When the configuration is written and completed, the IED is automatically set intonormal mode. For further instructions please refer to the users manuals forPCM600.4.8 Checking CT circuits M12182-2 v15Check that the wiring is in strict accordance with the suppliedconnection diagram.The CTs must be connected in accordance with the circuit diagram provided withthe IED, both with regards to phases and polarity. The following tests shall beperformed on every primary CT connected to the IED:• Primary injection test to verify the current ratio of the CT, the correct wiringup to the protection IED and correct phase sequence connection (that is L1,L2, L3.)• Polarity check to prove that the predicted direction of secondary current flowis correct for a given direction of primary current flow. This is an essential testfor the proper operation of the differential function and directional protectionfunctions.• CT secondary loop resistance measurement to confirm that the currenttransformer secondary loop DC resistance is within the specification for theconnected protection functions. When the measured loop resistance is near thecalculated value for maximum DC resistance, perform a complete burden test.• CT excitation test in order to confirm that the current transformer is of thecorrect accuracy rating and that there are no shorted turns in the currenttransformer windings. Manufacturer's design curves must be available for thecurrent transformer to compare the actual results.• Earthing check of the individual CT secondary circuits to verify that eachthree-phase set of main CTs is properly connected to the station earth and onlyat one electrical point.• Insulation resistance check.While the CT primary is energized, the secondary circuit shallnever be open circuited because extremely dangerous high voltagesmay arise.Both the primary and the secondary sides must be disconnectedfrom the line and the IED when plotting the excitationcharacteristics.1MRK 502 073-UEN A Section 4Starting upGenerator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062 51Commissioning manual
