Rephrase your question so that it makes sense.
Transformer rating is based on the maximum temperature a transformer can run at. This temperature is dictated by the amount of current flowing through the transformer windings. This is why transformers are rated in KVA (voltage * current), not kW - it doesn't matter what the phase relationship is between voltage and current, just the magnitude of the current.
in welding machine, the transformer used is basically a current transforrmer. so by changing the tap of secondary side of transformer, we can increase or decrease the current in the transformer.
why does have to short-circuit secondary wire of current transformer ?
I am assuming the question is about the power / distribution transformer and not the current transformer. The primary current is a function of load connected on secondary. With the open secondary, there is no load, no current, it is open circuit. Hence no primary current. However there is always some small amount of no load current in the primary winding.
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.
Transformer rating is based on the maximum temperature a transformer can run at. This temperature is dictated by the amount of current flowing through the transformer windings. This is why transformers are rated in KVA (voltage * current), not kW - it doesn't matter what the phase relationship is between voltage and current, just the magnitude of the current.
The transformer itself does not pull current. Whatever you connect to the transformer pulls current. Whatever the output voltage of the transformer is, divide that into 600 and you get maximum current possible without burning up the transformer. At 24V that's 25 amps.
AC current or DC current can be used in transformers. A transformer is made of two coils of wire, the input coil induces a current into the output coil. Transformers change the voltage either up (step up transformer) or down (step down transformer). The amount of change in voltage is dependent solely on the number of windings in both coils in the transformer. DC transformers work exactly the same way AC transformers do.
The primary current of a transformer depends upon the secondary current which, in turn, depends upon the load supplied by the transformer. There is not enough information in the question to determine the rated primary and secondary currents of the transformer.
in welding machine, the transformer used is basically a current transforrmer. so by changing the tap of secondary side of transformer, we can increase or decrease the current in the transformer.
why does have to short-circuit secondary wire of current transformer ?
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.
I am assuming the question is about the power / distribution transformer and not the current transformer. The primary current is a function of load connected on secondary. With the open secondary, there is no load, no current, it is open circuit. Hence no primary current. However there is always some small amount of no load current in the primary winding.
The correct symbol for kilovolt amperes is 'kV.A, not kva. A volt ampere is the product of the transformer's secondary rated voltage and its rated current. It is not rated in watts, because the transformer designer has no idea what sort of load is to be applied to the transformer, and it is the load that determines the amount of watts, not the transformer.
It is a transformer with No load attach to it.
A current transformer is primarily used at the neutral point of a transformer for earth fault protection. A neutral current transformer will measure any ground fault current which will essentially flow from the star point of the transformer. A fault-detection device other devices is connected to the current transformer and, if the fault current exceeds a certain trigger value, the fault-detection device will give a trip command to an earth-fault relay to disconnect the supply of electricity to the transformer.
Yes, the two things that chage the number of flux lines in a transformer(electromagnet) are the number of turns in the windings and the amount of current flow