11kv motor vs 3.3 kv motor in a 33 kv system
11kv motor vs 3.3 kv motor in a 33 kv system
(OP)
hi all,
I would like to know your views on this subjcet which will be a better option with the incomming supply to the plant is 33 kv moderately stable voltage
thanks in advance
7465
I would like to know your views on this subjcet which will be a better option with the incomming supply to the plant is 33 kv moderately stable voltage
thanks in advance
7465





RE: 11kv motor vs 3.3 kv motor in a 33 kv system
How large is the motor?
How firm is the supply?
Dedicated transformer or added to a partially loaded transformer?
Starting method?
What is the nature of the load?
respectfully
RE: 11kv motor vs 3.3 kv motor in a 33 kv system
11kV switchgear and cabling is more expensive and requires a different set of skills to install and maintain it compared to a 3.3kV installation. 3.3kV cabling is little different to LV cable in construction except the XLPE is thicker; 11kV cable is much more complex in construction and requires purpose-made terminations and joints which in turn need an increasingly rare set of skills to install correctly. Maybe this isn't an issue if there is already 33kV gear on site.
If you need to feed the motor from a remote substation then 11kV will allow you to use cheaper and reasonably sized cable whereas 3.3kV would require multiple conductors. Cable cost is getting increasingly significant - burying copper in the ground is an expensive proposition these days - so if the installation requires a long cable run to the motor the 11kV cable will likely have a lower installed cost than the 3.3kV cable.
11kV equipment will almost certainly see PD activity at some level. 3.3kV gear essentially does not suffer from PD. You would be prudent to consider PD monitoring if this is an important installation.
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Sometimes I only open my mouth to swap feet...
RE: 11kv motor vs 3.3 kv motor in a 33 kv system
7465
RE: 11kv motor vs 3.3 kv motor in a 33 kv system
Have you considered using (say) 690V for this drive? LV soft starters are available in this size range - you open up a lot more possibilities for the switchgear, at the expense of an unusual motor and some very heavy conductors. You will need to keep the LV substation and soft start close to the drive.
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Sometimes I only open my mouth to swap feet...