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Difference between potential transformer and current trasnformer?
The difference between current transformer and potential transformer is that the secondary of a current transformer can not be open circuited while under service whereas that of the potential transformer an be open circuited without any damage to the transformer.
What is the function of the primary current when the secondary winding of the transformer is open?
When the secondary of a transformer is opened, there is no longer any load on the transformer. There will be some current flowing in the primary winding, which is needed to induce the voltage in the secondary. This primary current is referred to as the "no load" current, and is indicative of the core losses in the transformer.
How to test Excitation Current of a transformer?
To test the excitation current of a transformer, you can perform an open-circuit test, where the primary winding is connected to the rated voltage while the secondary winding is left open. Measure the current flowing through the primary winding using an ammeter; this current is the excitation current. It's essential to ensure the transformer is at the specified voltage and frequency during the test for accurate results. Additionally, record the voltage and power factor for further analysis if needed.
Why open circuit test is done on the transformer with low voltage side shorted?
The supply is given on the high voltage side of transformer because the supply voltage required to circulate rated current through the transformer is usually very small So energy is saved.
Why should the secondary of a voltage transformer not be short circuited?
A voltage transformer takes a primary voltage and steps it down to a smaller secondary voltage. This type of transformer will attempt to keep the secondary voltage at a specific ratio of the primary voltage. If you short it, massive current flow in the secondary is required to do this. For a similar reason a CT should never be open circuited - because it attempts to push a specific ratio of primary current through the secondary. If you open circuit the secondary, it takes a massive voltage on the secondary to accomplish this.
Why keep a voltage transformer secondary open?
it is keep open so as to supply voltage to the loadAnswerThe secondary winding of a transformer is NOT necessarily kept open, unless you want to disconnect its load.
Why secondry of current transformer should not be open?
A current transformer will always attempt to push a ratio of the primary current through the secondary. So if there is primary current flowing, and you open circuit the secondary, the CT will attempt to build up voltage to the point where the correct amount of secondary current can flow through the open circuit (meaning you will get an arc). If it succeeds, you'll have a bright light, and some melted copper, and a very startled person who was unfortunate enough to open circuit the CT. This high voltage can also damage or ruin the CT.
What is short circuit voltage?
Short circuit voltage is the voltage that has to be applied to the primaries of a transformer, so that the nominal current flows through the secondaries, when they are shorted. This value is important, if transformer secondaries shall be used in parallel. Ideally all transformers with parallel secondaries should have the same short circuit voltage. When their short circuit voltages are different, the transformer with the lower short circuit voltage will be loaded more than their relationship of power ratings would predict. The short circuit voltage is also important in the design of a transformer, because it predicts, how much the secondary voltage will drop at nominal output current. This knowledge helps the designer to find out, how many further windings the secondary needs for a certain voltage in relation to an ideal transformer. Short circuit voltage is also known as impedance voltage.
Can infinite voltage be given at transformer primary?
no, infinite voltage can't be given to the primary of the transformer....if the secondary is connected to the load, then over voltage will damage the load, if secondary is open circuited, then the infinite voltage can breakdown the transformer internal insulation,
Is it necessary to connect a fuse at the secondary side of a current transformer?
Definitely NOT! An open circuit (across a melted fuse for example) on the secondary side of a current transformer is subject to a dangerously-high voltage, so a fuse must not be fitted. The secondary side of a CT must never be open circuited.
What are the approximation of open circuit and short circuit test of transformer?
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.
What is the role of magnetizing current in transformer?
connect 3 - phase supply to transformer primary winding.....keep transformer secondary winding open..... apply 3-phase voltage i.e.400v ac, and measure the amount of current flowing in each phase of the transformer primary winding...this current is the transformer magnetising current..... we can keep multimeters in series with the source....so we can measure directly the current readings.....(keep multimeters in current mode, and generally magnetising current will come in terms of milli amps for 400 v )
