Which device is used to improve power factor in a substation system?

• A. Capacitor
• B. Fuse
• C. Router
• D. Transformer

Answer: (A)

Capacitors are used to improve power factor in substation systems. Power factor measures how effectively real power is turned into useful work; inductive loads such as motors and transformers draw reactive power, which lowers the power factor and increases the current for a given real power. A capacitor provides leading reactive power, offsetting the inductive reactive power and reducing the net reactive power. When capacitor banks are connected in parallel to the bus (shunt), they correct the PF and can also help with voltage stability and reducing losses by lowering current. The other options don’t serve this purpose: fuses protect circuits, routers handle data networking, and a transformer changes voltage but isn’t used primarily to correct power factor (its magnetizing current can affect PF only incidentally).