This specification is applicable to the design of newly built electric heating devices such as electric arc furnaces, ore-heating furnaces, induction furnaces, induction heaters and resistance furnaces. GB 50056-1993 Design Specification for Electric Heating Equipment and Power Installations GB50056-1993 Standard download decompression password: www.bzxz.net

Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
50056—93
Code for design electrical equiment ofelectroheatinstallations
1993-07-05
1994-02-01
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 electrical equiment ofelectroheatinstallations
GB50056-93
Editor Department: China 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: February 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 Specifications for Electric Heating Equipment and Power Installations"
Jianbiao [1993] No. 513
According to the requirements of the State Planning Commission's Document No. Jizong [1986] 250, the "Design Specifications for Electric Heating Equipment and Power Installations" revised by the former Ministry of Machinery and Electronics Industry and relevant departments has been reviewed by relevant departments. The "Design Specifications for Electric Heating Equipment and Power Installations" GB50056-93 is now approved as a mandatory national standard and will be implemented from February 1, 1994. The former national standard "Design Specifications for Electric Heating Equipment and Power Installations" GBJ5683 is abolished at the same time. The Ministry of Machinery Industry is responsible for the management of this standard, and its specific interpretation and other work are the responsibility of the Design Institute of the Ministry of Machinery. 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
July 5, 1993
Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
Revision
This specification is compiled by our department in accordance with the requirements of Document No. 250 of the State Planning Commission [1986], and is edited by our department. Specifically, our department's design institute is the editor-in-chief, and the revision group is organized to revise and compile the original specification.
In the process of revising and compiling this specification, the revision group conducted a large amount of investigation, research, test verification, and widely solicited opinions and letters from relevant units and individuals across the country. Finally, our department and relevant departments reviewed and finalized the draft.
This specification is divided into seven chapters and two appendices. The main contents include general provisions, basic regulations, main circuit systems, equipment selection and layout, protection, control, signal and measurement of arc furnaces, ore-fired furnaces and power frequency, medium frequency, high frequency induction heating devices and resistance furnaces. During the implementation of this specification, if any modification or supplement is found, please send your opinions and relevant information to the Design and Research Institute of the Ministry of Machinery Industry (No. 277 Wangfujing Street, Beijing, Postal Code 100740) for reference in future revisions. Ministry of Machinery Industry
May 1993
Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
Chapter 1
Chapter 2
Chapter 3
Basic Provisions
Electric Arc Furnace and Submerged Arc Furnace Installations,
Section 1
Section 2
Section 3
Section 4
Section 5
Section 6
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Appendix 1
Appendix 2
Main Circuit System of Electric Furnace Installations
Protection and Control , Signal and Measurement
Layout of Power Equipment
Electromagnetic Stirring Device
External Refining Device
Power Frequency Induction Heating Device
Medium Frequency Induction Heating Device
High Frequency Induction Heating Device
Terms Used in This Code
Engineering Construction Standard Full Text Information System
Zhong 9(14)
Engineering Construction Standard Full Text Information System
Chapter 1 General
Article 1.0.1
In order to implement the national technical and economic policies for the design of electric heating equipment and power devices (hereinafter referred to as electric heating devices), and to achieve advanced technology, safety and reliability, energy conservation, economic rationality and easy maintenance, this code is formulated. Article 1.0.2 This code applies to the design of newly built electric heating devices such as electric arc furnaces, ore-heating furnaces, induction furnaces, induction heaters and resistance furnaces. Article 1.0.3 In addition to complying with the provisions of this code, the design of electric heating devices shall also comply with the provisions of the current relevant national standards and specifications. Engineering Construction Standards Full-text Information System
Engineering Construction Standards Full-text Information System
Chapter II Basic Provisions
Article 2.0.1 Electric heating devices should be classified as secondary or tertiary loads. When an accidental power outage will cause significant losses to the national economy, multiple large electric heating devices should be classified as primary loads.
The load level of the auxiliary equipment of the electric heating device should be determined according to the degree of loss or impact caused by the accidental power outage.
Article 2.0.2 The distance between the transformer, frequency conversion or current conversion device of the electric heating device and the electric furnace or heater should be small, but it should be easy to operate, maintain and overhaul. Article 2.0.3 The electric heating device should be equipped with an interlocking device that can meet the requirements of maintenance safety and correct operation.
Article 2.0.4
The relay protection devices, measuring instruments, control devices and wires of the electric heating device should be set up to facilitate operation, monitoring and maintenance, and should avoid heat, moisture, electromagnetic induction, impact and dust accumulation. Article 2.0.5 The cross-section selection and arrangement of high-frequency, medium-frequency current or industrial frequency large current conductors should reduce the uneven distribution of current in the conductors caused by skin effect and neighboring interference effect.
Article 2.0.6 The setting and material selection of the brackets, protective shields, sleeves, armor, fasteners and adjacent metal parts of the conductors of the electric heating device should reduce the influence of induction heating when the frequency is high or the current is large. Article 2.0.7 The configuration of the short network of the electric heating device should have small resistance and reactance, and the three-phase impedance should be balanced.
Article 2.0.8 For electric heating devices with a single power equal to or greater than 400kW, when the natural power factor is low, a separate reactive power compensation device shall be installed. If centralized compensation is advantageous after technical and economic comparison or when the reactive power of the factory or workshop is abundant, a separate compensation device may not be installed.
Engineering Construction Standard Full Text Information System
Engineering Construction Standard Full Text Information System
Article 2.0.9 When the reactive power compensation device of the electric heating device adopts power capacitors, the selection of its performance and the wiring method shall take into account the changes in reactive load and the influence of higher harmonics.
Article 2.0.10 The electric heating device should adopt closed-circuit cooling, and bubbles shall not be generated in the closed-circuit system.
Article 2.0.11 The setting of the cooling water system of the electric heating device shall be convenient for monitoring its working condition, and water temperature, water pressure, flow rate and other signals and protection devices shall be installed as needed. When necessary, safety measures such as disconnecting the power supply of the electric heating device shall be taken. Article 2.0.12 The inner diameter and length of the insulating water pipe connecting the water-cooled power frequency conductor and the metal water supply and drainage pipe should be selected so that the leakage current of the water in each insulating water pipe does not exceed 20mA or other safety measures are taken. Article 2.0.13 Multiple single-phase electric heating devices should be evenly connected to the three-phase circuit. Article 2.0.14 When the capacity of the single-phase electric heating device is large, the impact of the negative sequence current and negative sequence voltage caused by the electric heating device on the power grid should be verified: when it exceeds the allowable value of the current national standard, the single-phase load should be connected to the power grid point with a larger short-circuit capacity or a phase balancing device should be installed. When imbalance does not often occur during operation, a switching device that can switch single-phase loads between three-phase power grids should be installed. When the process allows the use of DC heating, the single-phase load can be rectified by three-phase AC and powered by DC. Article 2.0.15 Electric heating devices with large unbalanced currents or transformers (distribution) with more single-phase electric heating loads should be equipped with instruments to monitor negative sequence currents. Article 2.0.16 The non-sinusoidal distortion of the public grid voltage waveform caused by the electric load of the electric heating device shall not exceed the requirements of the current national standards. When the requirements cannot be met, measures such as installing harmonic filtering devices shall be taken. Article 2.0.17 The minimum distance between the protruding parts of the electric furnace transformer below 1.9m above the ground of the transformer room and the indoor wall of the transformer room shall comply with the provisions of Table 2.0.17.
Engineering Construction Standard Full Text Information System
Engineering Construction Standard Full Text Information System
Minimum distance between the electric furnace transformer and the indoor wall (m) Table 2.0.17
Electric furnace transformer capacity (MVA)
Front wall (near the electric furnace)
Side wall and rear wall
Article 2.0.Article 18
For the insulating supports of busbars or busbar groups and the linings between busbars in electric heating devices, in circuits with DC or AC power frequency, low frequency and medium frequency less than V, asbestos cement boards (blocks) treated with insulation impregnation can be used: when the voltage is less than 500V, impregnated wood (impregnated in dry oil) can also be used. When the voltage is greater than 1kV and less than 1.6kV, bakelite, glass fiber board or heat-resistant plastic should be used. The insulating supports (clamping block linings) of electric furnaces with rapidly changing impact loads should be made of earthquake-resistant materials.
For voltages greater than and equal to 1.6kV, post insulators made of porcelain or glass should be used. When the power frequency current is greater than and equal to 1.5kA and any current value of medium frequency and high frequency, the accessories of the insulator should be made of aluminum. When protected by aluminum shielding or made of less magnetic pig iron, the accessories of the insulator can be made of cast iron.
When the power frequency current is greater than or equal to 1.5kA and any current value of medium frequency and high frequency, the metal parts clamped by the busbar group should be made of non-magnetic steel plates with curved side sections or welded side sections and silicon aluminum alloy parts, except for heavy multi-piece busbar groups. The fasteners of large current busbars should be bolts and studs made of non-magnetic chromium-nickel, copper-zinc or other alloys.
Article 2.0.19 The insulation resistance between the busbars of different poles (different phases) of the secondary conductor busbar group of the electric heating device transformer shall meet the product requirements. When the product requirements do not specify the insulation resistance value, the insulation resistance between the busbars of different poles (different phases) of the busbar group shall comply with the provisions of Table 2.0.19.
Engineering Construction Standard Full Text Information System
Engineering Construction Standard Full Text Information System
Insulation resistance between buses of different poles (different phases) of busbar group
Voltage (KV)
Table 2.0.19
Note: The insulation resistance is measured by using a megohmmeter with a voltage of 2.5kV, and the outlet terminals of the conductor and transformer, frequency converter, switchgear, resistance furnace heating element, etc. are disconnected, the furnace electrode is lifted, and the hose of the water cooling system is disassembled before measurement. Article 2.0.20
The minimum clearance between buses of different poles (different phases) of AC or DC secondary hard conductors shall comply with the provisions of Table 2.0.20. Article 2.0.21
For the parts of the electric heating device that need to be maintained at a height of 2m or more from the installation ground, a platform with a guardrail and a fixed ladder should be provided. Movable ladders shall not be used. In the area where maintenance personnel may touch the live parts of the device, the platform, guardrail and ladder shall be made of flame-retardant materials, and the walkway board of the working platform shall be covered with flame-retardant insulating materials.
Article 2.0.22
For the potential pump and oil filling device of the hydraulic system of the electric heating equipment, when the oil volume is 60kg or more, accident oil discharge facilities shall be provided. Article 2.0.23
For static electricity that endangers the safety of workers or the normal operation of the electric heating device, suppression measures such as grounding, shielding or providing sufficient distance shall be taken. Engineering Construction Standard Full Text Information System
Engineering Construction Standard Full Text Information System
Conductor Installation
Dry, Dust-freewwW.bzxz.Net
Dry, Dust-free
Minimum Clearance Between Secondary Hard Conductor Busbars (mm) Current
30~150
500~10000Hz
Note: ①The above table refers to busbar height of less than 250mm. When it is higher than this value, the minimum clearance should be increased by 5~10mm. ②Dusty refers to non-conductive dust.
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Table 2.0.20
>1000Hz
30~140
35~150
Engineering Construction Standard Information System
Chapter 3 Electric Arc Furnace and Submerged Arc Furnace Installations
Main Circuit System of Electric Furnace Installations
Section 1
Article 3.1.1 Electric furnaces shall be equipped with special transformers connected to the power supply system. The capacity of the electric furnace transformer shall be selected in accordance with the power consumption system specified in the process and the allowable overload capacity of the transformer. Its secondary voltage and voltage regulation method shall meet the requirements of the process. The selection of its primary voltage shall be determined based on the technical and economic comparison of the power supply. Article 3.1.2 The power supply system of the electric furnace shall be simple and easy to operate. A single electric furnace installation should be powered by a single circuit. The electric furnace substation should not be connected to the high-voltage line for external power supply.
Article 3.1.3 The voltage fluctuation value of the power supply bus caused by the working short circuit of the three-phase electric arc furnace should not exceed 2.5%, but the voltage fluctuation of the secondary bus of the substation dedicated to the electric arc furnace should not be subject to this restriction. When the above requirements cannot be met, measures such as connecting the electric arc furnace to a grid point with a larger short-circuit capacity should be taken to reduce the voltage fluctuation. Article 3.1.4 For electric furnace devices with working short circuits, measures should be taken to limit the working short-circuit current within the allowable range of electrical equipment. The working short-circuit current of the three-phase electric arc furnace device should not be greater than 3.5 times the rated current of the electric furnace transformer. When a reactor is used to limit the short-circuit current, the reactor should be equipped with a bypass switch. Article 3.1.5 The current carrying capacity of the conductor of the main circuit system of the three-phase electric arc furnace device should be calculated as 120% of the rated capacity of the transformer; the rated current of the switchgear and transformer can be selected as greater than 120%.
Article 3.1.6 The three-phase electric arc furnace device should use an operating circuit breaker with frequent operation performance.
Article 3.1.7 Arc furnace and ore-heat furnace transformers shall adopt the following measures to limit operating overvoltage:
Engineering Construction Standard Full Text Information System20
>1000Hz
30~140
35~150
Engineering Construction Standard Full Text Information System
Chapter 3 Electric Arc Furnace and Submerged Arc Furnace Installations
Main Circuit System of Electric Furnace Installations
Section 1
Article 3.1.1 Electric furnaces shall be equipped with special transformers connected to the power supply system. The capacity selection of electric furnace transformers shall comply with the power consumption system stipulated in the process and the allowable overload capacity of the transformer. Its secondary voltage and voltage regulation method shall comply with the requirements of the process. The selection of its primary voltage shall be determined based on the technical and economic comparison of power supply. Article 3.1.2 The power supply system of electric furnaces shall be simple and easy to operate. A single electric furnace installation should be powered by a single circuit. The electric furnace substation should not be connected to high-voltage lines for external power supply.
Article 3.1.3 The voltage fluctuation value of the power supply bus caused by the working short circuit of the three-phase electric arc furnace should not exceed 2.5%, but the voltage fluctuation of the secondary bus of the substation dedicated to the electric arc furnace should not be subject to this restriction. When the above requirements cannot be met, measures such as connecting the electric arc furnace to a grid point with a larger short-circuit capacity should be taken to reduce the voltage fluctuation. Article 3.1.4 For electric furnace devices with working short circuits, measures should be taken to limit the working short-circuit current within the allowable range of electrical equipment. The working short-circuit current of the three-phase electric arc furnace device should not be greater than 3.5 times the rated current of the electric furnace transformer. When a reactor is used to limit the short-circuit current, the reactor should be equipped with a bypass switch. Article 3.1.5 The current carrying capacity of the conductor of the main circuit system of the three-phase electric arc furnace device should be calculated as 120% of the rated capacity of the transformer; the rated current of the switchgear and transformer can be selected as greater than 120%.
Article 3.1.6 The three-phase electric arc furnace device should use an operating circuit breaker with frequent operation performance.
Article 3.1.7 Arc furnace and ore-heat furnace transformers shall adopt the following measures to limit operating overvoltage:
Engineering Construction Standard Full Text Information System20
>1000Hz
30~140
35~150
Engineering Construction Standard Full Text Information System
Chapter 3 Electric Arc Furnace and Submerged Arc Furnace Installations
Main Circuit System of Electric Furnace Installations
Section 1
Article 3.1.1 Electric furnaces shall be equipped with special transformers connected to the power supply system. The capacity selection of electric furnace transformers shall comply with the power consumption system stipulated in the process and the allowable overload capacity of the transformer. Its secondary voltage and voltage regulation method shall comply with the requirements of the process. The selection of its primary voltage shall be determined based on the technical and economic comparison of power supply. Article 3.1.2 The power supply system of electric furnaces shall be simple and easy to operate. A single electric furnace installation should be powered by a single circuit. The electric furnace substation should not be connected to high-voltage lines for external power supply.
Article 3.1.3 The voltage fluctuation value of the power supply bus caused by the working short circuit of the three-phase electric arc furnace should not exceed 2.5%, but the voltage fluctuation of the secondary bus of the substation dedicated to the electric arc furnace should not be subject to this restriction. When the above requirements cannot be met, measures such as connecting the electric arc furnace to a grid point with a larger short-circuit capacity should be taken to reduce the voltage fluctuation. Article 3.1.4 For electric furnace devices with working short circuits, measures should be taken to limit the working short-circuit current within the allowable range of electrical equipment. The working short-circuit current of the three-phase electric arc furnace device should not be greater than 3.5 times the rated current of the electric furnace transformer. When a reactor is used to limit the short-circuit current, the reactor should be equipped with a bypass switch. Article 3.1.5 The current carrying capacity of the conductor of the main circuit system of the three-phase electric arc furnace device should be calculated as 120% of the rated capacity of the transformer; the rated current of the switchgear and transformer can be selected as greater than 120%.
Article 3.1.6 The three-phase electric arc furnace device should use an operating circuit breaker with frequent operation performance.
Article 3.1.7 Arc furnace and ore-heat furnace transformers shall adopt the following measures to limit operating overvoltage:
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