Power Factor Correcting Equipment

Power distribution is more efficient if operated when the power factor (PF) is unity. An alternating voltage and the current causing it to flow should rise and fall in value equally and reverse direction at the same instant. When this happens, the two waves are said to be in phase and the power factor is unity (1.0). However, various inductive effects, such as idle running induction motors or transformers, can lower the power factor.

Capacitors help maintain the power factor at unity by providing a static source of leading reactive current and can be installed close to the load. This reduces the lagging current. The power factor is the ratio of actual power to the product of volts times amperes. Capacitors operate on 60-Hz sine-wave power lines at the voltage listed on the device nameplate.

The DESIGNBANK model name is used by the Work Function tool in Designer . It designates a banked feature in the network.

The PowerFactorCorrectingEquipment class (all subtypes) inherits attributes from the ElectricDevice abstract class. All model names assigned to the ElectricDevice class should be assigned to the PowerFactorCorrectingEquipment class as well.

Associations: None

Subtypes: CapacitorBank, SeriesCapacitor, ShuntReactor. The use of subtypes is optional. The Subtype attribute can be removed if subtypes aren't used in the model.

Model Names: DESIGNBANK

Attributes:

Each PowerFactorCorrectingEquipment subtype inherits attributes from ElectricDevice. In addition each subtype may also have its own attributes. The PowerFactorCorrectingEquipment subtypes are described below.

CapacitorBank

Capacitors store electrical energy and release it back into the power system when required to reduce voltage drops. CapacitorBank represents a feature that neutralizes the effect of customer inductive loads, providing capacitive reactance to balance inductive reactance loss. One bank is associated with each phase; a three-phase circuit has three capacitor banks. Banks are fixed or switched: permanently connected or automatically switched to supplement voltage rise during heavy load conditions. Delta and single phase connections are usually made on low-voltage circuits.

Associations: CapacitorUnit, CapacitorControl

Subtypes: Fixed Bank, Switched Bank

Attributes:

SeriesCapacitor

Capacitor units are placed in series to connect to higher voltage and transmission systems.

Associations: CapacitorControl

Subtypes: None

Attributes:

ShuntReactor

Shunt reactors reduce the inrush of fault current by introducing inductive reactance into a circuit to balance the effects of motor starting, to operate transformers in parallel, and to control current. Inrush current is the initial momentary surge current demand before a load resistance of impedance increases to its normal operating value.

The normal use for shunt reactors is to compensate for capacitive currents from transmission lines, cable, or shunt capacitors. The need for shunt reactors is most apparent at light load. Switched shunt capacitors are used in distribution substations or out on primary feeders to achieve full-load power factor more economically.

Associations: None

Subtypes: Concrete, Fiberglass, Porcelain

Attributes: