GB 50056-93.The title is CODE FOR DESIGN OF ELECTRICAL EQUIPMENT OF ELECTROHEAT INSTALLATIONS.
This book is the English translation of Code for Design of electrical equipment of electroheat installations GB50056 — 93. It is the official translation of the original in Chinese for general use as examined and approved by the Department of Standards and Norms, Ministry of Construction of the People’s Republic of China.
In the event of any inconsistency between the Chinese-language text of the Standard and the present English-language text of the Standard, the Chineselanguage text shall be taken as ruling.
1.0.1 The object of this code in to promote the design of electrical equipment of electroheat installations must be according with the state economic technical policy. Advanced technique, safety of person, saving electrical energy, rational economy and maintain easily must be realized.
1.0.2 This code apply to the design of new industrical electroheat installations
sucn as:
— direct arc furnaces.
— submerged arc furnaces,
— induction furnaces,
— equipment for induction heating,
— resistance furnaces,
2. 0. 1 Electroheat installations should be classified as the second class or the third class load. If there is a harmful effect on national economy while several large electroheat installations switch off by accident, they shall be classified as the first class load
Load classification of the auxiliaries of electroheat installations shall decide by harmful effect of faulty switch off.
2.0.2 The distance between transformer, converter and furnace or heater shall be short, but the various parts of electroheat installation shall be easily accessible to facilitate efficient operation, inspection and maintenance.
2.0.3 For electroheat installation, necessary locking devices shall be provided to meet safety of maintenance and correct operative programme.
2.0.4 Devices of protective relay, meter, controller, and conductors shall be installed to facilitate efficient operation, inspection and maintenance, excessive heating, moisture, shock and dust shall be avoided.
2.0. 5 Selection of the cross-section area and arrangement of high-frequency, medium-frequercy current and low-frequency large current conductors shall decrease nonuniform current distribution caused by skin effect and proximity effect.
2.0. 6 Arrangement and material choice of supports, shield plates , pipes, armours and tight elements of conductors, and adjecent metallic parts of the electroheat installations shall decrease the inductive heating effect while higher frequency and larger current.
2.0.7 For electroheat installations, arrangement of the heavy current lines shall be smaller resistance and reactance, and three-phase impedances shall be balanced.