and the consequences are serious, it is necessary to choose a more sensitive leakage circuit breaker. For electric tools, mobile electrical equipment and temporary circuits, the operating current should be installed in the circuit. 30mA, leakage circuit breaker with action time within 0.1s. For residential houses with more household appliances, it is best to install the electric energy meter after entering the household.
If an electric shock is likely to cause secondary damage (such as high-altitude operations), a leakage circuit breaker with an operating current of 15mA and an operating time within US should be installed in the circuit. For electrical medical equipment in hospitals, a leakage circuit breaker with an operating current of 6mA and an operating time within US should be installed.
2) Indirect contact and electric shock protection
Indirect contact and electric shock in different places can cause different degrees of personal injury. Therefore, different places should install different leakage circuit breakers. For places that are prone to electric shock and more harmful, it is required to use a leakage circuit breaker with a relatively high sensitivity. The risk of electric shock in a humid place is much greater than in a dry place. Generally, a leakage circuit breaker with an operating current of 15-30mA and an operating time of within 0.1s should be installed. For electrical equipment in the water, actions should be installed. The current is 6-10mA, and the operation time is within US. For electrical equipment where the operator must stand on a metal object or in a metal container, as long as the voltage is higher than 24V, a leakage circuit breaker with an operating current of less than 15mA and an operating time within US should be installed. For fixed electrical equipment with a voltage of 220V or 380V, when the shell grounding resistance is below 500fZ, a single unit can install a leakage circuit breaker with an operating current of 30mA and an operating time within 0.19. For large-scale electrical equipment with a rated current above 100A or power supply circuits with multiple electrical equipment, a leakage circuit breaker with an operating current of 50-100mA can be installed. When the grounding resistance of the electrical equipment is below 1000, it can be installed Leakage circuit breaker with operating current of 200-500mA.
Choose according to the normal leakage current of the circuit and equipment
1) Leakage circuit breaker for stand-alone. The operating current should be greater than 4 times the leakage current during normal operation of the equipment.
2) Leakage circuit breakers used in branch circuits, the operating current should be greater than 2.5 times the leakage current during normal operation of the line, and at the same time greater than 4 times the leakage current of the electrical equipment with the largest leakage current in the line .
3) The leakage current of the main line or the leakage circuit breaker of the overall protection of the whole network should be greater than 2.5 times of the leakage current during the normal operation of the grid.
If it is not easy to measure the leakage current of the circuit or electrical equipment, you can estimate it according to the followingempirical formula:< /p>
Lighting circuit or residential electricity circuit: the operating current of the leakage circuit breaker IDZ> ISJ/2000;
Power and lighting hybrid circuit: the operating current of the leakage circuit breaker IDZ> ISJ/ 1000.
In the formula, IDZ is the operating current of the leakage circuit breaker, and ISJ is the maximum current in the circuit.
1) Electrical equipment powered by single-phase 220V power supply should use two-pole two-wire or single-pole two-wire leakage circuit breakers.
2) Electrical equipment powered by a three-phase three-wire 380V power supply should use three-pole four-wire or four-pole four-wire leakage circuit breakers.
Precautions
Installation
1. Before installation, check whether the data on the nameplate of the leakage circuit breaker is consistent with the usage requirements.
2. Do not install too close to the high-current bus and AC contactor.
3. When the operating current of the leakage circuit breaker is greater than 15mA, the enclosure of the equipment protected by it must be reliably grounded.
4. The power supply mode, voltage and grounding form of the system should be fully considered.
5. When installing a leakage circuit breaker with short-circuit protection, sufficient arcing distance must be ensured.
6. The external connection control circuit of the combined leakage circuit breaker should use copper wire with a cross-sectional area of not less than 1.5m².
7. After the leakage circuit breaker is installed, the original grounding protection measures of the original low-voltage circuit or equipment cannot be removed. At the same time, the neutral line of the load side of the circuit breaker shall not be shared with other circuits to avoid malfunction.
8. The neutral wire and the protective grounding wire must be strictly distinguished during installation. The neutral wire of the three-pole four-wire and four-pole leakage circuit breaker should be connected to the circuit breaker. The neutral wire passing through the circuit breaker can no longer be used as a protective grounding wire, nor can it be repeatedly grounded or connected to the enclosure of electrical equipment. The protective ground wire must not be connected to the leakage circuit breaker.
9. The protection range of the leakage circuit breaker should be an independent circuit and cannot be electrically connected to other circuits. Leakage circuit breakers cannot be used in parallel to protect the same circuit or electrical equipment.
10. After installation, you should operate the test button to check whether the leakage circuit breaker can operate reliably. Under normal circumstances, it should be tested more than three times, and it can work normally.
Wiring
1. Wiring should be done in accordance with the power supply and load signs on the leakage circuit breaker, and the two should not be reversed.
2. The protection line must not pass through the zero-sequence current transformer. When a three-phase five-wire system or a single-phase three-wire system is adopted, the protection line must be connected to the protection trunk line at the inlet end of the leakage circuit breaker, halfway Do not pass through the zero sequence current transformer.
3. For single-phase lighting circuits, three-phase four-wire distribution lines and other lines or equipment that use a working neutral line, the neutral line must pass through a zero-sequence current transformer.
4. In the system where the neutral point of the transformer is directly grounded, once the leakage circuit breaker is installed, the working neutral line can only be used as the working neutral line after passing through the zero sequence current transformer. It cannot be repeatedly grounded, nor can it be connected to the working neutral line of other lines.
5. Electrical equipment can only be connected to the load side of the leakage circuit breaker. One end is not allowed to be connected to the load side and the other end to the power supply side.
6. Three-phase four-wire system or three-phase five-wire system where single-phase and three-phase loads are mixed, try to balance the three-phase load.
Common faults
Put on trip
1) The three-phase power line, including the neutral line, does not pass through the zero-sequence current transformer in the same direction. Correct the wiring. Yes.
2) The circuits where the leakage circuit breaker is installed and the circuit without the leakage circuit breaker are electrically connected, just separate the two circuits.
3) There are loads of one fire and one place in the line, and it is enough to eliminate such loads.
4) The working neutral line passing through the zero sequence current transformer has repeated grounding, and the repeated grounding should be eliminated.
5) The leakage circuit breaker itself is faulty and should be replaced.
Malfunction
1) Caused by overvoltage. For example, the circuit breaker can be activated when an operating overvoltage occurs in the line. In this case, a delay or impulse voltage non-acting leakage circuit breaker can be selected, or a resistance-capacitance absorption circuit can be installed between the contacts to suppress the overvoltage. Overvoltage absorbing device is put in the line.
2) Electromagnetic interference. If there are magnetic equipment or high-power electrical equipment nearby, the installation position of the leakage circuit breaker should be adjusted to keep away from such electrical components.
3) Circulation influence. If two transformers are operated in parallel, they have their own grounding. Because the impedances of the two transformers cannot be completely equal, this will generate circulating current in the grounding wire and cause the circuit breaker to operate. Just remove one grounding wire. In addition, the same transformer supplies power to the same load through two parallel circuits, and the currents in the two circuits may not be exactly the same, and circulating currents may occur. Therefore, the two circuits should be operated separately.
4) The insulation resistance of the working neutral line is reduced. When the insulation resistance of the working neutral wire is reduced, if the three-phase load is unbalanced, a relatively large working current will appear on the neutral wire and flow to other branches through the ground, so that leakage current can appear on each leakage circuit breaker , Causing the circuit breaker to malfunction.
5) Improper grounding. If the neutral line is repeatedly grounded, it will cause the leakage circuit breaker to malfunction.
6) The influence of overload or short circuit. If the leakage circuit breaker has short-circuit protection and over-current protection at the same time, a malfunction will occur when the setting current of the over-current protection release is not appropriate. At this time, adjust the setting current value.
National Standards
GB 10963-1989|Circuit breakers for household and similar places
GB 14048.2-1994|Low voltage switchgear and control equipment low voltage circuit breaker< /p>
GB 16916.1-2003|Residual current operated circuit breakers without overcurrent protection for household and similar purposes (RCCB) Part 1: General rules
GB 16916.21-2008|Household and Residual current operated circuit breakers (RCCBs) without overcurrent protection for similar purposes-Part 2.1: Applicability of general rules to RCCBs whose operating function is independent of line voltage
GB 16916.22-2008|Household and similar Residual current operated circuit breakers (RCCBs) without overcurrent protection for purposes of use. Part 2.2: Applicability of general rules to RCCBs whose operating functions are related to line voltage
GB 16917.1-2003|Household and similar uses Residual Current Operated Circuit Breaker (RCBO) with Overcurrent Protection Part 1: General Rules
GB 16917.21-2008|Residual Current Operated Circuit Breaker with Overcurrent Protection for Household and Similar Purposes (RCBO) Part 2.1: Applicability of general rules to RCBOs whose operating function is independent of line voltage
GB 16917.22-2008|Residual current operated circuit breakers with overcurrent protection for household and similar purposes (RCBO) Chapter 2.2 Part: Applicability of general rules to RCBOs whose action function is related to line voltage
GB 1984-1989|AC high-voltage circuit breaker
GB 4876-1985|AC high-voltage circuit breaker Charging current switching test
GB 7675-1987|Opening and closing capacitor bank test of AC high voltage circuit breaker
Development status
Statistics show that China in 2011 The market size of the low-voltage circuit breaker industry is 40 billion yuan. In the next few years, with the continuous growth of my country's new power generation and the rapid development of other downstream industries, the domestic market's demand for low-voltage circuit breaker products will continue to grow. Therefore, the market scale of my country's low-voltage circuit breaker industry will also grow rapidly. It is expected that By 2016, the market size of my country's low-voltage circuit breaker industry will be close to 80 billion yuan. From the end of the twentieth century to the beginning of the 21st century, major foreign companies have successively introduced new ACB and MCCB, and continued to improve and expand them. They have made major breakthroughs and innovations in terms of main technical performance, product structure, and new technology applications. Among them, Siemens of Germany is the most prominent. Its low-voltage electrical appliances that can communicate can form a very large industrial system, power distribution monitoring system and building automation system. The MDU series circuit breaker developed by Mitsubishi Corporation can directly realize the power energy monitoring network. System, equipment monitoring network system, etc. Low-voltage electrical appliances are widely used in various industries in the national economy, and are closely related to the fixed investment situation of the whole society. The beginning of the 21st century is a period of rapid development of China's low-voltage electrical appliance industry. The growth rate of my country's low-voltage electrical appliance industry has remained at 10%-15% in recent years. The market capacity of the low-voltage electrical appliance industry is closely linked to the development of the power, industry, real estate, and telecommunications industries. Together with the structural adjustment of the demand for low-voltage electrical appliances and the potential demand of the international market, it provides a broad space for the future development of the low-voltage electrical appliance industry.
During the "Twelfth Five-Year Plan" period, with the advancement of smart grid construction and the continuous development of low-voltage electrical appliances production technology, a new generation of low-voltage electrical appliances featuring intelligence, modularity, and communication capabilities will become the market Mainstream products. The first-generation products will withdraw from the market in 2010, the second-generation products will become low-end products, and the third-generation products and some second-generation products will become mid-end products. From 2011 to 2015, the smart grid will enter a comprehensive construction stage in seven aspects, including power transmission, transformation, distribution, and communications, and the total investment in smart grid construction will be close to 2 trillion yuan. In early 2011, the State Council decided to implement a new round of rural power grid transformation and upgrading projects. The new round of rural power grid transformation projects will bring important development opportunities to the low-voltage electrical industry.