Answer / parag mohanty.

upper impedance is the impedance above which distance relay
will not operate and lower impedance is below which it will
not operate

Answer / bl meena

upper-above which not operate
lower-below which operate

Answer / srikrishna kumar

the operation of the relays depended upon the magnitude of
current or power in the protected circuit. however,there is
another group of relays in which the operation is governed
by the ratio of applied voltage to current in the protected
circuit. such relays are called distance or impedance
relays. in an impedance relay, the torque produced by a
current element is opposed by the torque produced by a
voltage element. the relay will operate when the ratio V/I
is less than a predetermined value.

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