| Ques : | Why do you call your furnace system VIP POWER TRAK ? | |||||||||||||||
| Ans : |
INDUCTOTHERM introduced the first all solid state high / medium frequency induction Power supply in 1968. We call it 'VIP' short form of Variable Induction Power. What Variable Induction Power means is that, it is possible to vary or change the power delivered to the metal. Until 1968 when Inductotherm first introduced Solid State Inverters with SCR's (Thyristor) for Induction Melting application, it was not possible to adjust the power to whatever level the operator wanted to. Subsequent to the VIP development, Inductotherm came out with the idea of Power Trak in 1976. As its name suggests, VIP POWER TRAK has the unique ability to automatically "track" the changing impedance of a coreless induction furnace in order to produce maximum rated power under virtually all furnace loading condition. Thus VIP POWER TRAK is the only furnace in the market that has the ability to deliver full power from start to finish. | |||||||||||||||
| Ques : | What do you mean by VIP POWER TRAK - R ? | |||||||||||||||
| Ans : | Inductotherm's new generation of VIP power Trak R systems includes the most rugged and technologically advanced induction power and control units ever built. This system is engineered to Inductotherm's exacting standards. Full Power,Full Control Continuously. During melting operations,the VIP Power Trak automatically provides full power throughout the meltcycle.No molten heel is required and there is no need to switch capacitors or voltage taps.Efficiency starts high and stays high,delivering 97.5 percent power conversion efficiency to produce more molten metal per kilowatt than competing systems. Inductotherm's melt rates are guaranteed. From the system's rugged and highly responsive Z-Control Board to its heavy copper bus bars, Inductotherm's VIP unit incorporates an impressive array of advanced features. | |||||||||||||||
| Ques : | What is a DUAL TRAK? | |||||||||||||||
| Ans : | DUAL-TRAK system consist of one VIP DUAL-TRAK with two equal capacity furnaces.In a medium Frequency batch type melting furnace metal of finite quantity is charged regularly,when the charge has been melted and superheated to the desired pouring temperature,the furnace has completed its melting duties and the molten metal is available to use. At this point,the power to the furnace is either turned off or reduced in order to maintain the temperature of the molten metal during pouring.Thus,a full melting cycle consist of the time to melt and superheat the charge plus the subsequent period of lost time for removal of slag,checking the temperature,chemical analysis (and adjustment, if required) of the melt tapping the furnace and putting in the next charge. The production capability of furnace is more or less directly related to the ratio of melting time to the over all cycle time.If the lost time can be kept to a minimum,the effective utilization of the equipment will be high and the actual production rate obtained will approach to the designed melting rate of the furnace.Normally in iron foundries foundrymen get utilisation of the melting power from 55 to 75% with normal power trak system depending on the loss time.By using the Dual-Trak System,this utilisation can be increased up to 90 to 95% or even to 100% if operating ideally. Another advantage of Dual-Trak system is whenever you want more quantum of metal at time to pour for bigger casting,you can use this system successfully by holding in one crucible and melting in second crucible so that twice the amount of metal at one time is available for pouring. | |||||||||||||||
|
| ||||||||||||||||
| Ques : | What are the metals that we can melt in Induction Furnace. | |||||||||||||||
| Ans : | You can melt almost anything that conducts electricity in Induction Melting Furnace. For example Gold, Silver, Stainless Steel, Iron, Copper, Aluminium, Zinc, Tin etc.. However it is not usually economical to melt low melting metals like zink or lead or the tin in this high investment Induction Furnace. | |||||||||||||||
| Ques : | Can we run your Induction furnace on D.G. Set? | |||||||||||||||
| Ans : | Yes, Inductotherm design is such that it can accept power from Generator easily. However please note that 20 % to 25 % Higher rating of DG Set is recommended when operating at full load. | |||||||||||||||
| Ques : | How can I tell what size of induction furnace (kW / Hz / Kg) is most suited to my application technically and commercially ? | |||||||||||||||
| Ans : |
This is the most common problem bothering most buyers. Let us go over the selection process systematically and step wise : VIP TYPICAL MELTING RAGTES (KG/HR)* Step 1 : What metal or alloy do you want to melt most of time ? What is your desired pouring temperature? Melt rates for different metals are different. As well as superheating beyond the melting temperature will also mean more time so different melt rate (kg / hr) Step 2 : Once we know answer to step - 1, you must tell us your requirement of liquid metal in tons per day or tons per months. Also number of working hours per day. A. THE STEEL INGOTS : Suppose you want to melt 1400 Tons / month of mild steel ingot at 16000C. Considering 25 working days, it would mean 1400 Tons / 25 days = 56 Tons / day of liquid metal. Suppose you want to work 3 shifts. Thus, your pouring requirement is 56 Tons / 24 hours = 2.33 Tons / hour @ 16000C. But you can not run the furnace 100% of the time, as you would require time for deslagging, recharging etc. Thus utilisation of furnace is less than 100%. For ingot manufacturer, often this utilisation factor is above 90%. But considering relining and sintering time etc. we can say on the average 80% - 85% utilisation factor. Thus, melt rate of the furnace should be 2.33 Tons per hour 10.8=2.9 Tons/hour @ 16000C. If you now look up the enclosed table you will find that 1500 kW is the nearest size furnace for your requirements of 1400 Tons / month, and you should have at least 1690 KVA power exclusively for the furnace. THE CASTING: (i) Suppose, you want to produce 500 Tons finished steel casting and suppose that your casting yield is 65% and your utilisation is only 70%. Considering working for 25days you require 20 tons of finished castings per day. But your molten metal requirement will be 20 Tons / 0.65 = 30.77 tons / day. Pouring Rate = 1.28 tons per hr / 0.7 = 1.83 tons / hour @ 15500C. If you refer to the table then the nearest size furnace will be a 1000 kW, in this example. (ii) For better utilisation of furnace please ask more details on DUAL TRAK Step 3 : From the above we have determined only your total kW requirements. Now let us see whether you need only one 1000 kW furnace system or say two 500 kW furnace systems ? This actually depends on the KG weight of molten metal required per batch or heat. The batch quantity depends on weight of largest and smallest castings, material handling facility etc. If you need 1.5, 2 or 2.5 Tons metal at a time then, 1000 kW is okey and would cost you less compared to buying two 500 kW systems. But suppose you want only 300 KGs or maximum 500 KGs at a time you must consider buying two 500 KW / 1000 Hz VIP POWER TRAK with 300 KGs or 500 KGs furnaces (Crucibles). Step 4 : Now that we have decided total kW of the frequencies and Kg holding capacity of the furnace, we should select the right frequencies. Unfortunately, section of frequencies is usually not available. As suppliers restrict any particular kW to utmost one ot two different frequencies to keep their inventory of parts within manageable level. Usually this is not a big constraint as it appears because there are many combination of kW and KGs available at different frequencies. Please see the table of range. Also, remember that frequency is only of the factor affecting stirring. It is possible to have mains frequency furnace and still no stirring at all if kW are low and holding capacity (tons) very high. | |||||||||||||||
|
| ||||||||||||||||
| Ques : | Do you mean to say that you really cannot compare prices of two different suppliers even if they have quoted for the same holding capacity of the crucible say 3 ton or 5 ton,etc. ? | |||||||||||||||
| Ans : | Yes, You are right . You will end up with wrong comparisons that way . It is as ridiculous as asking for a quotation for different types of cars like Car A or Car B by the holding capacity of their petrol tanks. What is of primary importance to you - Kilometres per litre rating or litres holding capacity of petrol tank ? May be a more efficient car with only 15 litres holding capacity petrol tank could take you 300 kilometers non - stop while a petrol guzzler may have 25 litres tank but it will take you only 250 kilometers non - stop. Now it will be wrong comparison to say that the car with 15 litres holding capacity of petrol tank should not more than 60% of 25 litres holding capacity car. Wont't it ? The correct way of comparison is kilometer / litre under the same road condition for both the cars. That way smaller car will give you 300/15=20 Kilometres per litre compared to gas guzzler car with 250/25=10 Kilometres per litre is obvious. Beside, you can see from attached table of range, there are at least 3 to 4 different sizes of kW for any particular holding capacity of the crucible . For example, we can supply a 3 Ton furnace with 1000 kW, 1250 kW, 1500 kW,1750 kW, 2000 kW 2250 kW or even 2500 kW. Which one should we quote ? Actually, you are interested in maximum tons / hour (production rate) for the KVA power sanctioned to you and not just in tons of holding capacity. | |||||||||||||||
| Ques : | Does this mean that instead of asking quotation in terms tons crucible capacity, we should ask by its kW rating? | |||||||||||||||
| Ans : | Wrong again ! For over 50 years since the first Induction Melting unit was successfully operated, traditional ratings have been expressed in kilowatts, regardless of how much metal they are capable of melting. If the foundryman has to determine for himself where kilowatts are measured, he has to be able to understand the intricacies of electronic circuitry. The rating may be taken at any of the following points in the circuit : * Input Power from the line * Transformer output * Inverter output * Unit output to the furnace Or you may use nominal power and maximum power - or both. All of these readings will differ and the result is confusion of the buyer and user. How should induction melting equipment be rated ? On the basis of melting capability or kilowatts of power delivered ? As a foundryman, what are you concerned with - production or electrical rating ? The answer is PRODUCTION, of course ! Naturally, the electrical energy required to operate your equipment is important to you. But to rate an induction system by kilowatts is a little like buying an automatic machine based on rated air consumption instead of moulds per hour production capability. In other words, production is what you should be buying - not energy input. Once again, we can quote 3 or 4 different sizes (tons) crucibles for each given kW as is apparent from the enclosed Table. Which one should we quote ? Thus you can see that the furnace system has to be designed custom made depending on each individual needs. But remember that only input KVA and "THERMAL EFFICIENCY" of the frequencies decides your daily production. Frequency or holding capacity of crucible has nothing to do with melt rates. Frequency is merely one of the factors affecting stirring action. Holding capacity (tons) is decided by your casting size. It will also decide whether you need only one larger kW furnace system. | |||||||||||||||
| Ques : | What is this THERMAL EFFICIENCY ? | |||||||||||||||
| Ans : | THERMAL EFFICIENCY means ratio of amount of energy actually given to the charge compared to amount of energy spent per ton (KWH/ ton) of weight of charge. THERMAL EFFICIENCY will not only take into account the losses in the electrical system (3 to 10%) losses in the connecting bus bars, water cooled leads as well as as induction coil (18 to 22%), losses in keeping the lining hot (4 to 6%), losses in radiation (2 to 4%) etc. Thus a thermal efficiency could be any where from 55% to 75% depending on the size of the furnace and the design ingenuity of the furnace supplier. As a purchaser you are concerned with the total THERMAL EFFICIENCY and not ELECTRICAL EFFICIENCY, the furnace system which puts in most energy into the charge by requiring least input KVA or input kW must be your choice. After all, the efficiency of any equipment is the ability of the equipment to achieve its function with minimum loss or waste. For equipments like induction furnace, it should be how much energy it gives to the metal from whatever it take from the supply line. The installed KVA indicates what it takes and melt rate indicates what it gives, and the performance index indication of benefit for a given expense. If we continue our example of car, the litres of petrol is what car take and distance in kilometers is that it gives and the performance index is kilometers per litre. But no furnace manufacturer specifies thermal efficiency in his technical literature. So how do you judge which frequency is better ? The best way for you to compare two system is by their performance index. | |||||||||||||||
| Ques : | Please explain in more detail what is this Performance Index in relation to Induction Furnace ? | |||||||||||||||
| Ans : |
Performance Index = Kg /Hour (at a particular pouring temperature)KVA. Unfortunately, all the furnace suppliers quote their melt rates at different temperatures. Some quote them at 15000C or 15500C while others quote at 16000C. Inductotherm usually quotes them at 16500C. Steel at 15500 C contains approximately 356 KWH/ton of heat energy while steel at 16500C contains approximately 389 KWH / ton.Naturally, melt rate at lower temperature would look much faster. So if your pouring temperature is 16500C then you should discount all melt rates at 15500C by at least 8% to convert them to equivalent melt rated at 16500C. Although the radiation losses at such high temperature are not linearly proportional one can approximately convert melt rates at different temperature to those equivalent at 16500C by using the multiplier given below : Multiplier for equivalent
For example, if the melt rate quoted is 3 tons / hour at 15500C it would approximately mean 3 tons x 0.92 = 2.76 tons / hours at 16500C. Similarly, melt rate of 3 Tons / hour specified at 16000C would approximately mean 3 Ton x 0.95 = 2.85 tons / hour at 16500C Please remember performance index is the only true measure of comparisons of efficiency because production rate is the real output on which you are going to make money while KVA consumption is where you are going to pay your electrical bills. For example, to achieve 38 tons to 40 tons of molten steel a day all you need is Inductotherm's 1000 kW (1150 KVA) new Line isolated VIP Power Trak - R attached to anything from 1.5 Ton, 2 Ton or 2.5 Tons. While some competitive designs are so inefficient that they need nearly 1250 kW to 1400 kW (about 1800 KVA) at average 32 tons per day production. More KVA installed means you will have to incur additional expense in terms of Security deposit and contact demand charge while getting sanction for KVAs from electricity Board. In additional to this the recurring cost of maximum demand charge / KVA installed will be additional expenses per ton of metal produced. | |||||||||||||||
| Ques : | What are the pit falls to avoid while comparing performance index of two systems ? | |||||||||||||||
| Ans : | (1) It is amazing how often some customer assume that specification of say 5000 Kg melting to 15500C in 64 minutes as a melt rate 5 tons/ hour. Well Sir, 4 minutes every hour means almost 90 minutes in a day. Correct way is to divide 5000 Kg by 64 minutes and then multiply by 60 minutes to arrive at 4687.50 Kg / hour @ 15500C. To convert it to 16500C means a further discounting by 7%. It gives us only 4359 Kg/hour @ 16500
C. But in the process it requires KVA installation of nearly 3280 KVA. Well, Inductotherm could supply a furnace system which will produce a minimum of 5220 Kg/hour @ 16500C given the same 3280 KVA. A difference of 5220 - 4359 = 861 Kg/hour every hour or a huge difference of say 15 or 16 ton/day and difference of whopping 4500 to 5000 tons/year every year. That's a lot of production to be lost on misinterpretation of technical data given by different suppliers. (2) Also some manufacturers get away by pitting a foot - note that their melt rates and power consumption are guaranteed under specified conditions with tolerance ±10%. In today's competitive market such huge tolerance can make or break an enterpreneur who is ambitiously embarking on crores of rupees of investment. So, it is time that every Indian metal producing entrepreneur start comparing Apple with Apple and ask right questions to induction furnace suppliers competing for his valued order. | |||||||||||||||
| Ques : | Well there must be a catch here. If full power from start to finish would result into fastest melt rate then it must be consuming lot more energy per ton, right ? | |||||||||||||||
| Ans : | Wrong ! Often people believe that faster melt rate means more power consumption or energy consumption / ton. kWh / Ton = Input kW / Tons per hour = (Output KW / Electrical Efficiency) / Tons / hour The person who melts in shortest possible time with same KVA rated furnace would have maximum ton/hour as production rate and so he will consume that much less units per ton as is obvious by above formula. Besides our furnace will not take full power unless you have some charge in the crucible. It will automatically settle for lower power and give your melter indication that the furnace is hungry. So no waste of power there. | |||||||||||||||
| Ques : | Can we attach computer with your VIP units ? If yes, tell us more about about this ? | |||||||||||||||
| Ans : | Yes, You can attach the computer with our VIP Power Trak - R. We call it Melt Manager. With its on board computing power Melt Manager is able to perform a full range of diagnostic checks on itself and the furnace each time your system is started. These testes are designed to detect problems before full power is applied to protect your equipment from damage, and Melt Manager continues to check the operation of the system throughout the full melting cycles. Melt Manager has been engineered for easy retrofit to existing Inductotherm power supplies. So you can add the advantages of melt Manager's diagnostic and Automation capabilities to your present VIP PowerTrak. |
| Last update on - 7th March, 2007 |