Hello,
We have a 150HP DC motor where the interpoles after overhaul were connected with wrong polarity. Half an hour after start the motor drive tripped and the amature suffered catastrophic overheating in the area just after the commutator, I believe it is where the windings are being...
Hello,
For test and educational purpose I need a small 3-phase AC synchronous generator.
The generator shall have rotor windings with slip rings/brushes for excitation control.
Exact size does not matter, could be a few hundred watts or less.
Have any seen such a kit around or perhaps a...
Hi,
Wonder if one of you guys have been facing similar "problems":
I am modeling automatic voltage regulators and excitation systems for smaller synchronous machines. Size is typical 3-10MW, and the machines are 10-15 years old.
One of my main problems is how to derive the parameters for the...
Dear friends,
We have a transformer, 3000kVA - step-down 6kV/0.4kV - cast resin - insulation class F.
Right now it is running at winding temp 130 deg. cel. (full load - PT100 embedded measurement). Ambient temperature is 20 deg. cel.
Ambient temperature is expected to reach approx. 35.
We...
Hi (again),
We are installing a 150kW induction motor, for a lifting device. Motor has to start on full load torque.
The terminal voltage must not drop too much during start, to ensure enough torque. My problem is how to calculate max. voltage drop. Voltage drop will of course depend on...
Hi,
We have an impressed current cathodic protection of a steel structure in seawater.
I found that the main electrical resistance exists in the vicinity of the anode. Driving voltage is +50 V at anode, cathode voltage is 0 V.
Can anyone give a hint how to model an circular anode in FE software...
Hi,
Could anyone tell why a 3-phase power transformer shows a so nonlinear and high inrush current characteristica, when induction motors do not.
Of course induction motors do have a high (4-8 x In)starting current, but it seems low compared to transformer inrush of 10-20 x In.
The electric...
Hi,
have anyone worked with IEC 34-14, dealing with subj.??
If so you may be able to answer me: why do it state that vibration severity should be measure at NO LOAD, when I just now realize that f.x. rotor winding interturn shorts can easily be detected as high vibrations at loaded condition...
Hello,
We have a cable installation (separate conductors) feeding a VFD - 5.5 MVA. Converter is "6-pulse" type.
The feeding cables will run 98% full load (24-7), and we are not sure if the cable capacity should be upgraded due to the harmonics. Right now we have not the exact numbers for THD and...
Hi fellows
,
You helped me before, here I go again ;-)
Need to calculate/simulate how much voltage harmonics, a motor drive introduce in rest of supply system.
The motordrive is placed near the supplying generator.
Should I use the generator synchronous reactance or subtransient reactance as...
Hi,
I have a small portable powergenerator:
350kVA, 280kW, 400V, 505A, 50Hz, PF=0,8 and 1500 rpm.
From data sheet
xd''=0.140 pu, saturated
x2 =0.140 pu (neg. seq.)
My question is now this x2, is it subtransient or what?
Can I use x2 (and xo, zero. seq.) for synchrounous generators for short...
Hello,
I have made an induction machine model in Simulink using qd0-transformation theory. I would like to test the performance of the model by comparing model output with "real" test data. Therefore i am looking for time vs current and time vs speed data for real motors (of course together...
Hello,
I have a 3500 kVA/6.6kV salient pole synchronous generator. The system is not grounded (isolated).
My simulations, in SimPowerSystem, show that the 2 phase sc, on main busbar (steady-state) is larger than the 3 phase sc. Is this correct ? If correct, then how can I calculate the 2 phase...
