Creative Technology Provider
Necessity point when capacitor rated capacitance selection
In order to select a rated capacitance, below information has to be known.
These information has to be confirmed in order to operate and install safety.
1. Rated voltage and Highest voltage
: Rated voltage located capacitor installation and highest voltage during operation.
-> Over rated input voltage is bad for capacitor that need to be installed carefully
[Highest voltage less than 110%]
2. Kind of load and capacity[kW]
: Kind of load and active power[kW] located in capacitor installation.
3. Present power factor(%)
: Present power factor located in capacitor installation.
4. Target power factor(%)
: Target power factor in case of capacitor application.
5. Ambient temperature
: Ambient temperature located in capacitor installation.
-> Needed to install an enough ventilation because capacitor life makes to be short when
temperature is higher than recommendation ambient temperature.
◆ A formula of capacitor capacitance
Capacitor can be determined followed below formula.
Capacitor capacitance [kvar]
=
Load capacity[kW] x {tan(cos -1 present power factor) tan(cos -1 target power factor)}
1
=
Load capacity[kW] x
Film Capacitor Division
- 1
(present power factor)2
-1-
1
- 1
(target power factor)2
Technical Engineering Team
Creative Technology Provider
Ex) Install a capacitor at 100kw load with power factor 78% 440v 60Hz.
When target power factor is 96%, what is the need capacitor capacitance ?
Need capacitor capacitance[kvar] =
1
=
1000[kW]
1
- 1 -
x
(0.78)2
- 1
=
510[kvar]
(0.96)2
If reference of Samwha catalogues
440V 3P 60Hz 100kvar 5units are installed in parallel.
Film Capacitor Division
-2-
Technical Engineering Team