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Recent content by npower0073

  1. npower0073

    Recloser Vs Circuit Breaker

    I rgink that a recloser is a circuit breaker that opeates with cysles OPEN-CLOSE O-C-O, e.g. when a fault appears the recloser opens, then it tries to close , if the fault is not there it remains closed, if th faults still exists makes another cycle and finally trips open. It is used in overhead...
  2. npower0073

    Steam turbine control issue

    On site , a CCPP with a steam turbine Franco Tossi Mechanica and Siemens ORSI IT control system we experience lateley the following event: WHile ST runs her start up sequence the speed is controlled by HP Stop (throttle) valve). After the spped of 2800 rpm the conmtrol of spped goes to HP...
  3. npower0073

    Tap changer oil samplig

    This week we made the tap cahnger inspection, it was almost new, no sign of overheating or whatever else. Seems we have to reconsider the need for gas analysis.
  4. npower0073

    GT 9FA increased proximity readings at TE of generator

    The repalcement of cross fire tubes did not solve the problem of vibrations.
  5. npower0073

    Tap changer oil samplig

    an isoaltin and earthing, we lokked and found air on the bucholz relay of tap chager compartment, also there was air when we vented. But the oil (probably due to the filter ) was almost clear.
  6. npower0073

    Tap changer oil samplig

    isquaredr , The diverter switch is not separate from the tap changer, is separate from the main oil tank.
  7. npower0073

    Tap changer oil samplig

    subtech , the oil was new, not from another transformer but from new drums. prc, i mean oil from the tap changer diverter switch tank. THe BDV is very good, 60kV and higher. defreitas, I have not seen any carbon in the oil. BUT during the first 30 months of transformer operation there was no...
  8. npower0073

    GT 9FA increased proximity readings at TE of generator

    Last week we made a repalcement of the piping ofcross fire tubes , all the flanges on these tubes were in very bad wuality. After these works the comaprtment temperatures dropped from 180 to 115 degrees Celsius.
  9. npower0073

    Tap changer oil samplig

    The results from the oil sampling show very good dieelctric strength but increased concentration of gases. Find below the resutls from two concequtive sampling Hydrogen(H2) (ppm,w) 3414 25075 Oxygen(O2)(ppm,w) 8492 7452 Nitrogen(N2) (ppm,w) 120665 35969 Carbon monoxide (CO)(ppm,w) 14 148 Carbon...
  10. npower0073

    HP Drum level measurement

    roydm, thanky you very much for your post, we use on site the three element level control. And it works OK, during ent big outage we will combine the revision of the transmitters span as well.
  11. npower0073

    Exciter EX2100 code 53 alarm and transfer blocking

    On site we have one Ge generator 325MVA 4-pole hydrogen cooled with static excitation system EX2100. We experience alarm code 53 fault, and M1 controller reads different current magnitude than M2 so it goes to transer block and we loose redundancy. There is a product bulletin from GE that says...
  12. npower0073

    Tap changer oil samplig

    edison123 , we made work on the spring contacts of the diverter switch.
  13. npower0073

    Tap changer oil samplig

    On site we have a three winding step up transformer 440MVA, 400kV/15.75kV/15kV. Lately we made maintenacne on the tap changer (MR), changed the oil and put back in service. After 10 days we made ne oil analysis and after 40 days we made a second oil analysis. The results of the first analysis...
  14. npower0073

    HP Drum level measurement

    hacksaw unfortunately the sight gauges are not working correctly and we are in the process to repalce them
  15. npower0073

    HP Drum level measurement

    Our HRSG is a triple pressure one with an HP Drum that works at pressure of 115 bar at base load of gast turbine. During recent overhaul we saw that the actual level of the drum (red marks on the inside of the level drum) is almost 100 mm higher than the designed one. THe level is measured with...
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