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Recent content by loadangle

  1. loadangle

    Transformer overexcitation protection (24) on HV side?

    If the transformer is supplied with tap changer the protection must be connected to a side without tap changer. The side with the tap changer can withstand different voltages depending on the tap changer position and is therefore not suitable for overexcitation protection.
  2. loadangle

    UPS battery low

    we have 15 kva ups one master one slave up with 20 nos 12v ni-cd battery for each UPS.problem has been solved. one of the battery of master ups had very low voltade(internally got opened),detected during load test...replaced it..now alarm went.our power plant DCS system is supported by this UPS...
  3. loadangle

    Generator power factor fall...

    Again thanks all of you for analysis.I am triyig to answer all the questions mentioned above in this segment. 1)YES WE HAVE AN OLTC OF GENERATOR-TRANSFORMER UNIT OF 15MVA(11/66kV)LOOP-IN-LOOP-OUT.but the RTCC panel is located near switch-yard at 150 meters distance from power plant.we dont...
  4. loadangle

    UPS battery low

    my master UPS showing battery low alarm,which is not getting reset,battery test button is also not working.but battery voltage is 430v tested by multimeter & 8 Amps load is on master UPS.few days back same problem came to my SLAVE UPS.but we done battery test & low battery alrm went away.what...
  5. loadangle

    Generator power factor fall...

    sir I am from India.no reactive power flow status available in our DCS.trends of power,frequency,turbine speed,voltage,current,pf are available.the falling of Pf didnt start instantly after synch,it took few time then suddenly fell.the machine behaved like this for the first time in the same...
  6. loadangle

    Generator power factor fall...

    thank you so much all of you, for your kind guidence.yes after meeting the plant load extra power is pushed into grid.in this situation grid & generator breaker in closed position as you mentioned.but all you said is true.contact of grid bkr has been used for avr for letting it know that grid...
  7. loadangle

    Generator power factor fall...

    our AVR alaways stays in PF mode when connected to grid,normally operating the gen at 0.90 lag, when we are connected to grid
  8. loadangle

    Generator power factor fall...

    just after synchronizing our power plant's turbo generator with grid when load gradually incresed & we satarted exporting,PF was near 0.86 lag & everyting seemed stabilize, suddenly we noticed sharp fall in generator power factor & rise in generator amps.we have steam turbine,brushless...
  9. loadangle

    HT MOTOR HAVING HUMMING NOISE

    at last we had a shut down & the motor was overhauled.While taking measurements of both end shield covers we found offset of 0.10mm in front shield & 0.15mm offset at rear end shield covers.Due to this ovality of both end shield the rotor was not in magnetic center,thus causing humming...
  10. loadangle

    HT MOTOR HAVING HUMMING NOISE

    The possible causes mentioned above are been taken into account while checking.WE have checked the bearing with BEARING analyzer which I have mentioned earlier & all the values ware satisfactory.There is no temp. rise on DE or NDE side of the motor.So we can rule out the possibility of wrong or...
  11. loadangle

    HT MOTOR HAVING HUMMING NOISE

    dear no rewinding work done in that motor only varnishing done.
  12. loadangle

    HT MOTOR HAVING HUMMING NOISE

    we have BOILER FEED PUMP MOTOR OF 300kw HT(3.3kV)directly connected to VCB.Recently after overhauling we are encountering an abnormal humming noise from the motor.Temp of DE & NDE side bearing is very normal as both side bearing has been changed & sleeving done at both side shied bearing...
  13. loadangle

    siemens micromaster 440 vfd

    no dear only the torque signal to remote pid is bypassed..no issues with vfd performance. its not co incidence by the way.I faced tripping off this vfd with HIGH torque alarm many times previously..I am just trying to find out the missing links between all those tripping & shutdown incidences...
  14. loadangle

    siemens micromaster 440 vfd

    first of all thanks for responding to the post, mates. let me tell you few things... 1) the dust is conductive. 2)the vfd can not be moved in other place because it runs a screw extruder machine..bulky in size.it got to stay in lab where it is now. 3) the vfd HMI is mounted on vfd body,with no...
  15. loadangle

    siemens micromaster 440 vfd

    I have a Siemens micro-master 440 vfd to control a 7.5 kw,1400 rpm induction motor.now the problem is after running for few days it stops automatically without showing any fault & doesn't accept start command for next few hours or so until i clean it with air.I have replaced the drive two...
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