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File Magic Plus-000011Bf.Mag FOREWORD The level of voltage maintained at a consumer’s service entrance is one of the most important indicators of the quality of electric service which is being provided. The consumer is entitled, at all times, to a level of service voltage which will make it possible for equipment re- ceiving power from the system to operate effectively and efficiently. The voltage levels recommended by REA are given in Bulletin 169-4, "Voltage Levels on Rural Distribution Systems." These levels are based on American National Standard c84.l-l970, "Voltage Ratings for Electric Power Systems and Equipment (60 Hertz)." Both voltage regulators and shunt capacitors have a place in voltage control for a distribution system. Capacitors are more efficient in correcting chronically low voltage, especially where this can be realized as a side benefit to the capacitor's principal function of improving power factor. Voltage regulators provide a more effective correction of voltage swing caused by fluctuations in load or in the supply voltage. You should study not only this Bulletin (169-27) but also Bulletin l69-l, "The Application of Shunt Capacitors to the Rural Electric System" in evaluating the proper application of these devices to best suit your needs. Bulletin 169-27 ontents I. INTRODUCTION ................................Table................................ of C ......................................................1 II. VOLTAGE SPREADS AND VOLTAGE DROPS ...................................................................1 A. ANSI .....................................................................................................................................1 B. REA Recommendations on Voltage Levels .........................................................................2 III. VOLTAGE REGULATIONS ....................................................................................................3 A. Types ....................................................................................................................................3 1. Induction-Voltage Regulator ..........................................................................................3 2. Step-Voltage Regulator ..................................................................................................4 B. General Description ..............................................................................................................6 1. KVA Ratings ..................................................................................................................6 a. Extended Range of Ratings ......................................................................................6 2. Terminal Designations ...................................................................................................7 3. Regulator Standards .......................................................................................................7 a. Short Circuit Strength ..............................................................................................8 C. Regulator Controls ................................................................................................................9 1. General ............................................................................................................................9 a. Voltage Level .........................................................................................................10 b. Bandwidth ...............................................................................................................10 c. Time Delay .............................................................................................................11 d. Range of Regulation ...............................................................................................11 e. Line Drop Compensator .........................................................................................11 2. Control System Accuracy .............................................................................................14 D. Single-Phase Versus Three-Phase ......................................................................................14 IV. THE REGULATOR AND SYSTEM VOLTAGE LEVELS ...................................................15 A. System Voltage Profiles ......................................................................................................15 1. Effects of Line Drop Compensation ..............................................................................16 B. Regulator and System Voltage Savings ..............................................................................19 C. The Role of the Line Regulator ...........................................................................................20 V. APPLICATION .........................................................................................................................22 A. When is a Regulator Required? ...........................................................................................22 B. Where to Install the Regulator? ...........................................................................................23 1. Location Considerations ..............................................................................................23 C. Regulator Settings ...............................................................................................................23 1. Voltage Level ...............................................................................................................24 2. Bandwidth ....................................................................................................................24 3. Time Delay...................................................................................................................25 a. Substation ...............................................................................................................25 b. Line Regulators ......................................................................................................26 c. Controlling Regulator Operations ..........................................................................26 Bulletin 169-27 Contents (Continued) 4. Range of Regulation ....................................................................................................27 a. Setting the Range ...................................................................................................27 b. Selecting the Regulator Size ..................................................................................28 c. Shifting the Range of Regulation to Increase Substation Loading ............................................................................................28 5. The Line Drop Compensator .......................................................................................29 a. General ...................................................................................................................29 b. What Does the LDC Do? .......................................................................................29 c. Setting the LDC .....................................................................................................31 d. Special Considerations ...........................................................................................33 D. Lightning Protection ............................................................................................................34 E. Reversibility……………………………………………………………....……………….34 UNITED STATES DEPARTMENT OF AGRICULTURE Rural Electrification Administration January 1973 Supersedes March 1954 REA BULLETIN 169-27 SUBJECT: Voltage Regulator Application on Rural Distribution Systems I. Introduction: Demands on an electric distribution system today are such that voltage levels throughout the system must be held within certain prescribed limits. Consumers will no longer tolerate wide voltage variations at the point of service anymore than they will tolerate service interruptions. Consumers are demanding and are entitled to high quality electric service. The use of voltage regulators has long been recognized as a primary means of maintaining system voltage levels, but regulators are often not used to their full capability. It is the purpose of this bulletin to explore the application of voltage regulating devices so that the maximum benefits from sound voltage regulator application can be achieved. II. Voltage Spreads and Voltage Drops: In many states the limits of voltage spread permitted at the consumer's meter are fixed by the state regulatory commission. In states where borrowers are not subject to such controls REA recommends the limits established by the American National Standards Institute. A. American National Standard Institute (ANSI) Voltage Limits The revised American National Standard, C84.l-1970, ''Voltage Ratings for Electric Power Systems and Equipment (60 Hertz)," approved January 1970, establishes the voltage limits shown in Table 1. MINIMUN MAXIMUM RANGE Utilization Voltage Service Utilization & Non-lightning Loads includ- Voltage service voltage loads ing lighting A 108 110 114 126 B 104 106 110 127 Table l. Voltage Ranges (120 Volt Base) Bulletin 169-27 Page 2 o Range A defines the limits within which service voltages should be held. o Range B defines the limits that service voltages may vary from the limits of Range A for limited durations due to system design or operation. B. REA Recommendations on Voltage Levels REA Bulletin 169-4, ''Voltage Levels on
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