Thanks for all advices above.
The combustion process is the stoker fired. I still have some questions as below;
1. How about when the plant is subjected to emergency trip ? if the minimum plant safe shutdown requires to continue running BFP, how about other fans such as secondary air fan and...
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...
waross, I understand that point but I am thinking that is it correct that after field CB trip, there is no decaying current anymore. The current becomes zero immediately. So no effect to equipment that the short circuit happened.
My understanding is that even though the field CB has tripped...
Is it true that when the field CB has been tripped, the there is no decaying fault current from generator anymore. The fault current from generator is totally abruptly zero. This is the contractor clarified.
Between tripping field CB and not tripping field CB, what is the difference of decaying...
They will design too have protection zone covers GSUT and UAT. Fault at any these equipment i.e. generator, GSUT, UAT, IPB will cause tripping of 500kV, 11kV incomer CB and generator field breaker.
The reason that contractor used is that without GCB, even there is no GLBS, there is no harm to...
Thanks ScottyUK,
Yes, you are right. However apart from view point on the plant operation and cost, in terms of safety/damage to the equipment,it seems that there is no issue ?
In order to justify to contractor reasonably, I have the following issues to be considered, kinldy advise me if I am...
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...
One thing I thought is that it might be because the Var exporting increases (active power is zero or negligible, from V-curve of generator, at zero power factor the field current increases and armature current increases. This might be one reason since the losses will be higher even though the...
At starting up of diesel generator, yes it needs active power to spin it off from standstill. This certainly requires fuel.
But the point is that when it is running and when active power becomes zero and only Var is flowing out, the fuel consumption is just to cover losses in primover and...
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 Waross,
I commented to fire pump vendor that their setting protection curve is above hot stall time and as such the motor is not really protected from locked rotor condition which will cause damage to motor.
However they said that the fire pump set is approved as UL listed and as such they...
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...
Thanks dpc,
The tank is the raw and service water storage tank made from carbon steel used in power plant.
From my experience, even though the tank has handrail above, still there is no separate air terminals above the top of tank and seems to be the correct design. However since NFPA780 and...
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...
