A Training seminar on Induction Furnace by

A Training seminar on Induction Furnace by Stead Fast Engineers Pvt. Ltd.http://www.steadfastengg.com/COMPANY PROFILEEstablished in 1990, Stead Fast Engineers Pvt Ltd is an engineering company engaged in designing and manufacturing of Induction Melting furnaces, Induction Billet Heaters and Refractory Lining Machines for Foundries, Steel Plants and Forging units. With the help of years of experience and a highly skilled team, we create products with attention to every minute detail thereby making the products both user friendly and economical.Stead Fast Engineers provides world class induction heating and melting solutions for both ferrous and Non ferrous with a great focus on customization so that every machine is nothing less than perfect. With a family of more than 400 satisfied customers all over the country and abroad, Stead Fast Engineers is expanding at a rapid pace. With offices located in major cities we ensure that the service is quick and effective and breakdown time is negligible. Adopting stringent quality management systems during different stages of production - the pre-process, In-process and pre-dispatch stage we believe in manufacturing the best quality every time.

INDUCTION HEATING/MELTINGIf an AC current is fed through a coil, the electromagnetic field that is produced is constantly changing. This changing magnetic field induces electrical current (AC) in another circuit that is held close .This induced secondary current can be utilized to generate heat in the circuit of the second conductor by exploring the electrical losses due to the current. These losses are due to Hysterises and Eddy current.

BLOCK DIAGRAM

Input current &voltageDCChokeLoad(Resistor)Inverter controlConvertercontrolConvert PulseInvertPulsePANELSL Card, ITC Card, Burden Card, Relay Card3 SupplyET- INDUCTION MELTING FURNACEET-Induction Melting Furnace constitute following part:Generator Panel DC ChokeCoil Cradle AssemblyDe-Mineralise Water Circulation UnitChangeover SwitchHydraulic Unit

GENERATOR PANELGenerator Panel consist of following section:3-phase Bridge Rectifier with freewheel diode.(DC to AC) Inverter sectionStarting CircuitControl Electronic PCB Cards sectionTransformer for power supply

Incoming mains 3- supply from furnace transformer is rectified by Full Control Bridge Rectifier.Six identical Thyristor which are connected in Bridge configuration to convert Incoming AC to Corresponding DC. Six Thyristor stand for R+, R-, Y+, Y-, B+ & B-.

3-phase Bridge Rectifier with freewheel diode(DC to AC) Inverter sectionThe inverter is responsible for converting High Voltage DC to AC to feed it to the load circuit . It is a single phase bridge Parallel InverterThyristor are connected in four arms. Each arm has serially stack thyristor in range of 3-4 depending of output Voltage designed. Thyristor in diagonal pair are fired in each half cycle of medium frequency , this frequency is determine by parallel resonant LC circuit.

Starting CircuitStarting circuit plays major role for reliable starting of furnace.It consist of Starting Card, Start Capacitor, Start Choke, Start Thyristor Module and Start Contactor unit.

ELECTRONIC CONTROL CARDThis section consist of following PCB cards:ET-SL ( Sequence and Limit Control Card )ET-ITC ( Inverter Control Card )ET-TOV ( TOT Generation and Over voltage Detection)ET-PS (Power Supply)ET-SC ( Starting Card)ET-133/2 ( Converter Firing Pulse Generation Card)ET-133/3 (Amplification and Isolation Card)ET-77 ( Inverter Firing Amplification and Isolation) ET-84 ( Water Conductivity Measure ) ET-125 ( Earth Leakage Detection)ET-BRDN ( Burden Board)ET-RLY ( Relay )

ET-SL

ET-ITCWorks on the principle of transformer, I.e primary and secondary are linked by magnetic flux. Transformer is a electro-magnetic device so here in DC , Choke acts only as resistance , which is in microohms.DC chock converting pulsating DC to pure DCIt prevent thyrister of inverter from large current

DC CHOKECOIL CRADLE ASSEMBLY

FURNACE COIL

It is made of high conductivityFor maximum efficiency of coil a space is maintain by the spacer.Additional stainless steel cooling turn at the top and bottom is clamped for providing uniform cooling through out of the coil cradel.DEMINERALISE WATER CIRCULATION UNIT

DM water is deminrlised water.DM water has very less conductivity (less then 10/semens.DM water is widely used for cooling purpose of power equipments.As for example in the coil cradel, change over switch etcCHANGE OVER SWITCHThis is offload switch used to alternately connect two furnace crucible with single power source. It can be operated manually or pneumatically. It is water cooled to allow better heat dissipation.The contacts points of switch is made by silver for better contacts.The current carrying capacity is from 2KA to 20KA.

HYDRAULIC UNIT

This is the tilting structure of furnaceWith the help of hydrolic unit we can tilt the furnace upto 95Tilting process is done with the help of oil pressure which is created by motorThe oil use for tilting is enklo-54 which has high viscous in nature