power systems loss

CAPACITOR FUSING APPLICATION GUIDE RULES Basic points to consider in fusing a capacitor in electric system network 1) Purpose of fusing:                 a. to isolate faulted bank from system                 b. to protect against bursting                 c. to give indication                 d. to allow manual switching (fuse control)                 e. to isolate faulted capacitor from bank 2) Recommended rating:                                a. The continuous-current capability of the fuse should be at least 165 percent of the normal capacitor-bank (for delta and floating wye banks the factor may be reduced to 150 percent if necessary).                 b. The total clearing characteristics of the fuse link must be coordinated with the capacitor "case bursting" curves. 3)  Tests have shown that expulsion fuse links will not satisfactorily protect  against violent rupture where the fault current through the capacitor is greater than 5000 amperes. 4)  The c

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 INSTRUCTIONS: Replaces rescinded Bulletin 169- 1 PURPOSE: To provide Rural Utilities Service (RUS) borrowers and others guidance on the use, characteristics, and benefits of power factor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

TYPES OF CAPACITOR INSTALLATIONS What are the types of Capacitor Installation known? Capacitors are relatively easy to install and are among the most trouble-free electrical devices. Line capacitor installations are protected with conventional cut-out fused switches, and capacitor failure is rare if the appropriate fuse element is used. (Fuse rating should be closely coordinated with capacitor size.) There are several types of capacitors (see figure below). Following Load Reactive Power The most difficult aspect of capacitor application is the maintenance of proper balance between total kVAR of capacitors connected at any particular time and load kVAR present at that time. Like load kW, load kVAR changes over time, so some provision must be made to vary the total connected capacitive kVAR to roughly follow the load kVAR. Installing capacitors based on the peak load kVAR and leaving all these capacitors connected at off-peak times is strictly inadvisable, since excessive capaciti

CAPACITORS FOR POWER DISTRIBUTIONS SYSTEM How does Capacitors installed in the power distribution system affect the operation? The basic definition of a capacitor would be that it is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric (insulator). Capacitors are used as parts of electrical systems, for example, consist of metal foils separated by a layer of insulating film. When there is a potential difference (voltage) across the conductors, a static electric field develops across the dielectric, causing positive charge to collect on one plate and negative charge on the other plate. Energy is stored in the electrostatic field. An ideal capacitor is characterized by a single constant value, capacitance, measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them. Th

SHUNT CAPACITOR BANK FUNDAMENTALS AND PROTECTION TECHNICAL PAPER Technical Paper written by: Gustavo Brunello, M.Eng, P.Eng, Dr. Bogdan Kasztenny, Craig Wester ABSTRACT Shunt capacitor banks are used to improve the quality of the electrical supply and the efficient operation of the power system. Studies show that a flat voltage profile on the system can significantly reduce line losses. Shunt capacitor banks are relatively inexpensive and can be easily installed anywhere on the network.   This paper reviews principles of shunt capacitor bank design for substation installation and basic protection techniques.  The protection of shunt capacitor bank includes: a) protection against internal bank faults and faults that occur inside the capacitor unit; and, b) protection of the bank against system disturbances.Section 2 of the paper describes the capacitor unit and how they are connected for different bank configurations. Section 3 discusses bank designs and grounding connections.