LV Capacitor Banks Automatic Power Factor Correction Panels

Mar 20,2021

A capacitor bank is a grouping of several identical capacitors interconnected in parallel or in series with one another. These groups of capacitors are typically used to correct or counteract undesirable characteristics, such as power factor lag or phase shifts inherent in alternating current (AC) electrical power supplies.

FEATURES:

Power factor correction by multi step design
Standard & detuned capacitor banks(with Reactors)
Capacitor units are metal encapsulated of temp Class D
Capacitors are Self-healing, pressure sensitive disconnections with discharge resistors
Microprocessor based power factor controller with various switching sequences
Special Contactors for power factor correction capacitors; equipped with limiting resistance for the inrush current
Easy installation & maintenance

An additional benefit of doing these calculations in a spreadsheet is that other calculations of interest can be incorporated. Such calculations might include no-load voltage rise with fixed capacitors and the resonant harmonic frequency of the system when capacitors are added (if the user inputs certain system information, including source transformer kVA and percent impedance).

TABLE 1

EXAMPLE POWER FACTOR CALCULATIONS,

USING MONTHLY DATA, .95 PF TARGET

TABLE 2

EXAMPLE POWER FACTOR CALCULATIONS,

USING SUMMARIZED DATA, .95 PF TARGET

Sometimes a power factor penalty is somewhat hidden. For example, in a straight kVA demand rate there is nothing that explicitly mentions a power factor penalty. But a poor power factor will result in a higher kVA for a given kW of load, so there is an implicit power factor penalty built into that rate. In other cases the utility may give a rebate for maintaining a power factor above a given level. At a glance you might not think you are paying a penalty if you do not get this rebate. But you would be leaving money on the table if you did not take advantage of the rebate. It is functionally equivalent to a power factor penalty, just phrased differently.

Users should be aware that capacitor over-voltage capability was not intended for everyday use but rather for contingency use. If the motors are switched daily, or harmonics or transients are present, or the capacitors occasionally are on line without load and the feeder voltage rises, the life of the capacitor will be shortened. Operations personnel should strive to minimize such motor starts to maximize capacitor life.