Low-voltage electrical industry: foreign brands: ABB Schneider, Rogeland, Siemens, etc.; domestic brands: Noack, Chint, Liangxin, Danko, Boer, San-Xin International, etc.

With the rapid development of microcomputer technology, microelectronic technology, computer network and digital communication technology, and the application of artificial intelligence technology in low-voltage electrical appliances, intelligent electrical appliances will develop from a single enclosed device that simply uses microcomputer control to replace traditional relay functions to an intelligent system with a complete theoretical system and multidisciplinary intersection, becoming a major part of the electrical engineering field of power switchgear, power systems, relay protection, industrial supply and distribution systems and industrial control networks. It will become the new development direction of electrical switchgear, relay protection, industrial supply and distribution system and industrial control network technology.

1、The current situation of circuit breakers

In the low-voltage transmission and distribution network, the molded case circuit breaker is one of the important basic components, for those who often occur in the overload of electrical equipment, short-circuit occasions, can safely and reliably cut off the fault current, to prevent the accident from expanding to endanger the entire transmission and distribution system. Foreign companies such as ABB, Siemens and Schneider have already launched a new generation of products, and some famous domestic electrical enterprises have also formed the fourth generation of plastic case circuit breakers in the field of low-voltage electrical appliances. The main technical features of the new generation are: high performance contact interrupter system, modular structure, electronic decoupler, superior performance, easy installation, communication with fieldbus, etc.

1.1 High-performance contact arcing system ABB, Schneider, GE and most other European and American companies use a new generation of products with double-breakpoint rotary contact system, which strengthens the short arc near the cathode effect, has a higher arc voltage to improve the breaking capacity, and eliminates the need for soft connections. Some domestic companies have applied for patents on double-breakpoint rotating contacts, such as the invention patent applied for by Zhejiang Chint Electric Co. The invention uses a relatively simple structure to achieve a reliable mechanical connection and transmission between the single-pole units; at the same time, it makes the installation more flexible and convenient, simplifying the assembly process and reducing manufacturing costs.

1.2 The use of electronic decoupling electronic decoupling is a combination of microelectronics, computers and communications technology, with the traditional thermal magnetic decoupling incomparable advantages. For example: the release characteristics are stable, not affected by the ambient temperature and climate; high accuracy of the release current and time; adjustable setting current, and can set different characteristic curves to adapt to the requirements of various load protection; electronic release can be derived from the communication function, to achieve network control, can also be derived from the regional interlock, power monitoring and power analysis and other auxiliary functions. A new generation of moulded case circuit breakers from various companies can be fitted with electronic decouplers, and are gradually being developed for smaller rated current frames of 160A and below.

The SACEIsomaxS low-voltage moulded-case circuit breaker from ABB uses a microprocessor electronic decoupler, a breaking method and specially shaped breaking elements that enable the breaker to break short-circuit currents of up to 200 kA in a very short time.

1.3 Communication with the fieldbus The global power and control specialist Schneider has launched the MT, MVV and MTE series of frame circuit breakers on the basis of the M series. The products have a reduced profile, a complete range of protection functions, an intelligent controller that adds voltage, frequency and power measurement, calculation of harmonics and fundamental waves, precise analysis of grid quality, and the ability to connect to a wide range of buses. The double rotary interrupting system with high current limiting capacity up to 100 kA, short-circuit protection and overload protection, provides enhanced support for OEM customers and equipment exports.

1.4 Modular structure Currently, the Tianshui GS-3 series intelligent controller is the core control element for intelligent frame type circuit breakers. It can display the operating current and voltage of the equipment or the grid (with voltage display), and according to the size of the load current to achieve various protection, so that the line and power supply equipment from overload, short circuit, grounding and other fault hazards. The control circuit is interrupted in the agreed protection mode. High accuracy and reliability, as well as auxiliary functions such as load monitoring, fault alarm, fault enquiry, online test, field programming and password devices.

Siemens has launched a new generation of its SENTRONWL/VL circuit breaker series, the SENTRONWL universal circuit breaker with a rated current of 630 to 6300 A and the SENTRONVL moulded case circuit breaker with a rated current of 160 to 1600 A. Although the two products have different functions and do not have exactly the same access to the network, they use the same communication protocol and The two products have the same functions and the same access to the network, but they use the same communication protocol and device description, have a variety of bus interfaces such as ProfiBCS DP, Ether net, RS 232C, etc.; through the COM15 module, the WL can be connected to the ProfiBUS network with two features.

2、The development trend of low-voltage electrical appliances in China

With the emergence of new technologies including modern design technology, microelectronics, computer technology, computer network technology, communication technology, intelligent technology, reliability technology, testing technology and new technologies, such as the future of low-voltage electrical appliances in technology and function will have great development, various relays, contactors and circuit breakers are commonly used in electronic and intelligent control. With the rapid development of microcomputer technology, microelectronics, computer networks and digital communication technology, as well as the application of artificial intelligence technology in low-voltage electrical appliances, intelligent electrical appliances will evolve from a single enclosed device that simply uses microcomputer control to replace the function of traditional relays to an intelligent system with a complete theoretical system and multidisciplinary intersection, becoming a key component of electrical switchgear, power systems, industrial supply and distribution systems in the field of electrical engineering. It will become a new development direction for electrical switchgear, relay protection, industrial supply and distribution systems and industrial control network technology.