The simple answer is "NO". Whatever is tapped-off of the secondary, or otherwise modified, does in no way diminish the laws of transfer of power from one winding to the next, or available potential. Whatever is actually realized at the secondary will never be 100% of the input due to losses in transfer, such as heat losses. * I'm still not sure but having thought about it more I now think that if you increase the resistance in the secondary circuit and therefore decrease the secondary current, without changing either voltage, the power on the secondary would fall with the current. The primary power would also have to fall to remain equal to the secondary power (heat losses aside), and the primary current would also fall. Is this correct? Thanks Yes. Because a transformer is very efficient, power measured on each side is almost the same. P = VI = vi The voltage ratio V/v depends on the number of turns in the windings and is therefore constant. Decreasing resistance on the secondary side allows an increase in the current. Current on the primary also increases because power in is equal to power out.
A 'current transformer' is a type of transformer which, together with a 'voltage transformer' (or 'potential transformer' in N America), is classified as being an 'instrument transformer'. It is used to reduce large currents to smaller currents which can be measured safely, and to isolate the primary circuit from the secondary circuit for the purposes of safety. Current transformers are also used to drive protective relays used in high-voltage protection systems.
why does have to short-circuit secondary wire of current transformer ?
A Linear power transformer coil? use an Ohm meter and check the resistance of the coils. No resistance is an open circuit. Also check for a cross circuit from one side of the transformer to the other.
If you are saying that the secondary (output) winding on a transformer seems to be a short circuit, it is very likely to be low resistance and may only be a few ohms if you measure the resistance with an ohmeter. The only way it would actually be a short circuit is if something has been inserted which has shorted the wires or it has overheated and burnt through. In which case there should be an acrid smell. Or if you can see the wires you would see they were burnt. A short in the circuit it is powering could cause the transformer to overheat, burn out and short.
Secondary circuit burns out, causing serious damage to transformer.
Such a transformer is called an 'isolation transformer' and, as its name implies, is used to electrically-isolate the secondary circuit from the primary circuit.
Winding copper losses of a transformer can be measured in a short circuit test of a transformer. Impedance voltage is given to the primary and the secondary is often shortcircuited. (some times the reverse is done of this). Full load currents are made to flow in both primary and secondary circuits. This current flow heats up the 2 windings of the transformer. Power consumed at this time gives the transformer copper losses.
Current doesn't 'pass through' a transformer. There are two currents: a load (or secondary) current and a primary current. To measure these you would have to use two ammeters: one in the primary circuit and the other in the secondary circuit. If we are dealing with high voltages, then we would need to insert current transformers into the primary and secondary circuits, and use them to supply our ammeters.
The function of an isolation transformer is to electrically-isolate the secondary circuit from the primary circuit, without changing the voltage levels. So, its secondary voltage will be the same as the primary voltage.
A short-circuit test is done to determine the power lost in the resistance of the primary and secondary windings of the transformer. It is done at full load current but with only enough voltage to give the required current with the secondary short circuited. An open-circuit test is done at full load voltage but no current is taken from the secondary, and this enables the power lost in the magnetic core of the transformer to be measured. As well a power, the tests also allow the inductances to be measured as well as the resistances, in order ot characterise the transformer fully.
The most important advantage is that the secondary circuit is electrically-isolated from the primary circuit.
The resistance of the winding in the primary of a transformer constitutes a load. As long as there is resistance then there is no short circuit. A short circuit is considered no resistance which develops an instantaneous high current. That is why fuses and breakers are inserted into the circuit to open the high current flow under a short circuit condition.
To electrically isolate the secondary circuit from the primary circuit, without changing the voltage.
A: i am afraid of a voltage transformer is not a good description of a power converter That is what a transformer does it convert power [minus effefiency ] from one source to another. A shorted primary or secondary will eventually destroy the transformer if exceed the transformer power dissipation Some transformer are used for specific purposes. Current transformers are designed so they attempt to push a ratio of the current in the primary through the secondary. For this reason the secondary is typically loaded with a small resistance; an open circuitted secondary will cause the transformer to attempt to push the secondary voltage up to primary voltage potential (often thousands of volts); Never open the secondary of an active CT. A potential transformer, on the other hand, should not have the secondary shorted. A short will overload the transformer; they are designed to provide a reflection of the primary voltage, and so the secondary is usually loaded with a large resistance (so low current flow); this is why the secondary is typically fused with relatively small fuses.
Due to inductive behaviour of the circuit, current should go up towards infinity, but resistance and temperature will rise and destroy the transformer.Transformers must be driven by a null mean voltage.Result will depand on the resistance of the transformer. For DC transformer is simply a low resistance circuit if connected DC voltage is much high as compared to transformer resistance then it will cause burning of transformer's windings.
Measurements of electric currentsAnswerA current transformer allows high values of a.c. current to be measured using an ammeter designed to measure lower-values of a.c. current. At the same time, it electrically isolates the primary circuit from the secondary circuit -essential if the primary circuit is part of a high-voltage system. CTs are also used to monitor primary currents for the operation of high-voltage protection relays.
A secondary current of 0 would suggest to me that the secondary circuit is open. A normally operating circuit with zero current flow would be very unusual. No load in secondary circuit. No secondary current can also be attributed to the primary power source open or an open primary winding.
I'm not sure that it is correct to say a transformer limits current under no load (maybe it is, depending on your application).A step down transformer converts a high voltage at the primary to a lower voltage at the secondary. Under no load conditions, the secondary will be an open circuit. Since The primary current relative to the secondary current will be Np/Ns (the turns ratio, primary to secondary), and the primary voltage relative to the secondary is Ns/Np, the apparent resistance at the primary due to an open at the secondary will be (Np/Ns)^2*(open circuit). Since an open circuit is typically approximated as an infinite resistance, resistance is infinite. The turns ratio in this idealized example doesn't really matter, hence the transformer doesn't really matter (only the fact that a no load means an open secondary matters).AnswerUnder no-load conditions, the primary current is limited due to the voltage induced into the primary winding, which opposes the applied voltage (Lenz's Law).
An 'isolation transformer' is a 1:1 ratio mutual transformer. It electrically isolates the secondary circuit from the primary circuit without changing the voltage level. A bathroom shaver socket uses an isolation transformer.
Generally speaking, equivalent circuits are used to simplify a complex circuit into terms that are solvable with known relations. For example, in a transformer equivalent circuit you can account for winding losses and flux leakage with a series resistance and reactance on the primary side. Core losses can be modeled similarly with a parallel resistance and reactance on the primary also. Essentially when reflecting/referring an impedance to the primary side of a transformer, you are just seeing what the secondary impedance "looks like" to the primary side. Since the secondary impedance will determine the load on the primary, it is helpful to know how to relate it in terms of the primary so as to calculate the current flow in the primary due to the load on the secondary.
If you take a power source like a dc battery or AC transformer secondary winding and connect an ammeter directly across these power sources you can read the short circuit current available from that source. This gives a measure of internal resistance of the battery or the available wattage of the transformer.
Use Ohm's Law. In this case, multiply the resistance by the current.
A transformer or, more-properly, a mutual transformer, has two windings, the primary and the secondary, which are electrically-isolated from each other, with the secondary voltage induced through mutual induction. An autotransformerconsists of one tapped winding, so the secondary circuit is not electrically isolated from the primary circuit. An autotransformer may be used to either increase or decrease the primary voltage, depending how it is connected.
depends on the type of trans former.buck or boost.primary winding a secondary winding
The current in the Primary circuit will rise to an unsafe level.