- Switchable Capacitor Bank Definition: A switchable capacitor bank is defined as a set of capacitors that can be turned on or off to manage reactive power in an electrical system.
- Purpose: The main purpose of a switched capacitor bank is to improve power factor and voltage profile by balancing the inductive reactive power in the system.
- Reactive Power Management: Switched capacitor banks help in reducing overall reactive power, which enhances system efficiency and stability.
- Automatic Control: These banks can be controlled automatically based on system voltage, current load, reactive power demand, power factor, or timers.
- Benefits: Using switched capacitor banks can improve the power factor, stabilize voltage, and enhance overall system performance.
A switched capacitor bank can be taken in or out so the Capacitor vars track the inductor vars of the load. That cuts net reactive power, which raises power factor and supports the voltage profile. A bank left in when the inductive load is light can push the system toward a leading power factor.
It is not always worth leaving a capacitor bank connected. The Capacitor supplies vars that oppose the inductive load. When that load is already small, the power factor is already high and extra capacitive vars make it worse.
A switchable or switched capacitor bank is the usual choice when the inductive load varies. These banks sit in the primary network of a substation and help the voltage and var profile of the transformers and feeders.
The bank can switch on and off from system quantities:
- Voltage control: the system voltage falls as load rises, so the capacitor can switch on below a set voltage and switch off above a higher set voltage.
- A Capacitor bank can also switch on and off from the ampere loading of the circuit.
- The bank offsets reactive power, measured in kvar or MVAR. It switches on when kvar demand rises above a set value and switches off when demand falls below another set value.
- Power factor can also control a capacitor bank. When system power factor falls below a set value the bank switches on.
- A timer can also control the bank, for example switching it off at the end of a factory shift.
