BANGLADESH POWER DEVELOPMENT BOARD TENDER ... - BPDB

Special measures may have to be taken to ensure that the core is fully demagnetisedbefore commencing the test.aPrimary InjectionPrimary current injection tests shall be carried out by the Contractor. The primaryinjection methods employed for a particular installation shall therefore be agreedwith the Board.Tests shall be carried out as follows:--Local primary injection to establish the ratio and polarity of currentTransformers of similar ratio.-Overall primary injection to prove correct inter-connections betweencurrent transformer groups and associated relays.-Fault setting tests to establish, where practicable, the value of currentnecessary to produce operation of the relays. If not practicable, thesetests are to be carried out by secondary injection applied at the wiringclose to the current transformer.(3) DC OperationsTests shall be carried out to prove the correctness of all DC polarities, theoperating levels of DC relays and the correct functioning of DC relay schemes,selection and control switching, indicating and alarms.(4) On Load TestsIn view of the hazards inherent in these tests, they shall be carried out under thedirect supervision of the Board & Engineer.An operation and stability test shall be carried out for on load commissioning ofunit type protection.Test for restraint shall be carried out to prove the characteristics of protectivesystems with directional/differential characteristics,On load checks shall be made after the protection gear has been placed in serviceto ensure that all connections and test links have been replaced and test leadsremoved, as well as to confirm the integrity of the current transformer circuits.Where necessary voltage readings shall be taken at the terminals on each relay &meters to ensure that loop connections between the relays & meters arecomplete. Special attention shall be paid to broken delta voltages and residualcurrent circuits where zero voltage or current respectively may not be proof of thecompleteness of the circuit.(5) Step-up Transformersa. General mechanical checks.b. Core and winding insulation tests.Ghorasal 200 MW to 300 MW Gas Turbine Peaking Power Plant Project (Vol-2 of 3)150