How many  minimum no. of single phase transformers can be used to make a 3 phase transformer?
110115
That can`t be done. You need a three phase one.
981480
A transformer is an electrical device that transfers energy from one circuit to another by magnetic coupling with no moving parts. A transformer comprises two or more coupled windings, or a single tapped winding and, in most cases, a magnetic core to concentrate magnetic flux. A changing current in one winding creates a time-varying magnetic flux in the core, which induces a voltage in the other windings. Michael Faraday built the first transformer, although he used it only to demonstrate the principle of electromagnetic induction and did not foresee the use to which it would eventually be put.\n\nAir Core and Air cooled are different things.\n\nAir Core:\nHigh-frequency transformers may also use air cores. These eliminate the loss due to hysteresis in the core material. Such transformers maintain high coupling efficiency (low stray field loss) by overlapping the primary and secondary windings.\n\nCooling system \nLarge power transformers may be equipped with cooling fans, oil pumps or water-cooled heat exchangers designed to remove the heat caused by copper and iron losses. The power used to operate the cooling system is typically considered part of the losses of the transformer.
961185
You cannot do this directly. Assuming you are talking about a motor, It may be possible to get the motor to turn using a capacitor but you will not get the rated torque (turning force). I'm sure there is plenty 3 phase theory on the internet if you want to see why they are so different\n\nOne way it can be done is by using an inverter that takes single phase input (providing the voltage you require is not higher than the voltage you have or you will then need a transformer as well). The inverter gives you the added value of being able to vary the speed but it may be cheaper to simply buy a single phase motor. As you didn't actually specify the device to be motor, be aware that VSD inverters may not work on other equipment.\n\nYou need to be wary of the size of the device you are trying to operate. Often 3 phase is used for higher powered devices that becomes in-practical to try and run on single phase anyway.
169878
Most AC electrical sources can be converted to other phases, voltages and currents but not to increased power (P = IE) either using semiconductors, transformers or motor generator sets (and transformers).  Usually 240 Volt AC is obtained using two phases of a three-phase distribution system where a single phase is 110 Volts nominal (perhaps 120 Volts actual or stepped up) to double voltage to 240 Volts.  However, in the lab, many different phases, voltages and currents may be required for special applications and suitable converters must be found (or built?).
756481
Normally this is a "Restive" not voltage question/answer, and the proper neutral to ground = 2 Megg ohms (min.) this being incorporated in a residential application.\nHigher voltage in let us say a 3-phase utilization this # is on the low side. (assuming a.c. source. d.c. is a completely different animal!
1083129
1. Motor driven Van de Graaff Generator.\n\n2. High voltage multiplier - Jacob's Ladder.\n\n3. High voltage induction coil - Tesla Coil.\n\n4. Flyback Transformer.
1026240
less than 0.3  for power sations\n0.5ohm for substation\n1 to 2 for homes
1164029
Types of transformers\nIn general, transformers are used for two purposes: signal matching and power supplies.\n\n \n\nPower Transformers\nPower transformers are used to convert from one voltage to another, at significant power levels.\n\n \n\nStep-up transformers\nA "step-up transformer" allows a device that requires a high voltage power supply to operate from a lower voltage source. The transformer takes in the low voltage at a high current and puts out the high voltage at a low current.\n\nExamples:\n\n    * You are a Swiss visiting the U.S.A., and want to operate your 220VAC shaver off of the available 110 VAC.\n    * The CRT display tube of your computer monitor requires thousands of volts, but must run off of 110 VAC from the wall. \n\n \n\nStep-down transformers\nA "step-down transformer" allows a device that requires a low voltage power supply to operate from a higher voltage. The transformer takes in the high voltage at a low current and puts out a low voltage at a high current.\n\nExamples:\n\n    * Your Mailbu-brand landscape lights run on 12VAC, but you plug them into the 110 VAC line.\n    * Your doorbell doesn't need batteries. It runs on 110 VAC, converted to 12VAC. \n\nThis page from the All Electronics catalog (#103, Winter 2003) shows some step-down transformers.\n\nIn many cases, step-down transformers take the form of wall warts.\n\n \n\nIsolation transformers\nAn "isolation transformer" does not raise or lower a voltage; whatever voltage comes in is what goes out. An isolation transformer prevents current from flowing directly from one side to the other. This usually serves as a safety device to prevent electrocution.\n\n \n\nVariable auto-transformers\nA "variable auto-transformer" (variac) can act like a step-up transformer or step-down transformer. It has a big knob on top that allows you to dial in whatever output voltage you want.\n\nThis page from the All Electronics catalog (#103, Winter 2003) shows some variacs.\n\nWARNING: A variable auto-transformer does not provide isolation from line current. For that you need an isolation transformer.\n\n \n\nInverters\nAn "inverter" takes a DC power source and boosts it up to a higher voltage. The most common type of inverter takes power from an automobile and cranks out 110 VAC to run appliances and power tools. Inverters are also used to operate fluorescent lamps from battery power.\n\nTechnically, an inverter isn't a transformer; it contains a transformer (and lots of other stuff).\n\n \n\nSignal Transformers\n"Signal transformers" also take one thing in and transform it to another thing out. But in this case, the power levels are low, and the transformed thing carries some type of information signal.\n\nIn most cases, these transformers are thought of as impedance matching.
947411
Depending on the utility company, some use Dyn11 and others Dyn1 or some other vector group that is universal to their\nsystem.\n\nThe reason being is that  they can be interconnected with the low voltage side of another transformer that is connected to the same high voltage supply circuit.\nDyn 11 means that the vector group is at the 11 o'clock position. If for instance two transformers on the same high voltage line side had different vector groups say Dyn11 and Dyn 1 they would always be 30° out of phase, this would mean that should they be interconnected they would immediately trip the incoming CB/fuses.\n\nSource: Electrical Engineer (ret.) with 45yrs experience
791018
I am pretty sure that there are no rules for minimum numbers of circuits if you mean sockets.  It does not matter how many socket outlets you fit but they must be connected as a ring circuit.  You can have as many sockets on the ring main but the total power drawn from all sockets must not exceed the trip value of you CB or fuse.  Normally it is not recommended to be able to touch your taps and electric sockets and switches at the same time.
482056
I am not sure I understand your question. Are you asking, what are the effects of core losses in relationship with frequency and supply voltage?\n\nThe total power loss in a transformer is a combination of three types of losses. One is due to the DC resistance in the primary and secondary windings. This is called Copper loss. The two other losses are due to Eddy Currents and Hysteresis in the core of the transformer. Copper loss, Eddy Current and Hysteresis loss result in unwanted conversion of electrical energy into heat energy.
958490
There is no conversion that takes place in any size 0 through 7 type S starters. They may be attached to another conversion device but that would be defeating the purpose of the conversion device.  It also may be used to connect a 3 phase generator to its load. \nThese switches are simply a coil energized armature that closes three contacts with incremental current ratings per size through a belcrank arrangement.  Overloads may be integral to the device. Through high speed operation and lack of contact bounce, contact life is extended. The coil can be of a wide range of single phase AC voltages or even a DC voltage.\nThat's the most info I can offer based on what you supplied.
920385
This is not complicated at all.\n\nLM317 is an IC device with only 3 terminals.  Here's an URL to the diagram:\n\nhttp://www.national.com/pf/LM/LM317.html\n\nYou willneed a transformer, full bridge rectification circuit, and filters.   You need to spec the transformer so that the output of the rectifier/filter is at 15V DC at full load.  Notice that under no load, the ouput will be at sqrt(2) * (ac voltage).  Under full load, it should drop to the RMS value of the outout.  (basically means to use the 15V transformer)\n\nThe filter capacitor must be large enough so that ripple will be at minimum at the full load.  4700microF or larger should be sufficient.\n\nRemember to heat-sink the 317, as it will get quite warm at full load.
222925
Dig here:\nhttp://www.scientifics.com/transformers.htm
362491
A transformer style welding machine converts the high voltage and low current electricity from the utility into a high current and low voltage, typically between 17 to 45 volts and 190 to 590 amps. This type of machine typically allows the welder to select the output current by either moving the core of the transformer in and out of the magnetic field or by allowing the welder to select from a set of taps on the transformer. These machines are typically the least expensive to purchase for hobbyist use.
3409
Single phase usually refers to AC power. The voltage and current in AC power alternates, and when plotted it will look similar to a sine wave.  Commercial AC power is generated and  transmitted in three phases, 120 degrees apart.  So single phase is one of those phases.  Homes almost always have only one phase, comercial locations can have three phases.
834597
No \nThere are no optimal frequencies for a transformer.