regarding the action of stepdown voltage transformer

when we used step down transformer,on the secondary side voltage is low and current will be high. My doubt is that high value of current will damage the equipment or the input current of transformer is low?

It would be helpful if you could provide more information about what transformer you are using and what equipment is being powered.

You are correct that if a transformer is used to step down a voltage, the secondary current will be higher than the primary current. After all, in an ideal transformer Vs/Vp = Ip/Is. I think where you are getting confused is about the actual values of the primary and secondary currents. The secondary current will be dictated by the amount of current your equipment draws. The transformer cannot source more current than your equipment draws. If there is nothing connected to the secondary side of the transformer, the secondary current will be zero.

If you ensure the secondary voltage of the transformer is within the acceptable input voltage range for your equipment, and the transformer can handle the load, your equipment shouldn't be damaged by high currents.

Or else, I'm completely misunderstanding your question:wink:

If voltage is right for your device then it won;t be damaged. Transformer secondary is CAPABLE of large current as opposed to FORCING a large current.

Your question need more elaboration.
When the transformers are designed for a particular equipment the wattage of the supply is considered as per equipment demand. If the transformer is having the required voltage and not more the connected device won't damage, as the only demanded current is supplied but if the transformer is lower in wattage per the equipment demand it may damage.

normally what will be the current values for step down transformer(11KV/230V) before and after operation.We know that V2/V1=I1/I2,so what about the current ?

In power transmission also we will say that 230V but why we wont discuss about the value of current ?

Because the Current is load dependent on the specified voltage of the circuit. Transmission line is kept on high voltage to reduce the line losses as the current will be lowered as we take the voltage higher (W=E.I). The Generator is specified always on the wattage and the voltage being generated, so the output of the generator will remain same till we increase the capacity of the generator in wattage. We increase the voltage for the purpose of transmission and to lower the line losses decreasing the current..

watt output= watt input,if yours transformer's handling capacity i.e vi more than the demanded capacity the there'll no damage.if u mean the transmission line,the voltage is kept high to reduce the line losses.