The zone1 time delay (Z1PD & Z1GD) is generally set to zero, giving instantaneous operation. Zone1 is consid-ered to be the main protection for the line to be protected, hence no intentional time delay is allowed. Further, the duration of the voltage. K2, are the constants, At the balance point, when the relay is on the verge of operating, the net torque is zero hence we can write, Divide By K 2 I 2 on both sides. It is denoted by Z Apply it on the above equation Neglect the spring. The invention provides a dynamic zero drift filtering algorithm for relay protection, which comprises the following steps: (1), inputting a sampling passage into a short circuit, so as to measure an initial zero drift value which is then solidified into a memorizer of the protection device; (2). One of the key challenges in distance protection is the correct setting and calibration of relays to account for real-world variables.