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WHAT TYPE OF transformers has secondary current of the same order as the magnetising current?
Wiki User
∙ 12y ago
A one to one, i.e. isolation, transformer.
CommentIt might be worth pointing out that the secondary current is determined by the load, and the primary current is then determined by the secondary current. The questioner appears to think that the secondary current is determined by the primary current.
Wiki User
∙ 12y ago
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Why current transformers secondary is always short circuited?
Unless a burden (i.e. meters, relays, etc.) is connected to the CT, current transformers should always be shorted across the secondary terminals. The reason is very high voltages will be induced at the terminals. Think of the CT as a transformer, with a 1 turn primary and many turns on the secondary. When current is flowing through the primary, the resulting voltage induced in the secondary can be quite high, on the order of kilovolts. When a CT fails under open circuit conditions, the cause of failure is insulation breakdown, either at the shorting terminal strip, or at the feedthrough (in the case of oil filled apparatus), because the distances between terminals are not sufficient for the voltages present.
What is rectifier welding machine?
A welding rectifier takes in the a/c output of a welding transformer, and the output is d/c. Used with old school welding transformers which were all a/c, in order to get d/c for use with low hydrogen rods etc.
What happen when the polarity of transformer reversed?
You cannot 'reverse' the polarity of a transformer -it is either wound with 'additive polarity' or 'subtractive polarity', and there's not much you can do about it! For a single transformer, its polarity doesn't really matter. But if you are going to parallel two transformers, then you must know the polarity of each transformer in order to avoid harmful circulating currents in their secondary windings.
How does current transformer works in a substation?
A current transformer works on the same principle as that of a simple transformer however it steps down the high current into a low level so that it can be measured using an ammeter of a suitable range. In some current transformers extra cores are provided. This is done in order to prevent the faulty currents i.e. the over currents, earth faults, differential protections. The extra cores of a C.T. gets saturated as soon as the faulty currents starts flowing and thereby does not harm the main core of the transformer and the ammeter connected. The C.T. is always connected in the line carrying current. It first steps down the current to a measureable form and further gives this current to the ammeter.
Why the step down transformers are in delta star?
There is no such thing as a multi phase transformer. A transformer has one phase input and one phase output. There may be multiple windings on input and on output, but they are all in phase, insofar as the power factor allows it.What we call a three phase transformer is really three transformers operating together, one on each of the three phases. They do not share the phases. They do not share windings. They do not share cores. They do not share magnetic fields. They are independent. They only thing they might share is they same physical container.Star-delta configuration for three transformers (emphasis on plural) is a common configuration, although star-star is supposed to be better from an eddy current perspective. It comes down to the objectives of the load, and whether or not there there is a neutral involved, and where the neutral is connected. You can still have a neutral in star-delta, but it won't be centered in the middle of the three phase power - it will be centered in the middle of one of the split phase single phases, in the style of 120/240 split phase like typical residential power. Again, it comes down to objectives.AnswerThree-phase ('polyphase') transformers are widely-used in electricity transmission and distribution systems.A three-phase transformer typically comprises a common, three-limb, silicon-steel core, around which are placed three pairs of primary- and secondary-windings, entirely enclosed within a sheet-steel tank containing a mineral oil for the purpose of insulation and cooling. For a delta/wye configuration, the primary winding is accessed through three ceramic bushings, while the secondary winding is accessed through four ceramic bushings.Three, separate but identical, single-phase transformers can also be connected together to create a 'three-phase transformer bank'. Three-phase distribution transformer banks are more common in North America than in the UK, where three-phase transformers are the norm.Most power transformers (i.e. transformers used in the transmission system) are three-phase transformers, although at really high MV.A levels, three-phase transformer banks are used because their very large physical size makes them easier to transport and install.In the UK, distribution transformers normally use the delta/wye configuration, because the high-voltage primary is supplied from an 11-kV three-phase, three-wire, system, while the low-voltage secondary supplies a three-phase, four-wire, system with a line voltage of 400 V and a phase voltage of 230 V.In North America, a three-phase distribution transformer's secondary configuration is normally delta-connected, with one phase centre-tapped in order to supply the standard, split-phase, 240/120 V low-voltage system.
Why current transformers secondary is always short circuited?
Unless a burden (i.e. meters, relays, etc.) is connected to the CT, current transformers should always be shorted across the secondary terminals. The reason is very high voltages will be induced at the terminals. Think of the CT as a transformer, with a 1 turn primary and many turns on the secondary. When current is flowing through the primary, the resulting voltage induced in the secondary can be quite high, on the order of kilovolts. When a CT fails under open circuit conditions, the cause of failure is insulation breakdown, either at the shorting terminal strip, or at the feedthrough (in the case of oil filled apparatus), because the distances between terminals are not sufficient for the voltages present.
Doesn't a transformer work with dc from a generator?
Transformers do not work with DC. Transformers are magnetically coupled inductive devices that operate with AC (fluctuating) voltages. If you supplied DC to a transformer, it would simply look like a short circuit, and the secondary would stabilize to no voltage and no current. This is because, in order to generate a current in a conductor from a magnetic field, either the magnetic field needs to be fluctuating or the conductor needs to be moving.
How do you calculate the of turn and the secondary voltage of the 15kw transformer?
First of all, transformers are rated in volt amperes, not watts. Secondly, in order to determine a transformer's turns-ration, you need to know its primary and secondary voltage ratings.
Can a flyback transformer be powered by nothing but a car battery and wires?
A transformer is an AC device in that it requires a changing current to be input in order to see an output. Attaching a 12V battery to the primary side of the transformer will generate a voltage on the secondary for a short amount of time. Once the primary current has risen to a stable level, there will be no output voltage on the secondary. There will also be voltages on the secondary and the primary when the battery is disconnected from the transformer. A flyback transformer relies on an AC current at the primary to generate a high voltage at the secondary output. Circuitry to make changes to the primary current will be needed in addition to the battery. Warning: removing the battery from the primary winding of the transformer is liable to generate a very high voltage across the primary coil as well as the secondary. In some cases, they can be lethal. Do not experiment with transformers unless you are properly qualified and supervised.
Will transformer operate if a battery is used for the input voltage across the primary?
Transformers only work on a.c. This is because it's necessary to have a changing primary current in order to induce a voltage into the secondary winding.If you connect a battery across a transformer, it will not work. Furthermore, if the voltage of the battery matches that of the rated primary voltage, the resulting very large d.c. current is likely to overheat the primary windings and even burn it out.
Where do you get G1 Transformers?
order them online or get them @ flee markets.
Why do transmission lines use alternating current?
Transmission lines use alternating current in order to support stepping-up and stepping-down of the voltage with transformers. Voltage is stepped-up at the power station, sent over the transmission lines, and stepped-down at the receiver. (This is a simplified explanation.) By stepping-up, you reduce the current carrying requirement of the lines, and they can thus be smaller.You could not do this with direct current as transformers only work for alternating current.
When can voltage be induced but not current?
"Induced" is the verb you are looking for. A current is induced in the secondary circuit by the current in the first changing, provided both conductors are close enough for the driving current's electro-magnetic field to enclose the second conductor. Note that word "changing". Direct current produces a field but that remains constant and does not induce a secondary current, as a.c. does.
How do you select core in Transformer Design?
The material used in the manufacture of transformer cores must have a hysteresis loop with a very small area, as it is the area of the hysteresis loop that determines the hysteresis losses of the core material. The core material should also be resistive, in order to reduce eddy current losses (which is further improved by laminating the core). Many transformer manufacturers use their own variations on what is basically a silicon-steel.A hysteresis curve, or loop, is a graph of flux density plotted against magnetising force, and basically describes the ease (or difficulty) with which the core material can be magnetised and demagnetised as the magnetising current changes magnitude and direction.
Why the windings burn when transformer is operated in DC?
Transformers are not intended to be operated in DC. DC does not provide the continuously fluctuating current that a transformer requires in order to function. On DC, a transformer will act as a transient mode inductor, and settle out to a high current state, destroying itself.
What initiated the change into ac system from dc system?
The need for more and more power. In a fixed voltage system like DC, power is proportional to current, and current is related to conductor size. In order to have more power, you had to have larger conductors, and it was becoming unwieldy. With AC, we could use transformers to step up the voltage. Power is now proportional to both current and voltage, but current is still only related to conductor size, which means that with higher voltage, you could transfer more power with smaller conductors. Transformers would step up the voltage at the substation for transmission and distribution, while transformers on the poles would step it back down for small groups of services.
What are all the Transformers films?
Transformers (2007)Transformers: Revenge of the Fallen (2009)Transformers: Dark of the Moon (2011)There may be another Transformers movie in 2014, according to an interview with Tyrese Gibson.
