VSD (Electric Drives) & Energy Efficiency 1

[argentox]

There are a number of variable speed drive technologies out there. While some have a uniform power factor close to unity across the operational range (such as the VSIs), others go from anywhere around 0.4 to 0.8 (such as the Cyclos).

So, is any one type of electrical variable speed drive SIGNIFICANTLY more efficient than the other?

Thank you,

Eric

http://www.MarineEngineeringManagement.com

 

[argentox]

Thank you all for your comments and wise insight.
I went back to the books, reviewed your collective intelligence, and I think I have a better understanding of where I was wrong.

I have more questions on efficiency now... but I will need to hit the books for that.
I see also that cyclos need more reactive load = larger equipment, while LCI with a pf closer to unity can fit in a system with smaller equipment.

It looks like the obvious choice is an LCI or CSI...
now the question is how to maintain optimal efficiency on the LCI/Sync motor combination... but the user manuals may reveal that.

Thank you again everyone for your insight.
Sincerely.
Eric

 

[Skogsgurra]

You may be disappointed with the PF of a CSI. The power factor is, in fact, quite bad at lower speeds. But, as has already been pointed out several times, the PF is not a problem in an installation like this since the PF is high at high speeds and that's also where current is high. At lower speeds where current is low (affinity laws) the bad power factor has no negative influence.

I dug out a recording from long time ago where grid voltage and current can be seen. This is at a rather high speed, so PF is good. The typical stepped current can be a problem if you have capacitance in the grid since it starts ringing and that can (did in this case) cause PD with ozone production if transmitted to MV side of transformer.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[argentox]

Thank you again to the group that replied to the questions I had and I am grateful for your insight.

I am now investigating how to determine the efficiency of a drive over time.

Does anyone know how to check the efficiency claims of the manufacturer? ...and more so, what parameters to check if the efficiency of the system changes?

Thank you,

argentox