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The buchholz relay is one type of  relay which is used in the oil filled power transformerand is for the safety device .
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Description : Buchholz relay is used as a safety device with respect to which of the following? A) Audio transformers B) Oil filled power transformers C) Air core transformer D) None of these

Answer : Buchholz relay is used as a safety device with respect to which of the following? A) Audio transformers B) Oil filled power transformers C) Air core transformer D) None of these

Description : What is the use of Buchholz relay in transformer?

Answer : This is a transformer that is used to step up and down current. 

Description : Describe the construction and Operation of Buchholz relay with neat labeled diagram.

Answer : Construction of Buchholz Relay: It takes the form of a domed vessel placed in the connecting pipe between the main tank and the conservator. The device has two elements. The upper element ... manner that it senses the sudden violent movement of oil/gas from transformer tank to conservator. 

Description : Explain Buchholz relay with neat labelled diagram.

Answer : Buchholz relay: The relay is located in the path of the oil from transformer tank to conservator. As seen from diagram, the upper mercury switch operates the alarm circuit due to tilting of the ... manner that it senses the sudden violent movement of oil from transformer tank to conservator.

Description : Buchholz relay is  (1) located in the conservator tank  (2) located in the transformer tank itself  (3) connected in the pipe connecting main tank of transformer and conservator  (4) installed in the circuit breaker

Answer : Buchholz relay is connected in the pipe connecting main tank of transformer and conservator 

Description : A Buchholz relay is used for:  A) Protection of a transformer against all internal faults B) Protection of a transformer against external faults C) Protection of a transformer against both internal and external faults D) Protection of instrument transformers and bus bars 

Answer : A Buchholz relay can be installed on oil cooled transformers.

Description : What is phase failure relay and how it's work?

Description : What is Relay? A. which transfer power B. opens or closes an auxiliary circuit C. used for short circuit only D. converts AC to DC 

Answer : opens or closes an auxiliary circuit

Description : what is reverse power relay?

Answer : Thereverse powerrelay is a directional protective relay that prevents power from flowing in the reverse direction. Read our article going back ... it all to be up to date. And if you do, read it anyway just to check if youreallydo!

Description : main parts of Relay

Answer : Coil, plunger, contacts, springs, connecting terminals and enclosure.

Description : function of equipment’s used in sub-stations : (i) Earth Switch (ii) Relay (iii) Lighting Arrester (iv) Auxiliary transformer 

Answer : (i) Earth Switch   It's function is to discharge the ground capacitance when line is open circuited for maintenance purpose by isolator.) Earthing switch is inter - locked with isolator from the safety point ... 3-ph, 4wire, 400V) to give supply to control room, area lighting, staff quarters etc, 

Answer : Mho distance relays are widely used for the protection of uncompensated and series compensated transmission lines in order to determine the presence and location of faults.

Description : Draw a neat labeled diagram to show protective system for AC traction and give the function of each relay used in it. 

Answer : Protective system for AC traction:  Function Of Each Relay: For transformer -  Inverse time over current relay- as back up protection on primary (HV side) over current ... against faults near substation  Under voltage relay - protection against faults far away from substation

Description : Draw a neat sketch of earth fault protection of auxiliary circuit of electric loco. State the function of relay and isolating resistance.

Answer : Ans: Earth fault protection for auxiliaries in Loco: Function of relay: The earth fault occurring anywhere in the auxiliary circuit gets monitored by the relay which acts to trip the main CB. Function of ... star point to earth through a high resistance so that the relay operation is avoided.

Description : For a traction transformer circuit breaker state: 1) Rated current and rupturing capacity 2) Any two tests it should be capable of withstanding 3) Overall tripping time and relay time.

Answer : Ans: 1) Rated current --- 750 A and Rupturing capacity --- 500 MVA  2) Any two tests it should be capable of withstanding --- Breaking test , Reclosing test , Endurance test ( any two )  3) Overall tripping time --- 0.14 sec and Relay time --- 0.04 sec 

Description : Explain the construction and working of electronic overload relay.

Answer : Electronic overload relay consists of a solid state circuit that operates the electromagnetic switching device to protect the load from overload. The load current is sensed by using a current ... sections. The output of relay driver section sends trip signal to electromagnetic switching device.

Description : Describe the operation of solid state relay.

Answer : Solidstate relay is electronic equivalent of an electromechanical relay. It consists of controlled power semiconductor switch like triac. There are four terminals. Two are the power terminals for load and two control ... is turned ON. When triac is ON, the load is connected to AC supply

Description : A series resistance is added to the over-current relay in a bus bar differential protection scheme which: a. Helps to develop some voltage across it which otherwise should appear across the relay and is ... the effects of CT saturation and lowers the pickup value of the relay d. All of the above 

Answer : A series resistance is added to the over-current relay in a bus bar differential protection scheme which: a. Helps to develop some voltage across it which otherwise should appear across the relay and is ... the effects of CT saturation and lowers the pickup value of the relay d. All of the above 

Description : The operating characteristics of a reactance type distance relay (A) a stepped waveform for increasing reactance (B) a straight line for a constant reactance (C) a circle for a constant reactance (D) a set of circles for variable reactances

Answer : The operating characteristics of a reactance type distance relay a straight line for a constant reactance

Description : In induction type directional over current relay the driving torque is due to interaction of magnetic fields derived from (A) current in the potential coil (B) both voltage and current in the ... (C) directional element and non-directional element (D) non-directional element and the trip circuit

Answer : In induction type directional over current relay the driving torque is due to interaction of magnetic fields derived from directional element and non-directional element

Description :  Mho relay is usually employed for protection of (A) Short lines (B) Medium lines (C) Long lines (D) Any line

Answer : Mho relay is usually employed for protection of long lines.

Description : Mho relay is   (a) current restrained current relay. (b) voltage restrained directional relay. (c) current restrained directional relay. (d) voltage restrained current relay. 

Answer : Mho relay is voltage restrained directional relay. Mho Relay is also known as admittance relay. 

Description : In a static over-current relay, inverse time characteristics are obtained by   (a) A differentiating circuit (b) An integrating circuit (c) A transistor amplifier (d) A transistor switch

Answer : B

Description : By burden on the relay, we generally mean   (a) Current rating of relay (b) Voltage rating of relay (c) Volt-ampere rating of relay (d) Watt rating of relay 

Description : Kick fuses are used across relay coils to prevent relay operation during   (a) Heavy external faults (b) Inrush current of transformer when they are energised (c) Line to ground faults (d) Bolted faults  

Description : Inverse definite minimum time lag relay is also called  (A) pilot relay  (B) differential relay (C) over current relay (D) directional overcurrent relay

Description : What is the difference between relay and contactor?

Answer : Relay have smaller ratings. Contactor is a high rating relay.

Description : What is the time of operation of a relay of rating 5 amp 2.2 sec, IDMT and having a relay of setting of 125% Tms = 0.6 It is connected to a supply circuit through a CT, 400 ratio. The fault current is 400 amp.

Answer : 1.92 sec is the time of operation of a relay of rating 5 amp 2.2 sec, IDMT and having a relay of setting of 125% Tms = 0.6 It is connected to a supply circuit through a CT, 400 ratio. The fault current is 400 amp.

Description : What is the difference between a switch and a relay?

Answer : Switch is simply a mechanical contact mechanism and relay is a electromagnetic switch . Switch can be direct mechanically turn on and off but relay can be operated by energising coil .

Description : ____ is used latching, locking, triggering. A. Solenoid B. Relay C. Linear Actuator D. Servo motors

Answer : A. Solenoid 

Description : The part of the human brain which is an important relay station for the sensory impulses and also is the origin of many of the involuntary acts of the eye such as the narrowing of the pupil in bright light is the: a) hypothalamus b) midbrain c) corpus callosum d) cerebellum

Answer : ANSWER: B -- Midbrain

Description : Which of the following is widely used inside the telephone system for longhaul data traffic ? (A) ISDN (B) ATM (C) Frame Relay (D) ISTN

Answer : (B) ATM

Description : With the help of neat diagram, explain operation of static relay.

Answer : Operation of Static Relay: Operation: 1) The solid-state component used are transistors, diodes, resistors, IC s, capacitor etc. The function of comparison and measurement are accomplished by ... ) An auxiliary dc supply is provided for operation of static relay elements as shown in figure.

Description : Describe the operation of current differential relay with neat sketch.

Answer : Operation of Current Differential Relay: Figure shows an arrangement of an overcurrent relay connected to operate as a differential relay for alternator protection under fault conditon. ... current flows through relay coil, causing relay to operate for protection of alternator winding.

Description : With a neat sketch, explain the working of Thermal relay.

Answer : Working of Thermal Relay: 1) When the system is in normal operating condition, the heating element carries normal current from CT, this current produces heat = I2Rt. This heat ... of the spring releases which operates relay contacts resulting into providing trip signal to trip circuit.

Description : Define the following terms with respect to protective relays i) Relay time ii) Reset current iii) Plug setting multiplier and iv) Time setting multiplier

Answer : 1) Relay Time: The time interval between occurrence of fault and closure of relay contacts.  2) Reset Current: The value of current below which the relay resets and comes back to ... The adjustment arrangement provided for setting the operation time of relay is known as Time setting multiplier. 

Description : Draw a typical time-current characteristic for IDMT relay. 

Answer : Time-Current Characteristic for IDMT Relay:

Description : Draw the labeled interfacing diagram to interface relay with 89C51 microcontroller.

Answer : the labeled interfacing diagram to interface relay with 89C51 microcontroller

Description : Explain operation of balanced beam type relay.

Answer : Balanced Beam Type Relay: Under normal operating condition the current through relay coil is such that the beam is held in the horizontal position by the spring. When the fault occurs on the system the ... becomes greater than pick-up value and beam is attracted to close the trip circuit. 

Description : Explain MHO relay in detail.

Answer : MHO Relay: In this relay, poles 1, 2, 3 are energized by a voltage V through polarizing coil to produce flux, the capacitor connected provides phase shift. The left pole 4 is energized by a current which is the ... hence on the ratio (I/V) = Y i.e. admittance, hence called as MHO relay.

Description : Describe over current relay with time-current characteristic.

Answer : Over current relay with time-current characteristics:- 1. Definite time over current relay: Operating time is constant, the relays operates after a predetermined time when the current exceeds the pickup ... of fault current and definite time characteristics at higher values of fault current.

Description : Explain operation of µP based relay with block diagram

Answer : Operation of Microprocessor (µP) based relay: The inputs from the power system through CTs and PTS are received by the analog Input receiver; they are sampled simultaneously or ... compares the dynamic inputs and decides accordingly to generate trip/alarm signal to the output device.

Description : Explain construction and operation of induction type directional over current relay.

Answer : Directional overcurrent relay: Construction: It consists of two units: i) Non-directional Over-current unit ii) Directional power unit The directional unit consists of upper electromagnet ... closes the trip circuit. This operates circuit breaker which isolates the faulty section. 

Description : State any four relays used for catenary protection. State function of each relay.

Answer : Relays Used for Catenary Protection: 1. MHO relay: Wrong coupling protection. 2. MHO relay: Over current protection at farthest point. 3. Over current relay: Over current protection against faults near substation 4. Under voltage relay: Protection against faults far away from substation. 

Description : The reactance relay is essentially: A) an over-voltage relay with current restraint B) an over-voltage relay with directional restraint C) a directional relay with voltage restraint D) a directional relay with current restraint 

Answer : reactance relay is basically a overcurrent relay with directional limitations. it has basically two elements first one is overcurrent which provides positive torque and second one is overcurrent-voltage which provide directions.

Description : The operation of the relay which is most affected due to arc resistance is A) Mho relay B) Reactance relay C) Impedance relay D) All are equally affected

Answer : The operation of the relay which is most affected due to arc resistance is Mho relay

Description : Ratio relay by using line-to-neutral voltage protect (A) 3-phase faults (B) double line faults (C) double-line-to-ground faults (D) generator bus earth faults 

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