Hi Engineers
I have a 11/0.4kV 2500kVA trafo where I need 7 parallel single core cables to carry the current.
Ideal installation is 7 bunches of trefoil cables of equal length, installation conditions etc.
But the distance to LV swbd is only 5m and the phase sequence is opposite, so this...
Hi-
I am looking for a switchboard produced after IEC62271-200 for an 50Hz - 11kV offshore installation.
General limit for most vendors seem to be 4000A nominal and 50/125kA short-circuit.
Does anyone know a vendor with higher values on one or both parameters which has a reference list for...
Hi all,
I have an offshore installation with seven 50Hz generators (3 to 7MW) that can run in parallel on a 6kV distribution system. They are all grounded by NER. (8,2 to 17,3 ohm)
The original installed generators has a winding pitch that produces 3rd harmonic and the new installed generator...
In the offshore sector there is tradition to supply 400V sub switchboards by two transformers each able to carry the full load. Often a "2 of 3" scheme is selected where either the bus coupler or one of the feeders are normally open (NO) which will allow lower rating of the switchboard.
If the...
When calculating minimum SC value on the output side of a UPS I don't think we can use the normal IEC60909 approach.
Inverter current will be limited:
When bypass is not available the inverter alone shall supply the SC.
If SC occurs close to the UPS the impedance in the loop is low, and the...
Hi
Does anyone know where to find a simple spreadsheet that can calculate negative sequence current from a set of 3phase currents?
I am preparing a test of a Siprotec 7UM62 with a Omicron CMC256 and Siemens doesent specify how to test the function.
If I e.g. injects 1.2pu on two phases and...
Hi experts
I am working on a windfarm substation where the interfield voltage is 33kV. The WTG transformers and the export transformer is delta connected on the 33kV side.
On the substation we want to place a grounding transformer which is also used for 400V auxillary supply.
On 33kV side it is...
Hi
I am doing a motor starting study on an offshore installation supplied from two 29250kVA - 11kV -1500 rpm ABB generators. The machines are from 1997 and i dont have any data for damping factors.
What would be a typical factor in pu for that size of machine?
Best Regards
Preben Jakobsen
I have an asynchronous motor where the manufacturer has given two sets of data for the equivalent diagram:
* R1/X1 and Rm/Xm which are almost identical at locked rotor and at full speed.
* R2/X2 which are very different at locked rotor and at full speed.
In my calculation program i can only...
We have an application with an offshore wind farm substation designed with a monopile giving quite some vibrations in the structure due to wind and waves.
How vulnerable will an e.g. 250MW 33/150kV 50Hz transformer be for such vibrations?
More steel means less requirements to transformer vendor...
