power systems loss

BULLETIN 1724D-112: APPLICATION OF CAPACITORS ON RURAL ELECTRIC SYSTEMS How power factor affect the systems loss in distribution system?                                   UNITED STATES DEPARTMENT OF AGRICULTURE                                                                  Rural Utilities Service                                                               BULLETIN 1724D-112 SUBJECT: The Application of Capacitors on Rural Electric Systems. TO: RUS Electric Borrowers and RUS Electric Staff EFFECTIVE DATE: Date of Approval OFFICE OF PRIMARY INTEREST: Distribution Branch, Electric Staff Division AVAILABILITY: This bulletin is available on the Rural Utilities Service website at http://www/ .usda. gov/rus/electric. INSTRUCTIONS: Replaces rescinded Bulletin 169- 1 PURPOSE: To provide Rural Utilities Service (RUS) borrowers and others guidance on the use, characteristics, and benefits of power factor correction capacitors on rural distribution systems. To view the

Which is better for voltage regulation, capacitor ot voltage regulator? One of the greatest advantages gained by the proper sizing and location of distribution capacitors is voltage improvement. By placing leading volt-amperes reactive (VAR) loads (capacitors) near lagging VAR load centers (motors for example), the lagging VARs on a system basis are cancelled with an associated increase in voltage.

What is the difference between substation capacitor and line capacitors? If capacitors are installed primarily to reduce or eliminate bulk power charges for kVAR or for other reasons associated with wholesale purchased power such as contractual requirements, they can be installed in substations to supplement distribution line installations. Installed equipment cost for substation capacitors may be less than that for the same amount of line kVAR because the substation units can package many kVAR in a single installation and can be switched with a single three-phase switching device and control unit. However, the distributor does not get the benefit of reduced distribution line losses by installing capacitors at substations, so such installations should be made only after the maximum practical amount of line capacitors has been installed.

CAPACITOR OPERATION AND MAINTENANCE Basic operation and maintenance of capacitor in distribution system Capacitors on distribution lines must be kept operational if their benefits are to be retained. Lightning surges or other disturbances occasionally cause capacitor fused cut-outs to open, and the distributor should promptly check and refuse such units to keep all capacitors operational. Care should always be taken in refusing capacitor units, since energizing units that have been damaged internally often results in capacitor case failure. Since no consumer complains when a capacitor cut-out opens, some distributors might delay returning the capacitor to service. However, such delays are costly to the distributor because of increased line losses and possible wholesale power factor surcharges. Switched capacitors need to be checked periodically to ensure proper operation of switches and controls. Operation counts should also be recorded. A large or small number of operations may i

CAPACITOR PLACEMENT AND CAPACITOR & VOLTAGE REGULATORS How does capacitor and regulators affect each other during operation? The installation of capacitors on a feeder can interfere with the proper operation of voltage regulators on that same feeder. This problem is relatively simple to overcome, but should not be ignored. Even fixed capacitors can cause some interference with regulators, but the interference is greater with switched capacitors. Capacitors, either fixed or switched, installed on the upstream side of the load center of a voltage regulator’s line drop compensator setting can thwart the compensator’s reactance setting. This problem is easily solved by setting the reactance compensation to zero and increasing the resistance compensation enough to achieve the same results previously obtained with both types of compensation. A voltage controlled switched capacitor on the load side of a voltage regulator can fail to switch properly because of action being taken by

TYPES OF SWITCHED CAPACITOR CONTROLS PART 2 What are the different types of switched capacitor control? In continuation of the types of switched capacitors control, we have include some intrinsic characteristics of the power system as the basis for capacitor switching which includes;  voltage, current, kvar, power factor, and combination of some of mentioned capacitor controls. Voltage Control A voltage control switches a capacitor on when line primary voltage is low, and switches the capacitor off when the voltage is high. The advantages of a voltage control include: (1) Primary line voltage is often closely related with line load and power factor, so the control responds to actual conditions; (2) Line voltage is an important index of the overall quality and efficiency of the feeder, so the control responds to a critical line condition; (3) It is simple to install, set, test and maintain; and (4) Although it requires a voltage signal, it does not require a line curre

TYPES OF SWITCHED CAPACITOR CONTROLS PART 1 What are the different types of switched capacitor control? There are many methods of automatic control of switched capacitors. The On and Off switching controls can be achieved by a time clock, an ambient temperature sensor, a line voltage-sensing device, a line current-sensing device, a power factor sensor, line kVAR flow sensing or other means such as a remote control. Different types of capacitor controls can be used for various installations on the same feeder, and combination control schemes can be used even on a single installation. The following is a summary of the advantages and disadvantages of various capacitor control methods. Time-Clock Control A time-clock control switches a capacitor on for those hours of the day when load is expected to be the highest, and switches the capacitor off for expected light-load hours. Controls are available that automatically change the on-off schedule during weekends or even seas