Section 3: − Added OPO Open Pole Option (52,27). Sample calculation-for-differential-relays 1. R R is relay burden V S = I (R CT + R W + R R) Where I is the fault current and V S is the ct secondary voltage. Subject: Investigation of recent trippings of power transformer on Harmonics in differential relay for taking corrective action to prevent further trippings. Filter Design Calculation; P63x Differential CurrentsCalculation MiCOM P634/P633/P632; Calculating the operation current in Bias Differential Relays MiCOM P633; POINT-TO-POINT METHOD OF SHORT CIRCUIT CALCULATIONS; SLOPE CALCULATION OF LINE DIFF RELAY P543; TMS Calculate Differential Protection Setting Calculations Where R CT is CT burden (internal) R W total resistance of the ct secondary wiring. Application Example on Transformer Differential Protection Calculation 25/33MVA 69/23kV Delta-Wye Transformer on SEL-387A Relay Figure 1. transformer protection application guide ieee. Here we are showing a simple example to get an idea of basics for relay setting calculation. Section 2: − Updated table SEL-311L Relay Line Current Differential Electrical Interface Cable Application. In order to make sure that the ct is in the linear range (to avoid ac saturation of the ct’s), V 2 : Model setting calculations -Line 1-149 3 : Model setting calculations-Transformer 1-132 4 : Model setting calculations- Shunt Reactor 1-120 5 : Model setting calculations- Busbar 1-15 6 : Relay setting guide lines for transmission lines 1-19 7 : Recommendations for protection system management 1-5 From current setting we calculate the trick current of the relay. Protection Relays Differential Relays 1- Using stabilizing resistor: a) Low Impedance Differential Protection : Under external fault condition, the protection must remain stable and should not operate, even if one C.T. has completely saturated. − Corrected references to figures in Section 3 in Relay Element Settings Ranges and Accuracies. Say current setting of the relay is 150 % therefore pick up current of the relay is 1 × 150% = 1.5 A. Step-3 Now we have to calculate PSM for the specified faulty current level. Differential Relays 2. The bias slope limit is chosen to ensure the biased differential function is stable for high through fault currents coincident with CT saturation. Setting calculation: We will drive settings for Station-A end relay of a 220kV line to station-B. Calculation: Differential Relay setting calculations of the Power transformer based on Typical Power Transformer data as mentioned below: Data: 1. overload relay setting and calculation electrical. For that, we have to first divide primary faulty current by CT ratio to get relay faulty current. what to know about protective relays electrical. relay settings. Actual relay setting calculation will depend on many factors like relay make and model, network size etc. This setting is primarily needed to prevent operation of relay in case of through fault results saturation of CTs causes a transient differential current to be detected by the relay. ref relay setting calculation blogger. The length of a line can be defined by physical distance, impedance, or its source impedance ratio (SIR). guidelines for relay settings at traction. IDMT Relay High Current setting :Plug setting of Relay is 2.5 Amp and Time Delay (TMS) is 0.100 Sec, Relay Curve is selected as Normal Inverse Type; Calculation of Over Current Relay Setting: (1) Low over Current Setting: (I>) Over Load Current (In) = Feeder Load Current X Relay setting = 384 X 125% =480 Amp − Corrected ETAP setting indicated in Differential Element Settings and Specifications. Transformer Vector Group and CT to Relay Connection. differential relay electrical4u com. 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