sorry the diode placement is a mistake in the sch.
the purpose of doing this is to make sure that the o/p of relay should be NC normally but it should open if there is power failure,
i can use NC of the relay with some device to act as NC if there is power, but i thinkif i use a NPN as a switch connecteing base to vcc and let the C and NC of relay at Collector and emmiter, the problem i would face is that i should use GNd... but C can be from any other circuit.. is there another solution?