Safety, Intelligence, and DC Electrical Appliances: What Has Changed in the 2020 New National Standards for Low-Voltage Electrical Appliances
Safety, Intelligence, and DC Electrical Appliances: What Has Changed in the 2020 New National Standards for Low-Voltage Electrical Appliances
Safety, Intelligence, and DC Electrical Appliances: What Has Changed in the 2020 New National Standards for Low-Voltage Electrical Appliances
In April 2021, two highly significant new standards in the low-voltage electrical industry officially came into force: GB/T 14048.2-2020 Low-voltage switchgear and controlgear—Part 2: Circuit-breakers and GB/T 14048.4-2020 Low-voltage switchgear and controlgear—Part 4-1: Contactors and motor-starters—Electromechanical contactors and motor-starters (including motor protectors). Circuit breakers and contactors are the two most widely used and functionally important types of switching devices. This round of standard updates is quite different from previous revisions that mainly focused on detailed improvements and minor modifications. It reflects new changes and trends in the mature low-voltage electrical industry, mainly in three areas: safety, intelligence, and DC electrical appliances.
Safety
As society and the economy continue to develop, requirements for personal and equipment safety are also increasing. Since power supply is an indispensable part of modern life, its safety is becoming ever more important for both production and daily living. In the 2020 new national standards, greater emphasis is placed on using devices that respond to residual current as part of the protective system, in order to provide protection against electric shock hazards. Standards related to the use, testing, and inspection of circuit breakers with residual current protection (CBR) have also been supplemented and updated in the new GB/T 14048.2 standard.
In GB/T 14048.4, new safety-related requirements have also been added, including general requirements, limited-energy circuits, electronic circuits, and electromechanical overload protection circuits for safety locations.
Intelligence
The impact of the industrial internet on traditional industries is obvious, and traditional industries must actively adapt to these changes. For standards-setting organizations, however, it is not always easy to respond quickly. Even so, the new standards clearly show how intelligent functions are influencing traditional switching devices. GB/T 14048.2 adds requirements for digital inputs and outputs with programmable logic controllers (PLCs), formally incorporating PLC-related content into low-voltage electrical standards and marking a meaningful step toward smarter electrical equipment. GB/T 14048.4 goes even further by adding load monitoring requirements, formally writing into the national standard the need to monitor load conditions for functions such as energy efficiency monitoring and asset management in the industrial internet context.
DC Electrical Appliances
With the rise of new energy industries such as photovoltaic power generation, wind power, and electric vehicles, DC electrical appliances are receiving increasing attention. The new GB/T 14048.2 includes extensive additions on the manufacture, use, and testing of DC switching devices, including content such as DC circuit breakers for photovoltaic applications and critical DC load current tests. GB/T 14048.4 also adds DC requirements related to photovoltaic applications, including provisions and requirements for DC contactors below 1500 V.
Other Changes
In addition to the changes mentioned above, the new GB/T 14048.2 and GB/T 14048.4 standards also include a number of timely refinements and supplementary details, mainly as follows:
GB/T 14048.2
- The upper limit of AC voltage within the scope has been expanded to not more than 1500 V.
- Supplementary provisions have been added for rated values above AC 1000 V but not exceeding 1500 V, including impulse withstand voltage, electrical clearances, dielectric tests, and related requirements (see 7.1.4, 7.2.3.2, and 8.4.6).
- For glow-wire testing of materials, the test temperature for insulating materials used to fix current-carrying parts has been clarified: 960°C for the main circuit and 850°C for other circuits.
- The temperature-rise requirement in 7.2.2.3 Main circuit has been revised: the current to be withstood has been changed from the conventional free-air thermal current to the rated current In.
- In 8.3.1 Test procedure, optional test procedures for AC circuit breakers with different numbers of poles have been added, along with new Tables 9b and 9c.
- 8.5 Special tests—damp heat, salt mist, vibration, and shock has been added.
- In Annex A, the content of A.5 Verification of selectivity has been refined, adding provisions and requirements for both theoretical study of selectivity and determination of selectivity through testing.
- In Annex B and Annex M, requirements and test methods for Type B CBR and Type B MRCD have been added.
- In Annexes B, F, and J, relevant EMC performance requirements have been updated.
- New Annex D (normative): Special requirements for circuit breakers intended for connection with aluminum conductors has been added.
- New Annex P (normative): DC circuit breakers for photovoltaic applications has been added.
- New Annex R (normative): Residual current protective circuit breakers with automatic reclosing function has been added.
GB/T 14048.4
- The definition of a reversing starter has been revised.
- Requirements and tests related to motor protective switching devices (MPSD) have been added.
- To accommodate the operating conditions of motors with higher energy-efficiency classes, provisions related to high locked-rotor current have been added.
- Requirements for dedicated wiring accessories have been added.
- Measurement of pick-up power consumption has been added.
- Coordination requirements under short-circuit conditions between MPSD and other short-circuit protective devices in the same circuit have been added (see Annex Q).
- The former Annex J on the communication functions of electronic overload relays has been deleted.
Testing and Inspection
The updating of standards places new requirements on manufacturers, and compliance must be verified through updated testing and inspection methods and equipment to ensure that products meet the new standards. Based on the release and revision of these standards, and drawing on extensive experience and technical capabilities in the testing and inspection industry, our company provides testing equipment and systems that meet the requirements of the new national standards, helping customers ensure that their products comply with the latest regulations. In response to the updated standards, we have upgraded a number of testing products and equipment. We also provide complete testing systems and laboratory solutions for electrical life, mechanical life, temperature rise and tripping, short circuit, and other related tests. In addition, we offer outsourced operation, maintenance, and upgrading services for laboratory equipment, as well as laboratory digitalization and management systems. Please feel free to contact us at 400-029-9162.
1. CBR Testing System for Residual Current Protective Circuit Breakers
- Operating characteristic tests under residual current conditions
- Rated residual short-circuit making and breaking capacity tests
- Operational performance tests
- Dielectric performance tests
- CBR test simulation devices
- Anti-maloperation tripping tests under capacitive loads
- Sinusoidal AC residual current tests at high frequency (1000 Hz) and below
- AC/DC mixed residual current tests
- Smooth DC residual current tests
- CBR time-delay operation tests
- Temperature-rise limit tests
- Supply voltage fault operation tests
- Low-impedance earth fault and phase-loss tests
- Visual-recognition-based appearance inspection tests
2. MPSD Testing System for Motor Protectors
- Short-circuit characteristic tests
- Making and breaking capacity tests
- Conventional operational performance tests
- Coordination operating characteristic tests with short-circuit protective devices
- Visual-recognition-based appearance inspection tests
3. Critical DC Load Current Test System
- For critical DC load current tests of DC circuit breakers and contactors
- Fully automatic arc duration measurement and comparison
- Fully automatic load voltage and current adjustment
4. DC Contactor Testing System
- DC contactor operational performance test system
- DC contactor temperature-rise test system
- DC contactor short-circuit coordination test system
- DC contactor reliability testing system
