Hi ritesh,here is a link for

[AJISH ALFRED]

Hi ritesh,

here is a link for a current sensor (load sensor) which will produce a volatge equivalent output corresponding to the load.

http://circuit-diagram.hqew.net/Self$2dPowered-Current-Sensing-Circuit-%28LT1494%29_21567.html

 

This link will give you the basic voltage level detector circuit diagram

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Cascade these two, so that the level detector detects whenever the output of current sensor rises above a particular level. Replace the led in the level detector circuit with your relay, and thats it !