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I have some questions about the operation sequence when the wood chip biomass fired boiler trips and need to shutdown. When the boiler is tripped as a emergency case and the normal AC power supply is unavailable as it is totally black out, since the fuel feeder is screw feeder, during shutdown...

What is the difference between GLBS(generator load break switch) and GCB(generator circuit breaker)applied to power plant porject. I got caught with contractor that they proposed GLBS to be used for 1000MW coal fired power plant instead of GCB. The plant is connected to 500kV switchyard and has...

Hi, I wonder why the IEC60076-5 requires that the system source impedance be added up to the transformer short circuit impedance and used in calculating the through fault current for transformer damage curve instead of using only the transformer impedance ? When the %Z of transformer was fixed...

Hi, I have question related to transient stability for 4x GTG(GE frame 6B,40 MW each. There are 4 x GTGs operating connected with utility power grid at 115kV. During normal operation, power plant has captive loads at 50 MW and the surplus will be exported to grid. When line to utility is...

Hi, I got the query from customer that; they operate diesel generators(4x5.9MW)to supply power to their customer cement plant. Their customer also has 1x4MW steam turbine generator. The problem is that their customer's loads vary between 2-4 MW and customer's steam turbine runs at 4MW base load...

Hi, I have read NFPA20 which requires that the thermal overload is not required to protect the motor but the locked rotor protection is required. I have question about the electric fire pump locked rotor protection. Is it necessary that the protective relay curve needs to lie below motor safe...

I have the problem in designing lightning protection of above ground water storage tank as follows; I designed lightning protection based on NFPA780 standard. The tank has more than 5 mm. thickness. So I do not have air terminal on the top of tank but uses the tank itself as striking...

I would like to know whether tank having thickness > 5 mm with platform and handrail around the top perimeter of tank needs air terminal for lightning protection or not ? In case a tank alone without handrail, it is clear that the tank itself is self protection but with handrail around top...

Hi, I would like to know how to calculate the numbers of consecutive starts of motor. Is there any publication telling about this ? As I know, numbers of consecutive starts depends on mechanical drive moment of inertia. The more mechanical drive moment of inertia, the less numbers of...

Hi, I have the question about the IEC standard kW rating since I got the proposed motor rating 380kw instead of 400 kW and 420kW instead of 450kW. As I check with the European well-known motor manufacturers e.g. ABB, Siemens, their standard motor kW rating seems to be standardized and are the...

I have some question about generator circuit breaker according to IEEE C37.013 standard. GCB manufacturer indicates two symmetrical interrupting capability for example Siemens Type 3AH38 as follows; Symmetrical interrupting capability; -system source side = 50kA (IEEE C37.013 section 5.8.1)...

I wonder that whether the turbo generator grounded through MV resistor can be used to detect 100% stator E/F or not ? I have checked all my previous projects using 100% stator E/F and found that all these generators have neutral grounding transformer with resistor connected at secondary side...

Hi, I have seen the standard generator single line diagram of Siemens always shows the surge arrester between generator neutral grounding transformer and ground for gas turbine generator started with static frequency converter. The question is that why the arrester is need to be connected...

Hi, I have seen the standard generator single line diagram of Siemens always shows the surge arrester between generator neutral grounding transformer and ground for gas turbine generator started with static frequency converter. The question is that why the arrester is need to be connected...

Dear All, Have anyone experienced the problem in comparison between the calculated Idc system short-circuit current and circuit breaker rating using IEC standard ? I have one small power plant project which the owner had bought several small generators size from 8MVA to 17MVA and connected to...

Hi, I have the question regarding to the HV/MV short-circuit rating of circuit breaker. According to IEC standard, the following short-circuit rating of circuit breaker will be used in comparison with the calculated short-circuit current to verify whether such CB have sufficient short-circuit...

Hi, I have the question regarding to the MV short-circuit rating of circuit breaker. According to IEC standard, the following short-circuit rating of circuit breaker will be used in comparison with the calculated short-circuit current to verify whether such CB have sufficient short-circuit...

Hi, I am power plant engineer, now I am designing 300MW coal fired power plant. The consultant request to submit calculation for sizing excitation transformer. Can anyone advise me how to calculate excitation transformer size for static excitation system of turbo generator ? Thank you...

Dear All, I have one question regarding to the CT sizing for phase overcurrent relay. The question is that the CTs used for motor feeder normally is dimensioned based on continuous current of motor. For example motor 320kW, 6.6 kV, the 5P20 class,50/5 A CT 15VA is selected while the max...

Dear All, Does anyone have experience with turbine generator cooling like this ; Stator : Inner Water-Cooled. Use water flowing inside copper tube conductor. Rotor : Air-cooled. I have received the proposal from China manufacturer which they deviate the 60 MW STG from air-cooled to this kind...