Hello !
Please help me with the equations to calculate the starting time of a WRIM motor, started with an LRS.
Data known:
-Motor voltage rating;
-Shaft power output;
-Motor rotor inertia;
-Load inertia;
-In = I1 at full speed @ full load;
-Locked rotor torque: 260% Tn
-I2 and V2;
-synchronous...
Hello!
It is possible to build a power transformer with these parameters:
S=250 MVA
V=500 / 30 kV
Vector group: Preferably YNd
?
What is the maximum transformation ratio a power transformer could have?
Thank you in advance!
Regards,
Stefan
Hello!
I am working on a feasibility study, where I have to define a concept design and estimate de cost of the project.
In this project, the process plant load will be supplied through a transmission line from a hydro power plant. The transmission line should be double circuit, each circuit...
Hello!
I have to design an island power plant, maximum 45 MW, with a relatively high fluctuating load. Say continuously maximum 30 MW. The only fuel available is diesel.
I am proposing a plant configuration based on 6 x 7.4 MW (N+1) = 37 MW medium speed diesel generators and 6 x 1.6 MW (N+1) =...
Hello!
I am looking for advice regarding lightning protection of a tower crane.
I have a tower crane, 55 m high. It is the highest structure on a few km around. The crane’s structure is connected at the base to the plant earthing grid (< 1 Ohms).
The Client wants to have an lightning rod...
Hi !
I am writing this tread to kindly request your opinions.
I came across a Client technical specification for low voltage induction motors that states:
“Motors shall be able to start under applicable load conditions with 75 % of rated voltage at motor terminals for DOL.”
I believe that...
Hello !
I would appreciate any opinions on this topic.
Recently I had an argument with one colleague, regarding the grounding of MV generators in a small power plant.
There will be 3 gas generators, 3 MW 13.8 kV, windings start connected.
We agreed that an acceptable technical and cheap...
Hi all !
I have to review a tender bid submission for a 34.5 kV, 14 MVAr power factor correction capacitor bank, equipped with a shunt reactor tuned to 5th harmonic.
The 3 Ph symmetrical SC in the PCC is aprox. 20 kA/1sec.
The unit is comprised from a capacitor bank (spited unearthed star) in...
Hello!
I would like to have an advice on how to configure a capacitor bank, for power factor correction application.
The networks voltage is 6.6 kV.
Doing the maths, to improve the PF from 0.8 to 0.95, it requires almost 1.2 MVAr, lets say I need a capacitor bank able to deliver Q = 1.2 MVAr...
Why unearthed power generation & distribution system (say 440 V AC/60Hz) is preferred on ships, rather than earthed power system (common neutral bar).
The only advantage of an unearthed system I know is that offers good continuity in operation.
On the other hand, it requires a higher insulation...
Hi!
I have to calculate the voltage drop in case of DOL starting a 6.6 kV induction motor (squirrel cage).
I used starting PF=0.3.
My boss said that PF=0.3 is too low for a MV motor.
I recall a calculation example from an IEEE book, that use for a LV motor, the starting PF=0.2. Therefore, I...
