ETP 2260C Week #1 Protective Relay 1 (E/M Relay basics this semester) Objectives this semester in ETP 2260C Protective Relay 1: Upon completion of this semester’s material, the student will be able to discern the following… 1. Describe the purpose of relays, especially protective relays. 2. Understand the difference between the “Art” and the “Science” of protective relaying in general. 3. Describe the operational understanding and theory as to how a E/M protective relay operates and functions. 4. Understand how E/M relays are applied in the power system. 5. Learn and become proficient in various electrical formula’s.

ETP 2260C Week #1 Protective Relay 1 (E/M Relay basics this week) This week we will cover the following topics in class: What is a “protective relay”, and just what does it do? Discuss the 5 basic classes of relays. (Class is a broad description) Discuss the 4 different groups of relay construction. (Group is smaller than classes of relays) Discuss the 5 different types of relay “elements”. (relay elements are specific) Discuss E/M Relays “electrical safety”, “history”, and the “basics”. Discuss the terms Art and Science of protective relaying, and what it means. Discuss basic relay applications such as: Distribution feeder, Transmission Line, Bus, Transformer, Generator, Capacitor / Inductor bank, protection and control relays.

ETP 2260C Week #1 Safety pre-job briefing. We will begin with safety and end with safety. (Electrical safety). Today we will discuss two types of protection…System Protection and Personal Protection. System Protection focuses on protective relays, fault currents, effective grounding, circuit breakers, transformers, switches, and more. Personal Protection focuses on P.P.E., Safety equipment, rubber gloves, insulating blankets, grounding jumpers, switching platforms, switching and tagging or lockout / tagout, and so forth. This week and next, we will focus on System Protection and the art and science of protective relaying.

ETP 2260C Week #1 Protective Relay 1 (Text book ref.) This course will refer to the following text book, chapter and page #. Power Line Worker: Substation, level 3 trainee guide. Please study and review over the course of the next 16 weeks, Module #7, System Protection and Control. In this module #7, please read and review pages There will also be an instructor prepared custom Power Point each week that will compliment this text book. Thanks, Bob Seigworth.

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics) The NERC North American Electric Reliability Council describes electric utility relay protection systems as the following definitions: Electrical system protective relays, associated communication systems, voltage and current sensing devices, station DC battery systems, and DC voltage control circuitry. These electrical system protection and control devices are normally found in generating plants, transmission and distribution substations, and industrial and commercial load cednters.

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics) What is a protective relay, what does it do, and why? A protective relay is a device that recognizes an electrical system abnormality such as a short circuit or electrical fault, and isolates that fault through the operation of a HV power circuit breaker protecting the electrical source or load. Protective relaying is one of several features of electrical system design concerned with minimizing the damage to equipment and interruptions to the “B.E.S.” Bulk Electric System when electrical failures or abnormalities occur. When the word “protective” is used, it conveys that, together with other equipment, protective relays help to minimize damage and improve B.E.S. reliability and service!

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics) The Art and Science of Protective Relaying explained. (2 parts) Part one is the “Art” of protective relaying, and involves the way in which you apply the scientific principles of relay work as a whole. An example of the “Art” side would be to use the analogy of making sure just enough of the electrical system is isolated (equipment isolation) when a problem occurs, but leave enough of the electrical system intact for customer reliability, but still protect the B.E.S. (This correlates to safety!) Part two is the obvious “Science” of protective relaying. This involves the physical and mathematical aspects of protective relaying such as volts, amps, and phase angle with regard to the actual physical make up of the relay. In summary, how the relay responds to voltage, current, and the phase angle between the two electrical components.

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics) The five classifications of relays. (not to be confused with relay elements) 1. Auxiliary relay 2. Regulating relay 3. Monitoring or verification relay 4. Programming relay 5. Protective relay

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics) Relays come in many different sizes, shapes, and designs, but basically there are four groups of relay construction. The four groups are: 1. Electromagnetic attraction relays (plunger and clapper) 2. Electromagnetic induction relays (induction disk and induction cup) 3. Thermal induction relays 4. Electro-mechanical / solid state / numerical impedance relays.

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics) Relays come in many different sizes, shapes, and designs, but basically there are five types of relay construction or “Relay Elements”. The five types are: 1. Plunger type 2. Clapper type 3. Induction disk type 4. Induction cup type 5. Solid state and numerical types.

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics) E/M Relay Theory and Measuring Principles. (Induction disk or cup) The E/M protective relay converts the voltage and current flowing within the relay itself to a “magnetic and electrical force” that produces a rotational torque on an axis which has a moving contact affixed to it, operating by electrical attraction. There is also a restraint spring associated with the moving contact and its rotating axis that constantly applies a force to keep the axis from moving. This torque the relay develops electrically must overcome the restraint spring allowing the moving contact to strike the stationary contact.

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics) E/M Relay Theory and Measuring Principles. (electrical attraction relay) The E/M Electromagnetic attraction relays generate a magnetic force of attraction through electrical current flowing through a coil of wire that has a moving armature or solenoid that is acted upon by the field of flux surrounding the coil of wire. If there is sufficient current flowing in the heavy coil of wire, the armature or solenoid plunger will move causing the moving contacts to strike the stationary contacts therefore acting like a switch contact conducting electrical current.

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics) Protective relays are constructed, designed, and built so they will respond to the following electrical abnormalities… 1. Faults in a specified section of a circuit (Percentage differential relays). 2. Changes in current flow or magnitude (Over-current relays). 3. Fluctuations in applied voltage (Over / Under voltage relays). 4. Frequency fluctuation or changes (Over / Under-frequency relays). 5. Changes in thermal temperature (Over temperature relays)

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics) This semester we will cover the following E/M relay basics. 1. History 2. Theory 3. Application 4. Design (Electrical and mechanical design) 5. Relay Settings development and use 6. Protective relay maintenance, testing, trouble shooting. 7. Commissioning

ETP 2260C Week #1 Protective Relay 1 (Specific relay protection scheme Examples) 1. Distribution Feeder protection is typically Over-current protection. 2. Transmission line protection is step-distance / impedance, or line differential protection. 3. Substation electrical bus protection is typically differential protection. 4. Power transformer protection is typically differential protection. 5. Generator protection is typically a combination of protection schemes including differential, over-current, and O.V. / U.V. 6. Capacitor and Inductors bank protection is typically over-current protection.

ETP 2260C Week #1 Protective Relay 1 (T-line relay protection scheme example)

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics) The following slides are examples of E/M or “Electro-Mechanical” relays. General Electric E/M (Miscellaneous functions) Westinghouse E/M (Miscellaneous functions)

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics, early model G.E. A/C O.C.) 1925 G.E. model #AC, overcurrent relay

ETP 2260C Week #1 Protective Relay 1 (Protective Relay Basics, 1937 early model WH-CO)

ETP 2260 Week #1 E/M protective relay types and manufactures. G.E. E/M IAC over-current relay

ETP 2260 Week #1 E/M protective relay types and manufactures. Westinghouse E/M CO over-current relay

ETP 2260 Week #1 E/M protective relay types and manufactures. (G.E. PJC plunger style O.C. Relay)

ETP 2260 Week #1 E/M protective relay types and manufactures. G.E. E/M IAV voltage relayWestinghouse COV 8 voltage relay

ETP 2260 Week #1 E/M protective relay types and manufactures. Agastat “Bellows type” Timing relayWestinghouse 1936 TK timing relay

ETP 2260 Week #1 E/M protective relay types and manufactures. General Electric GCY distance relayWestinghouse KD-4 distance relay

ETP 2260 Week #1 E/M protective relay types and manufactures. General Electric BDD transformer DiffWestinghouse HU Transformer Diff

ETP 2260C Week #1 Protective relay 1 Close this weeks lesson with safety. Use caution when working around any equipment that is energized and in-service. Prior to starting maintenance, construction, or trouble shooting, make sure that the equipment you are working on is in a safe mode, and de-energized if at all possible. Make sure that you follow work methods and procedures, and certainly all safety guidelines.