Soft Starter Voltage Drop

[nhcf]

A very basic question on effect of a RVSS on upstream power distribution.

If an across-the-line starter draws 600% FLC, resulting in a voltage drop of 5% on upstream distribution - if we use RVSS and limit start current to 400% - does this mean voltage drop is reduced by 1/3?

I am trying to understand the impact of the RVSS operating at reduced voltage and reduced current - so the actual KVA output from the starter is reduced by more than 1/3. What is the impact on the upstream distribution? I assume upstream distribution sees the full 400% current.

 

[LionelHutz]

Yes, the new voltage drop would be roughly 3.3%. The RVSS operation is a bit of an enigma in that it really just reduces the current.

 

[itsmoked]

Lionel did you mean 33%?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[nhcf]

In my example, I think he meant that 5% voltage drop would be reduced to 2/3 of 5%, or 3.3%.

 

[itsmoked]

AH! Thanks for that nhcf.

Keith Cress
kcress -

http://www.flaminsystems.com