Protective relaying for power generation systems free download

A thyrite lightning arrester has a combination of inverse resistance characteristics and gap Thyrite arrester is most common and is mostly used for the protection against high dangerous voltages The manufacturing processes have been perfected so that the electrical and mechanical characteristics can be duplicated or varied as desired within practical limits It does not follow Ohm's law, for each time the voltage is doubled the current increases Impedance relay Reactance relay Mho relay Frequency relay.

Important Points: Impedance relay is a voltage restrained overcurrent relay. Reactance relay is an overcurrent relay with directional restraint. Mho relay is a voltage restrained directional relay. Reactance relay is suitable for the protection of a short transmission line because its operation is independent of arc resistance.

The relay which is selected for a long transmission line should be less affected due to power swings. Hence Mho relay is preferred. Impedance relay is suitable for medium transmission lines. Under frequency relay Buchholz relay Distance relay Differential relay. Differential relay: Differential relay operation depends on the phase difference of two or more electrical quantities. It works on the principle of comparison between the phase angle and the magnitude of the same electrical quantities.

The differential relay is used for the protection of the feeder, large busbars, etc. Distance protection schemes are commonly employed for providing the primary or main protection and backup protection for AC transmission line and distribution line against three-phase faults, phase-to-phase faults, and phase-to-ground faults.

Under frequency relay: Under frequency relay is used to protect the alternator when the frequency drops below the operating frequency. Under frequency occurs due to turbine low speed, grid frequency fluctuation, etc. The generator can tolerate moderate under frequency operation provided voltage is within an acceptable limit. Buchholz relay: Buchholz relay protects the transformer from internal faults.

It is the gas actuated relay. The Buchholz relay is placed between the main tank and the conservator. Buchholz relay is used in the transformer having a rating higher than KVA. It is not used in a small transformer because of economic considerations. Undervoltage relay Translay relay Thermal relay Buchholz relay. Which is the opposite case as given in the question. Distance Relay: A distance protection relay is a name given to the protection, whose action depends on the distance of the feeding point to the fault.

The time of operation of such protection is a function of the ratio of voltage and current, i. This impedance between the relay and the fault depends on the electrical distance between them. Types of distance relays are impedance relays, reactance relays, and the mho relays. Circuit breaker Rating Oil circuit breaker 3. More than ohms More than ohms Less than ohms Less than ohms. Pilot wire: Whenever a transmission line or equipment is to be protected by using distance relay or differential relay or Merz-price protection.

A wire is connected between the CT which is located at different ends of the protection zone. This wire provides the path for the circulating current produce in an abnormal condition, which is sensed by the relay and therefore is tripped; this wire is known as pilot wire. Depending on the input supply voltage, fuses are the AC fuses and the DC fuses.

Concept: Induction type relay: The induction type relays are also called magnitude relays. These relays work on the principle of the induction motor or an energy meter. In these relays, a metallic disc is allowed to rotate between the two electromagnets. The coils of the electromagnets are energized with the help of alternating currents.

The torque is produced in Induction relays due to the interaction of one alternating flux with eddy currents induced in the rotor by another alternating flux. The two fluxes have the same frequency but are displaced in time and space. As the interaction of alternating fluxes is the base of operation of Induction relays. These are not used for the d. These are widely used for protective relaying involving only a.

Based on the construction, the various types of induction relays are: 1 Shaded pole Relays 2 Watt-hour meter Relays 3 Induction cup Relays Explanation: So, The relaxation pole relay is not an example of an induction type relay. Important Point: Advantages of vacuum circuit breaker: They are compact, reliable and have a longer life There are no fire hazards There is no generation of gas during and after the operation They can interrupt any fault current.

The important feature of a VCB is that it can break any heavy fault current perfectly just before the contacts reach the definite open position. They require little maintenance and are quiet in operation They can withstand lightning surges They have low arc energy They have low inertia and hence require smaller power for the control mechanism Download Solution PDF Share on Whatsapp. An alternator A transformer A transmission line A bus bar.

Negative sequence relay: It protects generators from the unbalanced load by detecting negative sequence current. A negative sequence current may cause a dangerous situation for the machine.

Phase to phase fault mainly occurs because of the negative sequence component. The negative sequence relay has earthing which protects from phase-to-earth fault but not from phase-to-phase fault.

Sensitivity Selectivity Stability Reliability. Protective system: A protection system is designed for the continuous operation of the power system and it should ensure maximum continuity of service with minimum damage to life, equipment, and property. Objectives of system protection: Speed of operation: Protection system should ensure minimum fault duration and consequently no equipment damage. Under this objective, the Relay system is designed to operate under a predetermined condition Selectivity: The protection system should ensure max continuity of service with minimum system interruption.

It has two aspects Dependability: It should operate whenever it is required. Security: It should not operate whenever it is not required.

Buchholtz relay Admittance relay Directional over current relay Directional switched relay. It is inherently a directional relay as it detects the fault only in the forward direction. Inverse time current characteristic Linear time current characteristic Square law time current characteristic None of the above. Rewireable fuse works on inverse time-current characteristics Rewireable fuse is also known as the kit-kat fuse Whenever the current exceeds the predefined value, the flow of current heats the coil and melts it and the fuse is blown out Once the fuse is blown out, it can be reused by replacing the fuse element with a new one The normally used fuse wires are lead and aluminium Tinned copper and an alloy of tin-lead can also be used Download Solution PDF Share on Whatsapp.

Earthing screen Over head ground wires Lightning arrester None of these. In this way, station equipment is protected against damage The limitation of this method is that it does not provide protection against the travelling waves which may reach the equipment in the station Download Solution PDF Share on Whatsapp. Inverse direct maximum time lag Inverse definite minimum time lag Inverse definite maximum time lag None of these. IDMT inverse definite minimum time lag relay: In IDMT relay the operating time is approximately inversely proportional to the fault current near the pickup value and becomes substantially constant slightly above the pickup value of relay.

This is achieved by using a core of the electromagnet which gets saturated for currents slightly greater than the pickup current.

The sensitivity of this relay is high and the cost is also very high. It gives inverse time-current characteristics at lower values of fault current and definite time characteristics at higher values. Used in the backup protection of the transformer against external short circuits.

Protection requirements for industrial plants, cogeneration, and interconnection with the utility power system are explained in detail. This course covers the subject of power system protection from a practical perspective, and includes important functional aspects such as testing and coordination of protection systems.

This course is designed for individuals who are involved with industries and utilities which depend on proper system protection for operational efficiency and minimizing damage to equipment. This minimizes the portion of the system affected by a fault or other disturbance. At the substation level, feeder breakers should trip before the main. Likewise, downstream panel breakers should trip before the substation feeder supplying the panel.

Power System Protection And Coordination of various electrical equipment and apparatus requires a good understanding of phase and ground short circuit currents, detection, and safe clearing of the faulted equipment. Large or small, each and every industrial, commercial and institutional organization needs to understand how to protect their investment in their electric power systems. To do this properly, companies need to know how to perform an electrical protection analysis of all the parts of their power system: such as analyse fault data, come up with protection settings, then get all of the components of their plant to be controlled by the operators who are responsible for integrating their power system into communication and data acquisition modes.

Students will be learn the essentials of electrical protection design, relay coordination, and fusing fundamentals, breaker fundamentals. Students will be provided with an understanding of digital protective relaying, as we go through practical examples of generator, feeder, motor, and transformer electrical protection. Successful completion of this course qualifies delegates to receive a certificate of course completion with indicated CEUs.

One CEU is equivalent to 10 professional development hours of instruction. We can present this Protective Relay Training - Basic to your electrical engineering and maintenance staff, through our Live Online Training Platform, tailored to your specific equipment and requirements.

We are ready to help design this program for you. Click on the link below to request a FREE quotation. Protective Relay Training - Basic. Gain valuable experience in utility and industrial electrical system analysis, protection, control, communication, and automation Learn the latest trends in evolving electrical protection standards, design methods, and new technologies Gain Valuable knowledge of electrical power system analysis and short circuit calculations, time current coordination curves, fusing fundamentals, and more!!

Learn how to keep your electrical system engineers, operators and project managers on track by using the latest relay protection techniques Large or small, each and every industrial, commercial and institutional organization needs to understand how to protect their investment in their electric power systems.

Note: It will be beneficial if students will have own laptop. To provide a practical understanding and selection of protective device relay applications and protective relay schemes for industrial and electrical power systems and equipment.

Describe current and voltage transformers and their impact on protection relay settings and schemes. Apply and calculate settings for motor, generation, industrial distribution and transmission lines, transformer, bus, breaker failure protection schemes, load shedding, power source transfers and arc-flush mitigation.

Refresh your knowledge of the basic industrial system protection techniques including fault analysis and overvoltage assessment.