This specification is formulated to implement the national technical and economic policies in the design of power distribution for electrical equipment, to ensure personal safety, reliable power distribution, advanced technology, economic rationality, energy conservation and convenient installation and maintenance. This specification is applicable to the design of power distribution for general electrical equipment in new and expanded industrial and civil projects. GB 50055-1993 Specification for Power Distribution Design for General Electrical Equipment GB50055-1993 Standard download decompression password: www.bzxz.net

Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
50055-93
Code for design of electric distributionof generalpurposeutilizationequipment
1993-09-14
1994-03-01
State Bureau of Technical Supervision
Ministry of Construction of the People's Republic of China
Engineering Construction Standard Full-text Information System
Jointly Issued
Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
Code for design of electric distributionof generalpurposeutilizationequipment
5005593
Editorial Department Department: Ministry of Machinery Industry of the People's Republic of China Approval Department: Ministry of Construction of the People's Republic of China Effective Date: March 1, 1994
Full Text Information System of Engineering Construction Standards
Full Text Information System of Engineering Construction Standards
Notice on the Issuance of the National Standard "Design Specification for Power Distribution of General Electric Equipment"
Jianbiao [1993] No. 679
According to the requirements of the State Planning Commission's Document No. Jizong [1986] 250, the "Design Specification for Power Distribution of General Electric Equipment" revised by the former Ministry of Machinery and Electronics Industry and relevant departments has been reviewed by relevant departments. The "Design Specification for Power Distribution of General Electric Equipment" GB50055-93 is now approved as a mandatory national standard and will be implemented from March 1, 1994. The former national standard "Design Specification for Power Installations of General Industrial and Civil Equipment" GBJ55-83 will be abolished at the same time.
This standard is managed by the Ministry of Machinery Industry, and its specific interpretation and other work are the responsibility of the Seventh Design Institute of the Ministry of Machinery Industry. The publication and distribution is organized by the Standard and Quota Research Institute of the Ministry of Construction.
Ministry of Construction of the People's Republic of China
September 14, 1993
Engineering Construction Standard Full-text Information System
Engineering Construction Standard Full-text Information System
Revision Notes
This specification is edited by the Ministry of Machinery Industry in accordance with the requirements of the State Planning Commission's Document No. [1986250], and is specifically revised by the Seventh Design Institute of the Ministry of Machinery Industry in conjunction with relevant units from the "Design Specifications for Power Installations for General Industrial and Civilian Equipment" GBJ55-83.
During the revision process, the specification revision group conducted extensive investigations and studies, carefully summarized the experience since the implementation of the specification, absorbed some scientific research results, and widely solicited opinions from relevant units across the country. Finally, our ministry and relevant departments reviewed and finalized the draft. The main contents of this revision are: (1) Added chapters, sections and articles on elevators, escalators, gantry cranes, charging of fixed acid-proof lead-acid batteries and nickel-cadmium batteries, and daily electrical appliances; (2) Clearly formulated relevant safety provisions such as "installation of isolation appliances" and "motor ground fault protection"; (3) Added energy-saving provisions for motors, welding machines, lifting and transportation equipment; (IEC) standards convergence, etc.
(4) To the International Electrotechnical Commission
During the implementation of this specification, if any modification or supplement is found, please send your opinions and relevant materials to the Seventh Design Institute of the Ministry of Machinery Industry (outside Hepingmen, Xi'an, postal code 710054), and copy to the Ministry of Machinery Industry for reference in future revisions. Ministry of Machinery Industry
September 1993
Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
Chapter 1
Chapter 2
Section 1
General Provisions
Section 2
Section 3
Section 4
Section 5
Section 6
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Selection of Motor
Starting of Motor
Protection of Low-voltage Motor
Main Circuit of Low-voltage AC Motor
Low-voltage AC Motor control circuit
Lifting and transportation equipment
Belt conveyor transportation line
Elevator and escalator
Battery charging
Electrostatic filter power supply
Daily electrical appliances
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Terms used in this specification
Additional explanation
Engineering construction standard full text information system
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Engineering construction standard full text information system
Chapter 1 General
Article 1.0.1 This specification is formulated to ensure that the power distribution design of general power equipment implements the national technical and economic policies, ensures personal safety, reliable power distribution, advanced technology, economic rationality, energy conservation and convenient installation and maintenance. Article 1.0.2 This specification applies to the power distribution design of general power equipment in new and expanded industrial and civil projects.
Article 1.0.3 The power distribution design of general-purpose electrical equipment shall adopt products that meet the current national standards and industry standards, and shall adopt products with high efficiency, low energy consumption and advanced performance.
Article 1.0.4
In addition to complying with this specification, the power distribution design of general-purpose electrical equipment shall also comply with the provisions of the current relevant national standards and specifications. Engineering Construction Standard Full-text Information System
Engineering Construction Standard Full-text Information System
Chapter 2 Motors
Section 1 General Provisions
Article 2.1.1 This chapter applies to general-purpose motors with a rated power of 0.55kW and above. Among them, Sections 2 and 3 apply to motors with a rated voltage not exceeding 10kV; Section 4 applies to motors with a rated voltage not exceeding 1000V; Sections 5 and 6 apply to AC motors with a rated voltage not exceeding 1000V. Article 2.1.2 The protection and secondary circuit of 3~10kV asynchronous motors and synchronous motors shall comply with the provisions of the current national standard "Design Specifications for Relay Protection and Automatic Devices of Power Installations".
The selection of switchgear and conductors for 3~10KV asynchronous motors and synchronous motors shall comply with the provisions of the current national standard "Design Specifications for 3~110KV High Voltage Distribution Devices".
Section 2 Selection of Motors
Article 2.2.1 The electrical and mechanical parameters of the motor, such as the duty, rated power, stall torque, minimum torque, maximum torque, speed and its adjustment range, shall meet the requirements of the machine (hereinafter referred to as the machine) driven by the motor under various operating modes.
Article 2.2.2 The selection of motor types shall comply with the following provisions: 1. When the machine has no special requirements for starting, speed regulation and braking, a cage motor shall be used, but for machines with large power and continuous operation, a synchronous motor shall be used when it is technically and economically reasonable.
2. Wound rotor motors should be used when any of the following conditions are met: 1. For machinery that is started under heavy load, when cage-type motors cannot meet the starting requirements or when increasing the power is unreasonable;
Engineering Construction Standards Full-text Information System
Engineering Construction Standards Full-text Information System
2. Machinery with a small speed regulation range and a short low-speed operation time. 3. When the machinery has special requirements for starting, speed regulation and braking, the type of motor and its speed regulation method should be determined based on technical and economic comparisons. When AC motors cannot meet the characteristics required by the machinery, DC motors should be used; emergency units that must work after the AC power supply disappears can also use DC motors. For fans and pumps that operate under variable loads, speed regulation devices should be used when it is technically and economically reasonable, and motors of the corresponding types should be selected. Section 2.2.3. The selection of motor rated power shall comply with the following provisions: 1. Machinery with a continuous working load and a stable load shall use a motor with the maximum continuous rating, and its rated power shall be selected according to the shaft power of the machinery. When the machinery is started under heavy load, the rated power of the cage motor and the synchronous motor shall be verified according to the starting conditions. For the synchronous motor, its pull-in torque shall also be verified.
2. Machinery with short-time working shall use a motor with a short-time rating, and its rated power shall be selected according to the shaft power of the machinery: When there is no short-time rated motor of suitable specifications, a motor with a cycle working rating may be selected according to the allowable overload torque. 3. Machinery with intermittent cycle working shall use a motor with a corresponding cycle working rating, and its rated power shall be selected according to the allowable output power under different load duration rates and different starting times provided by the manufacturer, or it may be selected according to the equivalent load of the typical cycle converted into the rated load duration rate, and shall be verified according to the allowable overload torque. 4. Machinery with continuous load cycles should use motors with corresponding cycle duty ratings. The rated power should be selected according to the data provided by the manufacturer. It can also be selected by the equivalent current method or the equivalent torque method, and should be checked according to the allowable overload torque. 5. When selecting the rated power of the motor, an appropriate reserve factor should be taken into account according to the type and importance of the machinery.
6. When the altitude and cooling medium temperature of the motor use site are different from the specified working conditions, its rated power should be corrected according to the manufacturer's data. Article 2.2.4 The rated voltage of the motor should be selected according to its rated power and the distribution voltage of the system in which it is located. If necessary, it should be determined based on technical and economic comparisons. Article 2.2.5 The protection type of the motor should comply with the environmental conditions of the installation site. Engineering Construction Standard Full Text Information System
Engineering Construction Standard Full Text Information System
Article 2.2.6 The structure and installation type of the motor should be compatible with the machinery. Section 3 Starting of Motors
Article 2.3.1 When the motor is started, its terminal voltage should be able to ensure the starting torque required by the machine, and the voltage fluctuation caused in the distribution system should not hinder the operation of other electrical equipment.
Article 2.3.2 When the AC motor is started, the voltage on the distribution bus should comply with the following provisions:
, Under normal circumstances, when the motor is started frequently, it should not be lower than 90% of the rated voltage, and when the motor is not started frequently, it should not be lower than 85% of the rated voltage. 2. When there is no lighting or other load that is sensitive to voltage fluctuations on the distribution bus, and when the motor is not started frequently, it should not be lower than 80% of the rated voltage. 3. When there is no other electrical equipment connected to the distribution bus, it can be determined according to the conditions for ensuring the starting torque of the motor. For low-voltage motors, it should also be ensured that the voltage of the contactor coil is not lower than the release voltage.
Article 2.3.3 The selection of starting methods for cage-type motors and synchronous motors shall comply with the following provisions:
1. When the following conditions are met, the motor shall be started at full voltage: 1. When the motor is started, the voltage of the distribution bus shall comply with the provisions of Article 2.3.2 of this specification:
2. The machine can withstand the impact torque when the motor is started at full voltage; 3. The manufacturer has no special regulations on the starting method of the motor. 2. When the conditions for full-voltage starting are not met, the motor should be started at reduced voltage, or other appropriate starting methods should be selected.
3. When there is a speed regulation requirement, the starting method of the motor should be coordinated with the speed regulation method.
Article 2.3.4 Wound rotor motors should be started by connecting a frequency-sensitive rheostat or resistor in the rotor circuit, and should meet the following requirements: Engineering Construction Standard Full Text Information System
Engineering Construction Standard Full Text Information System
1. The average starting current should not exceed 2 times the rated current of the motor or the value specified by the manufacturer;
2. The starting torque should meet the requirements of the machinery; 3. When there is a speed regulation requirement, the starting method of the motor should be coordinated with the speed regulation method.
Article 2.3.5 DC motors should be started by adjusting the power supply voltage or reducing the voltage with a resistor, and should meet the following requirements:
1. The starting current should not exceed 1.5 times the rated current of the motor or the value specified by the manufacturer;
2. The starting torque and speed regulation characteristics should meet the requirements of the machinery. Section 4 Protection of Low-voltage MotorsbzxZ.net
Article 2.4.1 AC motors shall be equipped with short-circuit protection and ground fault protection, and shall be equipped with overload protection, phase failure protection and low voltage protection according to specific circumstances. Synchronous motors shall also be equipped with out-of-step protection.
Article 2.4.2 Each AC motor shall be equipped with phase-to-phase short-circuit protection, but several AC motors may share a set of short-circuit protection devices if one of the following conditions is met:
1. The total calculated current does not exceed 20A and is allowed to be cut off without selection; 2. According to process requirements, a group of motors must be started and stopped at the same time, and if they are not cut off at the same time, it will endanger the safety of personnel and equipment.
Article 2.4.3 The short-circuit protection device of AC motors should be a fuse or an instantaneous overcurrent release of a low-voltage circuit breaker: If necessary, an overcurrent relay with an instantaneous element may be used. The installation of protection devices shall comply with the following provisions: 1. When short-circuit protection also serves as ground fault protection, it shall be installed on each ungrounded phase line.
2. When only for phase-to-phase short-circuit protection, the fuse should be installed on each ungrounded phase line, and the overcurrent release or relay should be installed on at least two phases. 3. When installed on only two phases, in the same network with direct electrical connection, the protection device should be installed on the same two phases. Article 2.4.4 When the AC motor is operating normally, starting normally or self-starting, the short-circuit protection device should not malfunction. To this end, the following provisions should be met: 1. Correctly select the use category of protective electrical appliances; fuses, low-voltage circuit breakers and overcurrent relays should be motor protection types. 2. The rated current of the fuse should be greater than the rated current of the motor, and its Amway characteristic curve should be slightly higher than the intersection of the motor starting current and starting time after taking into account the deviation. When the motor is frequently started and braked, the rated current of the fuse should be increased by 1 to 2 levels.
3. The setting current of the instantaneous overcurrent release or the instantaneous element of the overcurrent relay should be 2 to 2.5 times the starting current of the motor. Article 2.4.5 The ground fault protection of AC motors shall comply with the following provisions: 1. Each motor shall be equipped with ground fault protection, but several motors that share a set of short-circuit protection devices can share a set of ground fault protection devices. 2. Ground fault protection shall comply with the provisions of the current national standard "Low Voltage Distribution Design Specifications".
3. When the short-circuit protection device of the motor meets the ground fault protection requirements, short-circuit protection should be used as ground fault protection. Article 2.4.6 The installation of overload protection for AC motors shall comply with the following provisions: 1. Motors that are easily overloaded during operation, motors that are difficult to start or self-start and require limited starting time, should be equipped with overload protection. Continuously running motors with a rated power greater than 3KW should be equipped with overload protection; but when the loss caused by power failure is greater than the overload, it is not appropriate to install overload protection, or make the overload protection action hand signal. 2. Motors that work in short time or intermittent cycle may not be equipped with overload protection. When the motor may be blocked during operation, an overload protection to protect the motor from blocking should be installed.
Article 2.4.7 The action characteristics of the overload protection device of the AC motor should match the overload characteristics of the motor. The overload protection device should adopt a thermal overload relay (hereinafter referred to as the thermal relay) or an overload release with inverse time characteristics, or an inverse time overcurrent relay. When conditions permit, temperature protection or other appropriate protection can be used. Article 2.4.8 When the AC motor is operating normally, starting normally or starting automatically, the overload protection device should not malfunction and should comply with the following provisions: 1. The setting current of the thermal relay or overload release should be close to but not less than the rated current of the motor.
2. The action time limit of the overload protection should avoid the normal starting or self-starting time of the motor. The setting current of the overcurrent relay should be determined by the following formula: Ied
Iu= KkKKgn
In the formula, Iad
The setting current of the overcurrent relay (A); Iea
The rated current of the motor (A);
K is the reliability coefficient, which is 1.2 when it is powered off and 1.05 when it is signaled;
is the connection coefficient, which is 1.0 when it is connected to the phase current and 3 when it is connected to the phase current difference;
K is the relay return coefficient, which is 0.85;
n is the current transformer ratio.
3. If necessary, the overload protection device can be short-circuited or removed within a certain time limit during the starting process.
Section 2.4.Article 9 The phase-failure protection of AC motors shall comply with the following provisions: 1. For continuously running three-phase motors, when fuse protection is adopted, phase-failure protection shall be installed; when low-voltage circuit breakers are adopted for protection, phase-failure protection should be installed; when low-voltage circuit breakers are also used as motor control devices, phase-failure protection may not be installed. 2. Motors that work in short periods of time or intermittent cycles or motors with a rated power not exceeding 3KW may not be equipped with phase-failure protection. 3. Phase-failure protection devices should adopt phase-failure protection thermal relays, and temperature protection or special phase-failure protection devices may also be used.
Article 2.4.10 The low-voltage protection of AC motors shall comply with the following provisions: 1. Motors that are not allowed to start automatically according to process or safety conditions or to ensure the construction of important projects Standard Full Text Information System
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