Requirements for working conditions of induction melting furnace
Power supply
Strengage Station: llOkV/lOkV
Three-phase alternating current: 380 V to 10 and 50 Hz to 2.
single phase alternating current: 220V to 10V to 50 Hz to 2.
compressed air: 0.5 MPa~0. 70 MPa.
Industrial water: municipal tap water.
Working hours: two shifts, 250 days per year
1、Technical requirements for intermediate frequency induction melting furnace
melting hot metal technical parameters and requirements
Hot metal grade: molten iron is mainly cast iron of HT250,HT300 and other grades.
the control precision of the main chemical composition of hot metal is C ±0. Si ±0. CE + 0.10; and add appropriate amount of Cu,Cr and other alloy elements.
the intermediate frequency power supply of the melting furnace adopts "one towing one" single power supply type, that is, one power source of each set of electric furnace and one furnace connect to melt the solid iron material.
molten iron capacity: the actual melting of qualified iron per hour of electric furnace is more than 2T (excl. the auxiliary time of feeding, hot metal composition inspection, tempering etc.).
the furnace must melt and heat the 2T cast iron coolant in the furnace to 15000C within 60 minutes, and the power of the power supply shall be determined by the supplier himself.
molten iron temperature: ≥ 1500 C.
melting power consumption: the temperature of molten iron is 1500 C, the average power consumption per ton of molten iron is less than 650 KW ·h.
ensure adequate electromagnetic stirring force for molten pool metals.
noise level: measured on the operating platform, 1 m from the stove, less than 85 db. after background noise.
equipment configuration and technical requirements
The melting furnace consists of medium frequency power supply, furnace body, hydraulic device, cooling water system, emergency water system, low-voltage control cabinet and so on. Equipment configuration and supply range
if power supply
The rated power of intermediate frequency power supply is determined by the supplier, and the transformer capacity is determined by the supplier in the design of the single power supply of "one towing one". If power supply must be produced by well-known manufacturer, the SCR and capacitor in power supply must adopt well-known brand, control circuit and other main electrical components, such as reactor, transformer, trigger module, etc., should be stable and reliable. Cooling water hose must be carbon-free hose, power supply terminal must be equipped with automatic air circuit breaker. The power supply adopts 12 pulse rectifier. Power cabinet and control cabinet must have complete instrument and operation interface.
the power factor of the system is not less than 0. 95.
if power conversion efficiency: not less than 97. 5%
frequency conversion power supply must have frequency automatic tracking function, so that the power supply and furnace always keep the best match. The operator does not need to switch the connection of the capacitor so as to avoid the operational factors affecting the efficiency of the system.
the high order harmonics produced should meet the requirements of standard JB/T14549-93 power quality and public power grid harmonics.
the design of electrical components is reasonable, the discharge is neat, the maintenance and replacement of parts is convenient and quick, and all the major heating elements are equipped with reasonable cooling methods according to the need.
the success rate of if power supply must reach 100.
the power supply cooling water input with water pressure relay, control when there is no cooling water, do not start or cut off the intermediate frequency power supply.
in order to ensure the safety, stability and reliability of the if power supply in use, the following protection functions must be provided:
1、main circuit short circuit protection
2、thyristor overvoltage protection
3、main circuit misphase protection
4、cooling water temperature protection
5、main circuit phase gap protection
6、cooling water pressure protection
7、thyristor overcurrent protection
8、leakage furnace protection
if power cabinet
if power supply cabinet door is interlocked with power cut line, the main power supply is cut off when the electric cabinet door is opened, and the lighting working lamp and single-phase AC220V three-hole standard power outlet are installed in the control cabinet for inspection and maintenance.
reasonable heat dissipation devices should be provided in the cabinet to ensure the clean and low temperature of the cabinet and avoid the pollution of unclean air.
the cabinet door is enclosed with a seal and each door is fitted with a secret lock.
the control cabinet should adapt to the working environment and have waterproof and dustproof structure. The sealing on the door should be oil-resistant and the protection grade should be IP55.
the control cabinet is equipped with red, yellow and green display alarm light.
equipment nameplate shall be affixed to the door of the control cabinet, indicating the manufacturer of the equipment, the date of departure, the serial number and specifications, model, input voltage, power, weight of the equipment, etc.
the cable must be classified and numbered as required, indicating the category, transfer box number, terminal arrangement number; all control lines, power lines shall be threaded through the pipe, and the pressure terminal head shall be arranged on the terminal line.
device identification in cabinet
all electrical components of the control cabinet shall be marked with Chinese instructions and numbers above them, and oak shall not be on the component body.
the text code of the logo should be consistent with the drawing.
the mark handwriting is clear and not easy to fall off.
each terminal and terminal row shall be marked and in accordance with the drawings.
Non-toxic dielectric shall be used in capacitors.
capacitors should be selected with large capacity, low dielectric loss, small volume, less heat, safety and reliability.
Intermediate frequency power control cabinet
The control cabinet is made of steel cabinet, which consists of control instrument, power control turntable, button switch and power indicator lamp.
The control cabinet should ensure the convenience of operation and maintenance inspection.
The primary voltage of rectifier transformer is 10kV, and the rated capacity is determined by the supplier himself.
A manual voltage regulator is installed on the high voltage side of the transformer. Adjust the output voltage in 5%, 2. 5% and 5%
