A11kV HRC Fuse is used to protection 1500KVA oil insulated distribution transformer with 5% impedance volt....

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A11kV HRC Fuse is used to protection 1500KVA oil insulated distribution transformer with 5% impedance volt. The transformer is the delta (11kV) - star(380/220V) connected with LV side neutral solidly connected to earth. The operation characteristics of the HRC fuse is shown below as extract from fuse supplier catalogu Time/current characteristics curves 3.6-7.212 17.5-24-36kV Time (s) The upstream of the transformer has an 11kV circuit breaker with the following overcurrent protection adopted to provide protection to 11kV cable as well as transformer 11kV fault. a. A LV L1 - L2 - E a phase-to-b phase - to earth fault occur after the ACB connected to the transformer LV. Earth fault resistance 0.001ohm. i. Assuming infinite busbar at 11kV, drawing sequence network for PPS, NPS and ZPS and then calculate 1, 1, and I for the LV fault. ii. Calculate LV fault current la, lb, IC and earth fault current le that will be seen by 2500AACB OCEF relay. Calculate the relay operation time of the OC and EF relay. Relay settings are: - 2500A Overcurrent, Extreme Inverse, Plug setting multiplier = 1, Time Multiplier Setting = 0.1 2500A Earth fault relay, Normal Inverse, Plug setting multiplier = 0.1, Time Multiplier Setting = 0.1 A11kV HRC Fuse is used to protection 1500KVA oil insulated distribution transformer with 5% impedance volt. The transformer is the delta (11kV) - star(380/220V) connected with LV side neutral solidly connected to earth. The operation characteristics of the HRC fuse is shown below as extract from fuse supplier catalogu Time/current characteristics curves 3.6-7.212 17.5-24-36kV Time (s) The upstream of the transformer has an 11kV circuit breaker with the following overcurrent protection adopted to provide protection to 11kV cable as well as transformer 11kV fault. a. A LV L1 - L2 - E a phase-to-b phase - to earth fault occur after the ACB connected to the transformer LV. Earth fault resistance 0.001ohm. i. Assuming infinite busbar at 11kV, drawing sequence network for PPS, NPS and ZPS and then calculate 1, 1, and I for the LV fault. ii. Calculate LV fault current la, lb, IC and earth fault current le that will be seen by 2500AACB OCEF relay. Calculate the relay operation time of the OC and EF relay. Relay settings are: - 2500A Overcurrent, Extreme Inverse, Plug setting multiplier = 1, Time Multiplier Setting = 0.1 2500A Earth fault relay, Normal Inverse, Plug setting multiplier = 0.1, Time Multiplier Setting = 0.1

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SOLUTION To solve this problem and calculate the fault currents and relay operation times we need to perform certain calculations based on the given information Lets go step by step Step 1 Drawing Seq... View the full answer