b) CUJT c) Independent of zone The relaying quantity such as voltage/current is rectified and measured. Characteristic Functions of Protection Relay : Characteristic Functions of Protection Relay elements using different operating principles. Relay is a switch which senses fault in a system and once fault is sensed by the Relay, it issues trip command to the Circuit Breaker, CB to isolate the faulty section of the network from the healthy section. Economics of Operation page-2, Objective Type Question or MCQ of B. c) Transformer The In a static relay, the measurement is performed by static councils. d) None of these It is possible to work on ungrounded systems of … What does the first part consist of? c) Before the transformer : 4 The first protective relays were electromagnetic devices, relying on coils operating on moving parts to provide detection of abnormal operating conditions such as over-current, overvoltage, reverse power flow, over-frequency, and under-frequency. b) In two zones The static relay only gives the response to the electrical signal. 10% of 3 sec. As the time setting multiplier is 0.1 here, actually the moving parts of the relay have to travel only 0.1 × 100% or 10% of the total travel distance, to close the relay contacts. d) None of the above, Multiple Choice Question (MCQ) of Electronics page-13:181. The term ‘static’ implies that the relay has no moving mechanical parts in it. The electrical wiring to the motor must be verified to ensure that all the connections are made in accordance with the requirements. This technical co… 2. Ans: (d), a) Hinged armature type c) Transformers Static relay: translation The conventional relay type of electromagnet relay s can be replaced by static relay which essentially consists of electronic circuitry to develop all those characteristics which are achieved by moving parts in an electro-magnetic relay. Note ... (tripping) direction. Case-2 for New CT: New CT Ratio- 800/5A. Static Relay: ( 2nd Generation ) Characteristic curve is obtained through use of RC timing circuits No moving parts Used to retrofit electro-mechanical relays Fast reset Less maintenance Static Relay: ( 2nd Generation ) Set Value. A relay is automatic device which senses an abnormal condition of electrical circuit and closes its contacts. The Relay detects the abnormal condition by continuously monitoring electrical quantities which are different All versions are available with an S-value of : 0.5, 0.66, 0.80 and 0.85. In which of the following device the base resistors are not added in the package but added externally? Instantaneous relay is. in a d.c. polarized relay contact A is closed when current in the operating winding flows in one direction contact B will be …, Static Relay : The term ‘static relay’ is generally referred to a relay incorporating solid state components like transistors, diodes, resistors, capacitors, etc. Compared to the Electromechanical Relay, the Solid Static relay has longer life-span, decreased noise when operates and faster respond speed. In individual relays, there is a wide variation. d) None of these b. a. Where, Z is the fault impedance and is equal to ratio of V and I, Z R is the replica impedance in the relay, ɸ is the phase angle between V and I and θ is the relay characteristic angle. The trip circuit operates the circuit breaker which isolates the faulty section. Introduction of Static relay The relay which does not contain any moving parts is known as the static relay. In an actual relay, I threshold can be adjusted. b) Non-linear characteristic - from the table α = 0.02, K = 0.14 - pick-up current setting = 1000 A x 0.8 = 800 A d) 110 Kms Actual tripping of a static relay is obtained by. a) Semiconductors b) Center of the line d) Inner and bound electrons are always present in the semiconductor. b) 50 Kms Hence, actual operating time of the relay is 3 × 0.1 = 0.3 sec. d) All of these In this relay operating torque is obtained by the volt-amperes element and the controlling element is developed due to the voltage element. Micro controller based over voltage static Relay. correlates to the actual tripping of a Static VAr Compensator (SVC). The conduction in JEFT is always by the c) UJT The moving parts are absent. Tripping of the bus is obtained when both the SR and dR operate simulta- neously. The mho function uses the current and voltage measured at the relay to determine if the ... than would be obtained with a self-polarized mho function. AC - DC Conversion. In an impedance relay, fault current is maximum if fault occurs near the, a) Relay a) Hinged armature type b) Polarized type c) Balanced beam type d) All of these Ans: (a) 35. A mho relay using the induction cup structure is shown in the figure below. Medium voltage switchgears are used for switching medium voltage loads through associated control, measuring, protective and regulating equipment. It means a mho relay is a voltage controlled directional relay. In a static relay the measurement is carried out by static circuits consisting of comparators, level detectors, filter etc while in a conventional electro-magnetic relay it is done by comparing operating torque (or force) with restraining torque (or force). Ans: (d), a) Straight line characteristic Electronic Relay. c) Both (a) and (b) Relay Pickup current (Primary) = Plug Position (PSM) * Rated CT Primary current. Ans: (a), a) Generators Definition of Protective Relay. d) Over head lines d) Surge attenuators c) Surge absorbers The moving parts are present only in the actual tripping circuit and not in the control circuit. The output is obtained from the output devices only when the measurand has the well-defined value. This obtained by converting 230V a.c. to 24V d.c. and in some cases station battery voltage of 110V to 24V d.c. Comprator:It compares the actual quantity with the pre-set quantity. These along with the other Semiconductor production of static relays. In such type of relays, the output is obtained by the static components like magnetic and electronic circuit etc. b) Bound electrons are always present in the semiconductor. An 1000 Amp breaker protected by relay with Standard Inverse characteristic. b) Minority carriers Lower part: The lower part of the Buchholz relay is concerned with the detection of serious or major faults and thus completes the trip circuit to open the circuit breaker operating the transformer. a) Majority carriers Economics of Operation page-5, Objective Type Question or MCQ of B. Economics of Operation page-4, Objective Type Question or MCQ of B. Thus there will be three converter elements, one for each phase, but thereafter the rest of …, Polarised Relay : This Polarised Relay is very frequently employed where operation is required in two directions. Multiple Choice Question (MCQ) of Electronics page-16:226. d) The saturation voltage VCE for silicon transistor is lower than germanium transistor. Introduction to Static Relays: Characteristic Functions of Protection Relay: Characteristic Functions of Protection Relay elements using different operating principles. https://emadrlc.blogspot.com/2014/04/power-system-protection-course.html Ans: (c), a) Solid grounding The output device is activated and gives the tripping command to the trip circuit. Ans: (d), a) SCR c) Balanced beam type When a differential current exceeding the setting of the relay flows, timer T1 is reset and timer T2 … Q5. b) Earth fault are utilized to disconnect the fault 4.6.1. Time vs. PSM Curve of Relay Static Relay: The term ‘static relay’ is generally referred to a relay incorporating solid state components like transistors, diodes, resistors, capacitors, etc.In this type of relay, the functions of comparison and measurement are performed by static circuits wherein there are no moving parts. Multiple Choice Question (MCQ) of Electronics page-17:241. b) Polarized type a) SCR b) Thyristors c) UJT d) None of these Ans: (d) 34. Which of the following statement is true? Economics of Operation page-6, Objective Type Question or MCQ of B. A variety of control and interlocking schemes are used to achieve the above stated objectives. b) Surge divertors Static relay consists of following units for operation: Auxiliary Voltage Supply:24 V D.C. supply is required for energizining the circuitry of the static relay. When no current is flowing for a time exceeding 1/4f seconds, timer T2 is held reset and the differential relay that may be controlled by these timers is blocked. Which of the following statement is correct? The output device is activated and gives the tripping command to the trip circuit. The plug …, Influence of Static Protective Relays : Influence of Static Protective Relays on the associated equipment like current transformers, voltage transformers, etc, Current Transformers Burdens on current transformers have a great influence on their design and for a long time the problems of …, Level Detector : Schmitt trigger or level detector circuits are very often employed in static relay circuits as a final stage before the trip coil circuit of the circuit breaker. The function will not oper-ate for an inductive fault behind them. In the above figure, the relay circuit is divided into three parts. a) UJT Distance relay tripping characteristic itself depends on the power system structural conditions, i.e. b) The saturation voltage VCE for germanium transistor is more than silicon transistor. a) The saturation voltage VCF of silicon transistor is more than germanium transistor. This relay can be used to isolate faults in transmission lines based on the conversion of 3-phase currents from analog to digital values and instantaneously issuing a trip signal if the actual line current is greater than preset value. For example in an over-current relay it will compare the actual current supplied by … Current Sampling From CTs. Primary winding of a current CT which is connected in series with the line to be protected. c) Free electrons are always present in the semiconductor. i.e. The stability setting applies only during external faults. a) Inner electrons are always present in the semiconductor. d) Electrons Delays of the order of microseconds can be obtained …, Transistor Switch Circuit : Transistor Switch Circuit – The characteristics of modern transistors are specially suited to the functional requirements mentioned above. Answer / Hide Answer Advantages of static relays considerably reduced thus smaller CT.s can be used be... 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