To Optimize and Generate Effective Design of Distribution transformer up to 80MVA / 220 kV by giving a few inputs. TDPro is used to automate Transformer design process by entering the basic design inputs. TDPro automatically computes electrical & mechanical calculations, Bill of quantity & costing. TDPro outputs Winding card, Core card, Design data sheet, Raw Material Cost sheet & General Arrangement Diagram. It complies with all types of reference standard and is useful to design oil cooled distribution transformers of rating up to 80MVA / 220kV class.It also gives designs of dry type transformers upto 2.5 MVA/36 kV.
ProteCT™ current transformers eliminate the need for a shorting block and produce only a very low voltage when they are in an open secondary condition, a safety feature inherent in the product design. Current transformers (CT) are used in High Voltage (HV) and Medium Voltage (MV) installations to give an image of electrical current to protection relays and units and metering equipment and they are designed to provide a current in its secondary proportional to the current flowing in its primary.
In TDPro software, different types of phases, ratings, windings, core with all possible variation are standardized. The bill of material will have all component details like quantity, weight, values of variable parameters, material code, material specification, & Remark etc.
TDPro Supports
Transformer Types | Distribution, Power, Isolation, Ultra Isolation, Lighting. |
Reference Standards | IS 2026, IS 1180, IS 11171, IEC 60076, ANSI, CBIP, ECBC, SABS, EU-ECO and GOST. |
Ratting | 5KVA to 10000 KVA with 2 windings, 3 phases, up to 36 KV class & upto 80MVA / 220kV with 3 windings. |
Cooling Types | Dry type (VPI) and Oil cooled |
Core Materials | CRGO and AMORPHOUS |
Core Construction | Wound Shell Type, Wound Core Type, Rectangular Type, Amorphous Shell Type, Amorphous Core Type, Circular / Circular Stacked Core and Flat/Flat Stacked Core. |
Winding Materials | Copper, Aluminium and Copper-Clad Aluminium. |
Winding Types | CO-CO, Layer-Layer, Layer - CO, Foil - Layer, Foil - CO, Foil - Disc, Layer - Disc, Disc - Disc |
The software will be used to take the input from the user, software will do
• LV & HV winding details with Ratio error calculation • Core details • Insulation details • Tank, Radiator & Conservator details • Fitting & Accessories details • Short circuit calculation details • Bill of material • General Arrangement Drawing • Rating Plate Drawing • Terminal Marking Plate Drawing | Approval Documents: • GTP, • Core Area Calculation, • Flux Density Calculation, • No Load Cruel, • Load Loss Calculation, • Fins Calculation, • Thermal Ability Calculation, • Hot Spot Temperature Calculation, • Current Density Calculation, • Oil Absorption Calculation, • Symetrical Short Circuit Calculation |
Manufacturing specifications: • LV & HV winding specifications • HV Coil Assembly • Core Coil Assembly • Internal Drawing • Winding Arrangement | |
Manufacturing Drawings (2D & 3D): • Part Frame • Tank with fitting and Accessories • Loose Part Drawing |
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YOU ARE HERE: HOME >BASICS > WIDE BAND RF TRANSFORMERS
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What are wide band rf transformers?
Wideband rf transformers are simply transfomers designed to provide an impedance transformation over a broad frequency range. In amateur radio applications we wind these transformers on ferrite toroids. A common impedance transformation is 200 ohms to 50 ohms using a bi-filar winding. Here is an example from our broad band amplifiers tutorial.
Figure 1. - wideband rf amplifier with shunt feedback and emitter degeneration
Transformer T1 is a broadband rf transformer.
Designing wide band rf transformers
In the design of these kinds of wide band rf transformers the primary reactance is usually around 5 times the primary impedance. With a 200 ohms to 50 ohm transformer, we would allow a reactance of 1,000 ohms at the lowest frequency of interest. Just as an example consider we were building a broad band amplifier for the amateur bands and going down as low as 1.8 Mhz.
For this example we would need bi-filar windings which have a reactance of 1,000 ohms at 1.8 Mhz, this means a required inductance of around 88 uH. A look through the Amidon data book tells me that ferrite toroid FT-50-61 as one example can provide me with an AL factor of 68mH / 1000 turns.
This means if 1,000 turns were wound on the toroid it would give us 68 mH. Yes that IS milli-henries, these are ferrite toroids.
Calculating turns for wide band rf transformers
To wind a wide band rf transformer with an inductance of 88 uH (yes that's micro-henries) which is in fact 0.088 mh we use the following formula:
Turns = 1,000 X SQRT (L in mH / AL factor) = 1,000 X SQRT (0.088 / 68) = 36 turns.
Our wide band rf transformer needs 36 turns to achieve an inductance of 88 uH.
Winding the wide band rf transformer
Because this is a bi-filar winding for our wide band rf transformer, we need two lengths of wire which we will 'twist' together at a 'pitch' of 2.5 turns per inch or 1 turn per 10 mm. If you anchor one end of the two wires together in a bench vise and fix the other ends securely in a hand drill (a bent nail or fish hook helps here) you then gently 'stretch' the wires first. Then you slowly turn the hand drill and notice the two wires 'twisting' together, as you proceed you will notice more and more twists appearing. Stop when you have about 2.5 twists to the inch. Stretch the wires once more.
Wind 36 turns through the toroid and that is it! To use in an application such as figure 1 above you need to pay attention to the 'phasing'. Notice the two dots on T1 above? They indicate the start of each wire. Use an ohmmeter to find the start and finish of one winding, mark it in some convenient manner e.g. coloured pen. The other winding should then be obvious.
Commercially manufactured wide band rf transformers
Coilcraft is one manufacturer of wide band transformers which provide reliable performance.
The transformers are offered in tapped or untapped configurations and are packaged in a low-profile DIP-style plastic case. All parts are available in either a surface mount version or a through-hole version that’s compatible with standard DIP sockets.
![Current Transformer Design Software Current Transformer Design Software](/uploads/1/1/9/4/119499609/367801585.jpg)
Applications include impedance matching, voltage or current transformation, DC isolation, balanced / unbalanced mixing, matching, power splitting, coupling, and signal inversion.Custom wide band transformers with special combinations of impedance ratio, insertion loss, frequency response, and current handling are also available.
Designing wide band rf transformers for different impedances
Alright what if you need something other than a 200 ohm to 50 ohms transformer, how would you go about it?
What I tell you here now is applicable from DC to daylight. What that means is, it is equally applicable to an audio transformer with a bandwidth of 100 Hz to 3,000 Hz (for an audio transformer) as it is to a broadband transformer designed to operate at say 7.00 to 7.50 Mhz. Read on.
Firstly you need to pick either a lower 1 dB or 3 dB bandwidth. Wozzat??? Look at figure 2 below where I present my usual scungy drawing - I'm no good at this graphic arts caper, not the program, just my lack of artistic talent.
Figure 2. Download arcgis crack. - band pass filter characteristics
Here I've crudely depicted a range of frequencies being passed by a filter and indicated the 1 dB and 3 db points. A 1 db point is where the power output is about 80% of the band pass power or 90% of the voltage level. A 3 db point is where the power output is about 50% of the band pass power or 70.7% of the voltage level. If you can't understand decibels then you need to look at the decibel page
In your broad band transformer you need to determine the lowest point you can tolerate in frequency. Entirely for discussion purposes I've selected 5 Mhz for both 1 dB and 3 dB to demonstrate the formulas. Also I'm going to construct a broad band tranformer to operate between 14.4 ohms and 50 ohms.
For the 1 db point to be 5 Mhz, I use the formula Lp = R / ( 2 X Pi X Fo) and for the 3 dB point, I use the formula Lp = R / ( 4 X Pi X Fo). The general formula for any other dB level is a bit difficult to reproduce here but contact me and I'll give it to anyone who wants it.
The first formula simply gives you an inductance equal the reactance of R or in our case we're using 14.4 ohms at 5 Mhz. This results in an inductance of 0.458 uH. The second formula simply produces half that inductance or, 0.229 uH.
Back to the result of 0.458 uH, that could easily be achieved with 10 turns on a T-50-2 toroid. Alright we have a T50-2 toroid with 10 turns on it, this is supposed to represent 14.4 ohms at 5 Mhz. To match to 50 ohms all we have to do is work out the turns ratio. Impedance transforms as 'the square of the ratio of turns'. Then 50 / 14.4 = 3.472' and the square root of this is 1.86 so we need on the secondary 1.86 times more turns or in our case 19 turns.
IF our output were terminated in a genuine 50 ohm load then the square of [19 /10] being the turns ratio would be reflected back giving (if you work it out) a source of 13.85 ohms.
The CRITICAL aspects here are: a) turns ratio AND; b) final termination being a genuine 50 ohm load.
What is the upper frequency limit of our wide band rf transformer?
The high frequency limit is influenced by the leakage inductance Lk and distributed capacitance of the inductor forming a second order low pass filter and is influenced by a very wide range of factors. The higher the inductance, then the lower or flatter the low-frequency end but, this comes at a price of higher Lk and distributed capacitance limiting high frequency response. Often a compromise is needed for high ratios of frequencies. Although I have never tested it, I would imagine at least one octave bandwidth could easily be accomodated e.g. 2.5 Mhz to 5 Mhz or 5 Mhz to 10 Mhz.
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RELATED TOPICS ON WIDE BAND RF TRANSFORMERS
![Transformer design calculator Transformer design calculator](/uploads/1/1/9/4/119499609/927429039.jpg)
broad band amplifiers
tuned circuit amplifiers
impedance
inductance
reactance
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the author Ian C. Purdie, VK2TIP of www.electronics-tutorials.com asserts the moral right tobe identified as the author of this web site and all contents herein. Copyright © 2000 = 2001, all rights reserved. See copying and links.These electronic tutorials are provided for individual private use and the author assumes no liability whatsoever for the application, use, misuse, of any of these projects or electronics tutorials that may result in the direct or indirect damage or loss that comes from these projects or tutorials. All materials are provided for free private and public use.
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Updated 27th February, 2001