High Voltage Capacitors for Power Factor Improvement
High Voltage Capacitors for Power Factor Improvement
(OP)
I need to improve the power factor of a steel induction melting furnace plant from 0.95 to 0.99. The total kW load is 1700 kW ( out of which 1500 kW is the furnace load ).
The furnace is fed through a 11kv/550V,1750 KVA Trafo and rest of the auxillary load ( pumps, cranes, lights )is fed through a 11kv/415V,250 KVA Trafo. What is the optimum point to install power factor improvement capacitors ? I am in favour of 11 kV capacitors.
The furnace is fed through a 11kv/550V,1750 KVA Trafo and rest of the auxillary load ( pumps, cranes, lights )is fed through a 11kv/415V,250 KVA Trafo. What is the optimum point to install power factor improvement capacitors ? I am in favour of 11 kV capacitors.






RE: High Voltage Capacitors for Power Factor Improvement
RE: High Voltage Capacitors for Power Factor Improvement
I might add some obvious comments. If you add the capacitors at the 11kv bus, then there is no reduction in load (and losses) through the 550 and 415v transformers and associated cables. By adding the caps at the lower voltage buses, you slightly reduce load on the transformers...5% reduction in current if you go from 0.95 to 1.0 pf... This equates to roughly 10% reduction in temperature rise and possibly may increase the life/reliability of your transfomrers. Also you'll reduce the I^2*R losses in your transformers by approx 10% (but it's probably a fairly small number to begin with).
I'm sure there are lots of other cost/complexity factors in the decision.
RE: High Voltage Capacitors for Power Factor Improvement
RE: High Voltage Capacitors for Power Factor Improvement
RE: High Voltage Capacitors for Power Factor Improvement
I really don't have much insight into other cost/complexity/reliability differences between the two options. (I'm sure there's others out there that can provide more info)
RE: High Voltage Capacitors for Power Factor Improvement
the best way is to install capacitors with properly de-tuned reactors somewhere else, not on furnace transformer. since i am doing this activity on commercial basis and installed about 20 such equipment rest detials, will be furnished if you can please contact me on ambikharmonic@vsnl.com
RE: High Voltage Capacitors for Power Factor Improvement
RE: High Voltage Capacitors for Power Factor Improvement
POWER FACTOR FROM 0.95 TO 0.99 FOR 1700 KW LOAD. @ 242.23 KVAR REQUIRED FOR .99 PF FOR 1700 KW. MY SUGGESTION IS FOR HIGH VOLTAGE CAPACITOR BANK TO FIX CAPACITOR & TRY INSTALLED ON LT SIDE BECAUSE FURNACE ACTIVE & REACTIVE LOAD ALWAYS FLUCTUATE DUE TO THAT RESULTANT PF ALSO FLUCTUTATE.HIGH VOLTAGE CAPCITOR BREAKER RATING 2 TIMES OF NORMAL VOLTAGE (AROUND 22 KV) DUE TO SWITCHING OF CAPCITOR . i.e COST ALSO INCRESED.
RE: High Voltage Capacitors for Power Factor Improvement
CONTINUES CHANGE WITH FURNACE LOAD.
RE: High Voltage Capacitors for Power Factor Improvement
RE: High Voltage Capacitors for Power Factor Improvement
PFtotal=PFfundamendal/[1 + (THDi in %/100%)**2]**0.5
where
PFtotal is total power factor where current harmonics appears
PFfundamental is your normal 60Hz or 50Hz power factor, normally used if the harmonics are not considered or present
THDi is the current total harmonic distortion (see IEEE Std 519, or IEC counterpart)
which means that your current power factor is lower due to harmonic contamination, if applicable.