Why do we use O/C & E/F protection on both sides of transformer?

Why do we use O/C & E/F protection on both sides of transformer?
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1 Answer

Answer :

Power in feed exists on both ends.  
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Related questions

Why in DG E/F protection, we do not open class IV CB’s or supply CB’s?

Description : Why in DG E/F protection, we do not open class IV CB’s or supply CB’s?

Last Answer : Delta of aux. Transformer prevents E/F currents from grid into DG neutral.  

Component F in the illustrated device is for _________. EL-0033 A. short circut protection B. latching the trip unit closed after resetting the breaker C. overload protection D. providing a flexible connection between the input terminal G and the tripping unit E

Description : Component F in the illustrated device is for _________. EL-0033 A. short circut protection B. latching the trip unit closed after resetting the breaker C. overload protection D. providing a flexible connection between the input terminal G and the tripping unit E

Last Answer : Answer: C

Why 100% winding protection is felt essential for main generator stator E/F protection? (Used in NAPS onwards?)

Description : Why 100% winding protection is felt essential for main generator stator E/F protection? (Used in NAPS onwards?)  

Last Answer : At MAPS 4% of winding is not protected. Earlier felt that the Electro magnetic stress due high external fault currents near 4% of neutral may not be high to cause E/F here. But now felt that the mechanical stress can leads to E/F. 

Purpose of standby E/F protection in SUT/UT?

Description : Purpose of standby E/F protection in SUT/UT? 

Last Answer : Back up for LV winding, LV neutral CT- CDG 12 – resistance earthing – relay set high time delay to discriminate with LV feeder and trip transformer if sustained E/F, also protects neutral earthing resistor.

What parameters or technical particulars are important to be considered while designing protection scheme of the transformer?

Description : What parameters or technical particulars are important to be considered while designing protection scheme of the transformer?

Last Answer : 1.Network Diagram showing the position of the transformer in the system 2.kVA or MVA rating of the transformer 3.Fault Level at the transformer 4.Voltage Ratio 5.Winding Connections 6.Per Unit ... Oil Filled 11.Length and area of cross section of the connecting leads between CTs and Relay Panel

How Transformer Protection provided for internal faults?

Description : How Transformer Protection provided for internal faults?

Last Answer : 1.Bucholz Relay (1st Stage Alarm and 2nd Stage Trip) 2.Sudden Pressure Relay (1st Stage Alarm and 2nd Stage Trip) 3.Pressure Relief Valve (1st Stage Alarm and 2nd Stage Trip) 4.Pressure Switch ... 8.Gas Temperature Indicator (Alarm) 9.Silicon Breather (Passive - no alarm) 10.Smoke Detector (Alarm)

What is over fluxing protection in transformer?

Description : What is over fluxing protection in transformer?

Last Answer : If the turns ratio of the transformer is more than 1:1, there will be higher core loss and the capability of the transformer to withstand this is limited to a few minutes only. This phenomenon is called over fluxing.

What are the problems arising in differential protection in power transformer and how are they overcome?

Description : What are the problems arising in differential protection in power transformer and how are they overcome?

Last Answer : 1. Difference in lengths of pilot wires on either sides of the relay. This is overcome by connecting adjustable resistors to pilot wires to get equipotential points on the pilot wires. 2. ... harmonic restraining unit is added to the relay which will block it when the transformer is energized.

Mention the short comings of Merz Price scheme of protection applied to a power transformer.

Description : Mention the short comings of Merz Price scheme of protection applied to a power transformer.

Last Answer : In a power transformer, currents in the primary and secondary are to be compared. As these two currents are usually different, the use of identical transformers will give differential current, and ... turn-ratio are used, the differential current may flow through the relay under normal condition.

What is the in built protection for transformer?

Description : What is the in built protection for transformer?

Last Answer : PRV to protect from over pressurization of tank due to the release of gases, oil etc. This is the replacement for the explosion vent. 

Why delta – delta CT’s are used for star – star transformer differential protection?

Description : Why delta – delta CT’s are used for star – star transformer differential protection?

Last Answer : Say primary neutral is not solidly earthed. Then for any earthfault on secondary terminal, the primary current distribution is so for external fault, the differential is likely to operate if sequence current ... into relay. The 2:1:1 distribution is possibly only for core type or delta tertiary.

Why the earthing transformer primary voltage is 16.5 kV rated in main generator even though actual voltage during the E/F is root 3 times less?

Description : Why the earthing transformer primary voltage is 16.5 kV rated in main generator even though actual voltage during the E/F is root 3 times less?

Last Answer : The transformer should not saturate during E/F otherwise it will cause ferroresonance with the GT winding capacitance. Dangerous O/V and neutral shifting will occur. During loss of load or field ... saturation. Saturation can also occur due to point on wave of application causing flux doubling. 

In the illustrated 450 VAC system, what should be provided between the bus and the device labeled 'F'? EL-0003 A. a potential transformer B. a current transformer C. an emergency disconnect device D. an audible alarm and indicating light

Description : In the illustrated 450 VAC system, what should be provided between the bus and the device labeled 'F'? EL-0003 A. a potential transformer B. a current transformer C. an emergency disconnect device D. an audible alarm and indicating light

Last Answer : Answer: A

For V/F control, when frequency is increased in transformer a) Core loss component current increases, Magnetizing component current decreases b) Core loss component current increases, Magnetizing component current increases c) Core loss component current decreases, Magnetizing component current decreases d) Core loss component current decreases, Magnetizing component current increases

Description : For V/F control, when frequency is increased in transformer a) Core loss component current increases, Magnetizing component current decreases b) Core loss component current increases, ... component current decreases d) Core loss component current decreases, Magnetizing component current increases

Last Answer : Ans: Core loss component current decreases, Magnetizing component current decreases

In a transformer the voltage regulation will be zero when it operates at (A) unity p.f. (B) leading p.f. (C) lagging p.f. (D) zero p.f. leading.

Description : In a transformer the voltage regulation will be zero when it operates at (A) unity p.f. (B) leading p.f. (C) lagging p.f. (D) zero p.f. leading.

Last Answer : (B) leading p.f.

Why we do 2 types of earthing on transformer i.e.: body earthing & neutral earthing, what is function. I am going to install a 5oo kva transformer & 380 kva DG set what should the earthing value?

Description : Why we do 2 types of earthing on transformer i.e.: body earthing & neutral earthing, what is function. I am going to install a 5oo kva transformer & 380 kva DG set what should the earthing value?

Last Answer : The two types of earthing are Familiar as Equipment earthing and system earthing. In Equipment earthing: body (non conducting part) of the equipment should be earthed to safeguard the human ... earthing will be further classified into directly earthed, Impedance earthing, resistive (NGRs) earthing.

What is the supply rated o/p if two single phase transformer connect to give three phase o/p from a three phase I/p?

Description : What is the supply rated o/p if two single phase transformer connect to give three phase o/p from a three phase I/p?

Last Answer : A. Each transformer is only capable of supplying 86.6%of its o/p rating

How to connect two single phase transformer to give three phase o/p from a three phase I/p ?

Description : How to connect two single phase transformer to give three phase o/p from a three phase I/p ?

Last Answer : A. They would have to connect in an open-delta.

What is the operating point in the Magnetising characteristic of protection CT & measuring CT?

Description : What is the operating point in the Magnetising characteristic of protection CT & measuring CT? 

Last Answer : Protection CT – Operation at ankle point only. Measuring CT – Operation from ankle to knee point 

In the figure, arcs and drawn by taking vertices A, B and C of an equilateral triangle of side 10 cm to intersect the sides BC, CA and AB at their respective mid-points D, E and F. Find the area of teh shaded region. [use π = 3.14] -Maths 10th

Description : In the figure, arcs and drawn by taking vertices A, B and C of an equilateral triangle of side 10 cm to intersect the sides BC, CA and AB at their respective mid-points D, E and F. Find the area of teh shaded region. [use π = 3.14] -Maths 10th

Last Answer : Step-by-step explanation: We have been provided that, Triangle ABC is an Equilateral triangle. Side of triangle is = 10 cm The arcs are drawn from each vertices of the triangle. We get three sectors ... portion is, Remaining area = Area of triangle ABC - Area of all the sectors 39.25cm square

The attributes of a file are. a. Name b. Identifier c. Types d. Location e. Size f. Protection g. Time, date and user identification h. Allof these

Description : The attributes of a file are. a. Name b. Identifier c. Types d. Location e. Size f. Protection g. Time, date and user identification h. Allof these

Last Answer : h. Allof these

5. In a parallelogram ABCD, E and F are the mid-points of sides AB and CD respectively (see Fig. 8.31). Show that the line segments AF and EC trisect the diagonal BD. -Maths 9th

Description : 5. In a parallelogram ABCD, E and F are the mid-points of sides AB and CD respectively (see Fig. 8.31). Show that the line segments AF and EC trisect the diagonal BD. -Maths 9th

Last Answer : . Solution: Given that, ABCD is a parallelogram. E and F are the mid-points of sides AB and CD respectively. To show, AF and EC trisect the diagonal BD. Proof, ABCD is a parallelogram , AB || CD also, ... (i), DP = PQ = BQ Hence, the line segments AF and EC trisect the diagonal BD. Hence Proved.

D, E and F are respectively the mid-points of the sides AB, BC and CA of a triangle ABC. -Maths 9th

Description : D, E and F are respectively the mid-points of the sides AB, BC and CA of a triangle ABC. -Maths 9th

Last Answer : Since the segment joining the mid points of any two sides of a triangle is half the third side and parallel to it. DE = 1 / 2 AC ⇒ DE = AF = CF EF = 1 / 2 AB ⇒ EF = AD = BD DF = 1 ... △DEF ≅ △AFD Thus, △DEF ≅ △CFE ≅ △BDE ≅ △AFD Hence, △ABC is divided into four congruent triangles.

In the fig, D, E and F are, respectively the mid-points of sides BC, CA and AB of an equilateral triangle ABC. -Maths 9th

Description : In the fig, D, E and F are, respectively the mid-points of sides BC, CA and AB of an equilateral triangle ABC. -Maths 9th

Last Answer : Since line segment joining the mid-points of two sides of a triangle is half of the third side. Therefore, D and E are mid-points of BC and AC respectively. ⇒ DE = 1 / 2 AB --- (i) E and F are the mid - ... CA ⇒ DE = EF = FD [using (i) , (ii) , (iii) ] Hence, DEF is an equilateral triangle .

ABCD is a trapezium with parallel sides AB = a cm and DC = b cm . E and F are the mid - points of the non - parallel sides . -Maths 9th

Description : ABCD is a trapezium with parallel sides AB = a cm and DC = b cm . E and F are the mid - points of the non - parallel sides . -Maths 9th

Last Answer : Clearly, EF = AB + DC / 2 = a + b / 2 Let h be the height , then ar(Trap. ABFE) : ar(Trap. EFCD) ⇒ 1/2 [a + (a+b / 2)] × h : 1/2 [b + (a+b / 2)] × h ⇒ 2a + a + b / 2 : 2b + a + b / 2 ⇒ 3a + b : 3b + a

E and F are respectively the mid-points of the non-parallel sides AD and BC of a trapezium ABCD. -Maths 9th

Description : E and F are respectively the mid-points of the non-parallel sides AD and BC of a trapezium ABCD. -Maths 9th

Last Answer : According to question the mid-points of the non-parallel sides AD and BC of a trapezium ABCD.

D, E and F are respectively the mid-points of the sides AB, BC and CA of a triangle ABC. -Maths 9th

Description : D, E and F are respectively the mid-points of the sides AB, BC and CA of a triangle ABC. -Maths 9th

Last Answer : Since the segment joining the mid points of any two sides of a triangle is half the third side and parallel to it. DE = 1 / 2 AC ⇒ DE = AF = CF EF = 1 / 2 AB ⇒ EF = AD = BD DF = 1 ... △DEF ≅ △AFD Thus, △DEF ≅ △CFE ≅ △BDE ≅ △AFD Hence, △ABC is divided into four congruent triangles.

In the fig, D, E and F are, respectively the mid-points of sides BC, CA and AB of an equilateral triangle ABC. -Maths 9th

Description : In the fig, D, E and F are, respectively the mid-points of sides BC, CA and AB of an equilateral triangle ABC. -Maths 9th

Last Answer : Since line segment joining the mid-points of two sides of a triangle is half of the third side. Therefore, D and E are mid-points of BC and AC respectively. ⇒ DE = 1 / 2 AB --- (i) E and F are the mid - ... CA ⇒ DE = EF = FD [using (i) , (ii) , (iii) ] Hence, DEF is an equilateral triangle .

ABCD is a trapezium with parallel sides AB = a cm and DC = b cm . E and F are the mid - points of the non - parallel sides . -Maths 9th

Description : ABCD is a trapezium with parallel sides AB = a cm and DC = b cm . E and F are the mid - points of the non - parallel sides . -Maths 9th

Last Answer : Clearly, EF = AB + DC / 2 = a + b / 2 Let h be the height , then ar(Trap. ABFE) : ar(Trap. EFCD) ⇒ 1/2 [a + (a+b / 2)] × h : 1/2 [b + (a+b / 2)] × h ⇒ 2a + a + b / 2 : 2b + a + b / 2 ⇒ 3a + b : 3b + a

E and F are respectively the mid-points of the non-parallel sides AD and BC of a trapezium ABCD. -Maths 9th

Description : E and F are respectively the mid-points of the non-parallel sides AD and BC of a trapezium ABCD. -Maths 9th

Last Answer : According to question the mid-points of the non-parallel sides AD and BC of a trapezium ABCD.

D,E and F are the mid-points of the sides BC,CA and AB,respectively of an equilateral triangle ABC.Show that △DEF is also an euilateral triangle -Maths 9th

Description : D,E and F are the mid-points of the sides BC,CA and AB,respectively of an equilateral triangle ABC.Show that △DEF is also an euilateral triangle -Maths 9th

Last Answer : Solution :-

E and F are respectively the mid-points of the non-parallel sides AD and BC of a trapezium ABCD. Prove that EF||AB and EF = 1/2 (AB +CD). -Maths 9th

Description : E and F are respectively the mid-points of the non-parallel sides AD and BC of a trapezium ABCD. Prove that EF||AB and EF = 1/2 (AB +CD). -Maths 9th

Last Answer : Solution :-

In the above figure ( not to scale ) the sides BA,BC and CA of` Delta ABC` are produced to D,F, and E respectively such that `/_ ACF= 120^(@)` and `/_

Description : In the above figure ( not to scale ) the sides BA,BC and CA of` Delta ABC` are produced to D,F, and E respectively such that `/_ ACF= 120^(@)` and `/_

Last Answer : In the above figure ( not to scale ) the sides BA,BC and CA of` Delta ABC` are produced to D,F, and E ... /_ BAE= 150^(@)`. Then `/_ ABC = ________`.

State use of any four relays for the protection of traction transformer.

Description : State use of any four relays for the protection of traction transformer. 

Last Answer : Relays for the protection of traction transformers:  Inverse time over current relay as back up protection on primary (HV side) - over current protection of transformer and other equipment.  ... .  Buchholz relay - protection from incipient earth or inter winding faults inside the transformer

What are the applications of step-up & step-down transformer?

Description : What are the applications of step-up & step-down transformer?

Last Answer : A:Step-up transformers are used in generating stations. Normally the generated voltage will be either 11kV. This voltage (11kV) is stepped up to 110kV or 220kV or ... and made available at consumer premises. The transformers used at generating stations are called power transformers.

What are the necessary tests to determine the efficiency, voltage regulation, and temperature rise of winding & insulation of transformer?

Description : What are the necessary tests to determine the efficiency, voltage regulation, and temperature rise of winding & insulation of transformer?

Last Answer : 1.Direct loading test 2.Open circuit test 3. Short circuit test 4. Sumpner's or back to back test

Why not high resistance for earth fault than using grounding transformer & resistor 0.45 ohms?

Description : Why not high resistance for earth fault than using grounding transformer & resistor 0.45 ohms?

Last Answer : It is mechanically unwide. Difficult to manufacture.  

Overfluxing protection is recommended for (a) distribution transformer (b) generator transformer of the power plant (c) auto-transformer of the power plant (d) station transformer of the power plant

Description : Overfluxing protection is recommended for (a) distribution transformer (b) generator transformer of the power plant (c) auto-transformer of the power plant (d) station transformer of the power plant

Last Answer : (b) generator transformer of the power plant

The inverse definite mean time relays are used for over current and earth fault protection of transformer against (a) heavy loads (b) internal short-circuits (c) external short-circuits (d) all of the above

Description : The inverse definite mean time relays are used for over current and earth fault protection of transformer against (a) heavy loads (b) internal short-circuits (c) external short-circuits (d) all of the above

Last Answer : (b) internal short-circuits

For which of the following ratings of the transformer differential protection is recommended ? (a) above 30 kVA. (b) equal to and above 5 MVA (c) equal to and above 25 MVA (d) none of the above

Description : For which of the following ratings of the transformer differential protection is recommended ? (a) above 30 kVA. (b) equal to and above 5 MVA (c) equal to and above 25 MVA (d) none of the above

Last Answer : (b) equal to and above 5 MVA

List two limitations of Differential-Protection scheme for transformer.

Description : List two limitations of Differential-Protection scheme for transformer.

Last Answer : Limitations of Differential Protection Scheme of Transformer:  1) Due to the magnetization characteristics of the CTs used, the ratio errors change with respect to the circulating currents.  2) ... & improper operation.  5) Inrush of magnetizing current may lead to inadvertent operation.

Explain over-current protection of transformer.

Description : Explain over-current protection of transformer.

Last Answer : Over-Current Protection of Transformer: Simple over-current & earth fault protection of transformer against external shortcircuit and excessive overloads is shown in the above figure. The ... trip command to the circuit breaker and the transformer is disconnected from load or fault.

Write down limitation of differential protection of transformer.

Description : Write down limitation of differential protection of transformer.

Last Answer : Limitations of differential protection of transformer: 1) Due to the magnetization characteristics of the CTs used, the ratio errors change with respect to the circulating currents. 2) The pilot wires ... current (higher imbalance) due to which accuracy of sensing & operation is decreased. 

The inverse definite mean time relays are used for over current and earth fault protection of transformer against?

Last Answer : The inverse definite mean time relays are used for over current and earth fault protection of transformer against internal short-circuits.

Which of the following statements is true concerning the motor controller diagram shown in the illustration? EL-0023 A. Terminal 'T2' is hot only on high speed. B. Both indicating lights will be lit on both high and low speeds as they are connected to the common lead when the motor is running. C. Overload protection is provided for high speed operation only. D. 'L2' is always connected to 'T2' whenever the motor is running.

Description : Which of the following statements is true concerning the motor controller diagram shown in the illustration? EL-0023 A. Terminal 'T2' is hot only on high speed. B. Both indicating lights will be lit on ... high speed operation only. D. 'L2' is always connected to 'T2' whenever the motor is running.

Last Answer : Answer: D

All electric cables passing through watertight bulkheads must be _____________. A. installed with watertight stuffing tubes B. grounded on both sides of the bulkhead C. fitted with unions on each side of the bulkhead D. welded on both sides of the bulkhead

Description : All electric cables passing through watertight bulkheads must be _____________. A. installed with watertight stuffing tubes B. grounded on both sides of the bulkhead C. fitted with unions on each side of the bulkhead D. welded on both sides of the bulkhead

Last Answer : Answer: A

What is the purpose of the 'annunciator module' (6000F35) shown in the illustration? EL-0094 A. Provide an input to the setpoint module. B. Drive the alarm lamp and, through the controller, the horn. C. Deliver +5 and +24 volts to their respective power supplies. D. Connect 24 volts to both sides of the horn.

Description : What is the purpose of the 'annunciator module' (6000F35) shown in the illustration? EL-0094 A. Provide an input to the setpoint module. B. Drive the alarm lamp and, through the controller, the horn. ... and +24 volts to their respective power supplies. D. Connect 24 volts to both sides of the horn.

Last Answer : Answer: B

To insert a new slide in the current presentation, we can use ____key: a) Ctrl + M b) Ctrl + N c) Ctrl + O d) Ctrl + F e) None of The Above

Description : To insert a new slide in the current presentation, we can use ____key: a) Ctrl + M b) Ctrl + N c) Ctrl + O d) Ctrl + F e) None of The Above

Last Answer : a) Ctrl + M

Mention the factors on which the magnitude of the e.m.f induced in the transformer depends.

Description : Mention the factors on which the magnitude of the e.m.f induced in the transformer depends.

Last Answer : 1) E.m.f in the primary coil 2) Number of turns in the primary coil 3) Number of turns in the secondary coil 4) The core material