392 Power System Questions and Answers

Explore 392+ Power System questions and answers covering power generation, transmission, distribution, protection systems, substations, fault analysis, power system operation, and electrical network fundamentals.

This collection includes technical questions related to:

Power Generation
Transmission Systems
Distribution Systems
Power System Protection
Switchgear
Substations
Fault Analysis
Load Flow Studies
Power System Stability
Circuit Breakers
Relays and Protection
Electrical Network Analysis
Power Quality
High Voltage Engineering

The questions cover power system fundamentals, electrical power transmission, fault calculations, protective relaying, network performance, system stability, voltage regulation, power quality issues, and practical engineering concepts commonly used in utility and industrial power systems.

These Power System questions are useful for engineering students, electrical engineers, technicians, competitive exam aspirants, and professionals preparing for technical interviews, university examinations, and power industry careers.

Browse the Power System questions below and strengthen your understanding of electrical power networks and modern power engineering technologies.

392 Power System Questions

S.No.	Power System Question
1	What are “Instrument Transformers”?
2	Which is not a protective system?
3	What are the properties of Vacuum Circuit Breaker?
4	What are the features of SF6 Circuit Breaker?
5	Faults on the overhead line in a 3-phase system, which has the ___
6	Which of the above mentioned “Faults” in the electrical system is wrong from reality?
7	Which is not the characteristic of faults in the power system?
8	Which type of relay is suitable for detecting Faults in high voltage power transmission systems?
9	Which distance relay is suitable for the protection of power lines that have a very long cable length?
10	Why must the zone of protections be divided into sections?
11	Which of the following relays Arranged in the ___
12	The distance Relay to be used to protect the transmission line has a ___
13	Setting the distance relay, Step Distance Protection, Relay Zone 3, will ___
14	Setting the distance relay, Step Distance Protection, Relay Zone 1 should be ___
15	One of the impedance relays has a circular motion ___
16	Reducing the risk of under-reach of distance relay can be ___
17	One transmission line has an impedance including a line of ___
18	One of the impedance relays has a circular motion, with a radius of ___
19	How does the Power System Swing affect the distance relay?
20	What are the characteristics of the Mho Relay distance relay function on the R-X diagram mode?
21	How does the fault resistance caused by arc affect Distance Relay?
22	How does Power System Swing affect distance relays?
23	Which of the following concerns the transmission line protection using Distance Relay?
24	“Lenticular Relay” has the following features ___
25	Protection of high voltage power lines using a three-zone protection distance relay
26	One line of transmission is 80 km long with the impedance ___
27	Which of the following relay Is the main relay used to protect the ___
28	“Quadrilateral Relay” is a suitable relay for use in which manner of protection ___
29	Which of the following are the impedance relay properties of the impedance relay?
30	The transmission line size 2.5 + j3.5 ohm must set the value of ___
31	When the Arc Fault occurs in the power transmission line ___
32	The setting for Phase Fault Distance Relay must use which ___
33	The impedance value is the value that the distance relay sees when knowing the ___
34	The high-voltage power line has an impedance per phase of 10 ohms, a 70-degree angle
35	High-voltage power lines have an impedance per phase of ___
36	Why do we use Distance Relay to protect high voltage power lines?
37	Reactance Relay (Reactance Relay) is a distance relay that will work when
38	What is distance relay’s Overreach?
39	What is Distance Relay Reach?
40	Which of the following distance relays is with features of direction?
41	Which of the following distance relays is with features of no direction?
42	When distance relay works?
43	Which type of relay is suitable for detecting Faults in ___
44	Which distance relay is suitable for the protection of power lines that have ___
45	Using distance relay (Distance Relay) to protect power lines ___
46	Impedance Relay is suitable for preventing short-circuit between the ___
47	Which of the following relays Arranged in the Distance Relays group
48	Relay The distance to be used to protect the transmission line has a ___
49	Setting the distance relay, Step Distance Protection, Relay Zone 3, will have to ___
50	Setting the distance relay, Step Distance Protection, Relay Zone 2 will have to ___
51	Setting the distance relay, Step Distance Protection, Relay Zone 2 should be set to ___
52	Setting the distance relay, Step Distance Protection, Relay Zone 1 should be set ___
53	Setting the distance relay, Step Distance Protection, Relay Zone 1, what is the working time setting?
54	What is the feature of the Mho Relay feature?
55	Which is the feature of the Impedance Relay?
56	In the Ground Fault Distance Relay setting for protection, when a single line to ___
57	Analysis of the operation of the ___
58	Input signal to distance relay ___
59	In High voltage power transmission protection, in general what type of relay is ___
60	Ground Directional Overcurrent Relay can use Which quantity to ___
61	Over current relays Extremely Inverse (EI) [IEC 60255] by setting ___
62	If you want to make Earth Fault Protection with Overcurrent ___
63	The Radial System distribution system, as shown, requires both relays to have ___
64	The Radial System distribution system, as shown, requires both ___
65	The Radial System distribution system, as shown, requires both relays have an ___
66	Radial distribution system shown below requiring both relays have a ___
67	How to use the Residual Current as a Polarizing Signal to detect ___
68	Ground Directional Overcurrent Relay, when Single Line to ___
69	Phase directional overcurrent relay of 90-degree connection type ___
70	Overcurrent Relay has a Curve of Long Time Inverse (LTI) in accordance with ___
71	Standard Inverse Overcurrent Relay is compatible with ___
72	Phase Directional Overcurrent Relay Type Electromechanical type ___
73	Protection of Earth Fault Protection in a 3-phase power system with ___
74	Standard Inverse Overcurrent Relay connected to the current transformer ___
75	Standard Inverse Overcurrent Relay connected to the current transformer (CT) with ___
76	Electromechanical phase directional overcurrent relay type ___
77	Phase Directional Overcurrent Relay with 90-degree connection when considering ___
78	Phase Directional Overcurrent Relay with 60-degree connection, when considering only ___
79	What are the characteristics of over current relays? Popular today
80	Extremely Inverse Overcurrent Relay is set as follows ___
81	Over current relays with Standard Inverse (SI) Curve operation ___
82	Over current relays with Very Inverse operation (VI) [IEC 60255] by ___
83	Discrimination What is the current overload protection system?
84	Phase Directional Overcurrent Relay with 90-degree connection â€“ MTA is 45 degrees at ___
85	Over current relays with Very Inverse operation (VI) [IEC 60255] by setting TMS to ___
86	Over current relays have a Standard Inverse operation (SI) [IEC 60255] with a ___
87	Very Inverse Overcurrent Relay has the following settings ___
88	What is the current overload protection Discrimination system?
89	Phase Directional Overcurrent Relay with 90-degree connection-45 degrees MTA ___
90	Which is not the Directional Overcurrent Relay working condition?
91	Which of the following Can be used as a Polarizing Quantity of Directional Overcurrent Relay?
92	Which of the mentioned use of Overcurrent Relay is wrong?
93	In any of the following cases, the Overcurrent Relay used for ___
94	Overcurrent Relay, connected to circuit through the current transformer (CT) with ratio ___
95	What is Grading Margin?
96	What is Time Multiplier Setting (TMS)?
97	What is Plug Setting Multiplier (PSM)?
98	Which of the following devices do Not need Directional Overcurrent protection?
99	Dual Polarizing Earth-Fault Relay fault protection relay is not intended to ___
100	To adjust the current setting of the Overcurrent Relay, it must be adjusted at ___
101	High Setting Instantaneous Overcurrent protection device’s number relay is ___
102	Earth Fault Protection of 3-phase generators that are grounded by ___
103	In the 3-phase 3-wire electrical system, Earth Fault Protection with the ___
104	Overcurrent Relay, connected to circuit through the ___
105	Overcurrent Relay, connected to circuit through the current transformer (CT) with ___
106	Overcurrent Relay, connected to circuit through current transformer ___
107	Polarizing Quantity of Directional Overcurrent Relays define as ___
108	Phase Directional Overcurrent Relay (67) For ___
109	Directional Overcurrent Relay, which amount is ___
110	Directional Overcurrent Relay can use which quantity as a Polarizing Quantity
111	Phase Directional Overcurrent Relay What kind of connection can be used?
112	Phase Directional Overcurrent Relay and Ground Directional Overcurrent Relay ___
113	What are the working conditions of Directional Overcurrent Relay?
114	One power system has a maximum short circuit current of ___
115	What are the meanings of “overcurrent” in electrical protection?
116	Which is not an important factor in determining the time value of grading margins for ___
117	Grading Margin depends on which of the following ___
118	Directional overload relay detects Faults by ___
119	What is the characteristic of the Inverse Time Overcurrent Relay?
120	What are the characteristics of the definite current overcurrent relay overcurrent relay?
121	What are the characteristics of the definite time overcurrent relay over current relay?
122	Discrimination Of the relay in the overcurrent protection system Which method is use?
123	Equipment code number 25 in accordance with ANSI Standard, means ___
124	According to the IEC 60617 (IEC Relay Symbols) symbol of relay as ___
125	The principle of harmonic detection in relays with is ___
126	Which of the following relay groups operational with CT only?
127	Which of the following relay groups operational with VT only?
128	Which of the following codes and device names are incorrect?
129	Which of the following codes and device names are all correct?
130	Which of the following codes and device names are all right?
131	From the following message Which is correct?
132	Incomplete Sequence Relay (48) is ___
133	Which of the following relay groups Must be used with both CT and VT measuring devices?
134	Within the structure of the relay model Microprocessor or Digital Relays that are ___
135	The principle of Relaying Pilot is ___
136	Over Load Relay with Bimetal, how does it work?
137	Which of the following relays have Adjustable Logic Elements?
138	The mechanism of digital relays ___
139	Which of the following relays Relying on the current stimulation that comes from ___
140	Which of the following relays uses Impedance as a Pick-up quantity?
141	According to IEC 60617 (IEC Relay Symbols) symbol of relay shown below ___
142	According to IEC 60617 (IEC Relay Symbols) symbol below means ___
143	According to IEC 60617 (IEC Relay Symbols) symbol of relay as shown below means ___
144	According to IEC 60617 (IEC Relay Symbols) symbol of relay as shown means ___
145	According to IEC 60617 (IEC Relay Symbols) symbol of relay as shown What device does it mean?
146	According to IEC 60617 (IEC Relay Symbols) symbol ___
147	According to IEC 60617 (IEC Relay Symbols) symbol of ___
148	From the following message Which is correct
149	Which is not the difference between Instantaneous Relay and ___
150	Under-Voltage Relay will operate when the voltage is lower than ___
151	Device code 52-b according to ANSI Standard means ___
152	Device ID number 52-a according to ANSI Standard it means ___
153	Which of the following types of relays uses Impedance Pick up to allow relay to operate?
154	If you analyze evolution of Relays from the past to the ___
155	Number 81 relay according to ANSI Standard means what kind of ___
156	Which of the following technique is not used to detect Earth Fault with Overcurrent Relay?
157	Directional Power Relay (32) used in any of the following cases __
158	Equipment used to analyze and process signals in ___
159	The main function of Relays is ___
160	When will the Over-Voltage Relay connect to the “a” type?
161	ANSI Standard Number 21N relays refer to which type of ___
162	Relay number 47 in accordance with ANSI Standard means ___
163	Relay number 46 according to ANSI Standard means which relay?
164	Pressure Relay is used to protect which of the following devicesp
165	Which quantities Voltage Restraint Overcurrent Relay Uses?
166	Faults detection principle of relays in general, In an electrical systems with ___
167	Voltage Relay cannot be used ___
168	Purpose of current transformers (CT) to detect Zero-Sequence is ___
169	You have Electro-mechanical relay, and you want to use ___
170	Which of the following device is not the basic equipment for the protection of power system?
171	What are the main equipments used to protect the electrical system?
172	What type of relay is High Impedance Relay?
173	What is the Fault Detection principle of the relay?
174	Number 49 relay according to ANSI Standard represents ___
175	Number 67 relay according to ANSI Standard represents ___
176	Number 51 relay according to ANSI Standard represents ___
177	Number 50 relay according to ANSI Standard represents ___
178	Number 21 relay according to ANSI Standard represents ___
179	Number 87 relay according to ANSI Standard represents ___
180	Which of the following types of relays Based on the principle of ___
181	Which is not a feature of Digital Relay
182	Which of the following mentioned statement about Electromagnetic Relays is wrong?
183	Which of the following types of relays detect faults by using ___
184	Which quantity from mention below quantities to be compared for phase angle comparison
185	Which of the following relays uses the Faults detection method in the ___
186	Which of the following not related to Distance Relay?
187	What is the pick-up value of the relay?
188	Under Voltage Relay uses the method of detecting faults ___
189	We have Non-Directional Overcurrent Relay, how we will ___
190	According to IEC 60617 (IEC Relay Symbols) symbol of relay as ___
191	Which is not the method of detecting faults in the relay power system?
192	Relay number 50 (Relay Device Number 50) What is a relay?
193	If we want to protect our feeder from excess of ___
194	If we want to protect our feeder from excess of current more than ___
195	Overload and Overcurrent Protection Relays are same in ___
196	Which of trip supervisory scheme have Scada features?
197	This is Trip circuit ___
198	This is Trip circuit supervisory ___
199	This is Trip circuit supervisory scheme ___
200	This figure represents ___
201	This diagram represents ___
202	This is figure represents ___
203	In Transmission system, solidly earthed, RCA in ___
204	In distribution system, solidly earthed, RCA in Directional EF Relay is
205	In resistance earth system, RCA in Directional EF Relay is ___
206	We have 90° – 45° connection Directional overcurrent ___
207	This is ___
208	Choose the correct option
209	Choose the correct answer for the table ___
210	Find the correct one ___
211	Find the correct answer ___
212	Directional block is ___
213	The angle between the polarized value and measured value of ___
214	In 90° – 45° connection, what is MTA?
215	In 90° – 30° connection, The relay sensitivity at unity power factor is ___
216	In 90° – 45°, Relay sensitivity is maximum when the current lags the ___
217	In 90° – 45°, This connection gives a correct directional tripping zone over the ___
218	What you are analyzing from this graph?
219	In 90° – 30°, Relay sensitivity is maximum when the current lags the ___
220	Current range of ___
221	This directional relay has following ___
222	This directional relay has ___
223	Input source/sources of Directional ___
224	Input source/sources of Directional OC relay ___
225	Directional relay has ___
226	Directional Relay are designed to operate for ___
227	Choose the appropriate answer ___
228	Find the answers with the help of the figure below ___
229	The earth fault magnitude is ___
230	What is knee point voltage at 800:1 ratio?
231	How many phases we are testing in this setup?
232	Time interval between primary and back up relay is ___
233	The tripping time of Back up relay is less then ___
234	I want to test OC pick up of the relay associate with mention below ___
235	What is OC relay setting for Short circuit current for TMS=0.100?
236	What will be the EF-Tripping Time of 33KV outgoing feeder, if 1 XFmer is connected?
237	What will be the EF-Tripping Time of 33KV PMR at Gantry, if 2 XFmer is connected?
238	What will be the OC-tripping time of 33KV Xfmer incomer pick up 1 A?
239	What will be the OC-tripping time of 33KV bus coupler?
240	What will be the OC-tripping time of 33KV Outgoing feeder with 1 XFmer?
241	What will be the OC-tripping time of 33KV Outgoing feeder with 2 XFmer?
242	What will be the OC-tripping time of 33KV PMR at Gantry with 1 XFmer?
243	What will be the OC-tripping time of 33KV PMR at Gantry with 2 XFmer?
244	If 114-114B is closed and all remaining contacts (112-112B and 113-113B) are ___
245	If 113-113B is off and all remaining contacts (112-112B and 114-114B) are off ___
246	As per this diagram, what ratio we are using of multi-ratio CT?
247	If we want to use 400:1 from this multi ratio CT, the secondary contacts will be ___
248	If we want to use 800:1 from this multi ratio CT, the secondary contacts will be ___
249	If we want to use 1200:1 from this multi ratio CT, the ___
250	What will be the position of Test block’s contacts 21-22,23-24,25-26 and ___
251	We want to Test 3 phase to ground faults, where we will inject currents?
252	We want to Test 3 phase faults, where we will inject currents?
253	If I want to Test C phase to Ground fault, from which points of test block we will inject pick up current?
254	If I want to Test B phase to Ground fault, from which points of ___
255	If I want to Test A phase to Ground fault, from which points of test block we ___
256	The Relay send trip signal to breaker without delay is ___
257	NO contact remains ___ during normal condition
258	In this circuit arrangement, what we are testing?
259	Here PSM =
260	What is the 5-13-9 represnts ___
261	Normally close contact remains close during normal condition
262	16-18 is denoting in the figure below is ___
263	What is R in this Figure?
264	In the figure, which relay is it?
265	In the figure, what 96 defining in this figure?
266	What does 67N is representing?
267	What 74 defining in this figure?
268	Minimum value of current at which relay operate is ___
269	If OC TCC is SI, TMS=0.1, Relay pick up is 2, what is tripping time?
270	If OC TCC is SI, TMS=0.1, Relay pick up is 1.1, what is tripping time?
271	In Extreme Inverse time current characteristics, tripping time is ___
272	In Standard Inverse time current characteristics, tripping time is ___
273	In Very Inverse time current characteristics, tripping time is ___
274	This characteristic belongs to the which relay?
275	The multiple of passing current is ___
276	Minimum time required by relay to operate is ___
277	This characteristic belongs to which relay?
278	Let us consider an 33/0.4 KV auxiliary/earthing transformer with ___
279	Please see the shown figure and inform us which type of battery system is this?
280	Please see the below figure and inform us which type of battery system is this?
281	Please see the figure and inform us which type of battery system is this?
282	Normal Battery bank voltages are ___
283	All auxiliary supply in substation are ___
284	Low Voltage AC supply for the substation control and ___
285	What is knee point voltage of CT B?
286	What is Knee point Voltage of CT A?
287	We have Delta-star 630KVA Transformer, 33/11KV, impedance is 5%, please select ___
288	DC component of CT is due to ___
289	Number representing the amount by which current increase from ___
290	During Testing of Short thermal Current of CT, Secondary of ___
291	During Testing of Dynamic Current of CT, Secondary of CT will ___
292	The Peak value of the primary current at which CT will ___
293	The RMS value of the primary current at which CT will withstand for ___
294	What is the correct answer to the question represented in the images?
295	What is the Value of R4 CT in the below?
296	What is the Value of R4 CT?
297	Please see this arrangement and inform what test we are conducting?
298	Please see this arrangement and inform us what test we are conducting?
299	In Polarity Test, when we inject current and result on ___
300	In Polarity Test, when we inject current and result on high range ammeter is ___
301	Please see this circuit and inform us what test we are conducting?
302	In Which CT we will place high range Ammeter in series CT Ratio Test by Primary injection method?
303	Why we are short circuiting the poprimary of CT in CT Ratio Test by Primary injection method?
304	How much current we will inject in CT, while conducting Ratio Test by Primary injection method?
305	Please see this, and inform us which test we are conducting?
306	Which one is most safe way to measure current across CT’s secondary during CT Secondary injection?
307	In this injection what will be the position of our Test Block?
308	Where we are analyzing these results?
309	Fill in the blanks ___
310	Please see attached, and inform what we are doing?
311	Which Test is it?
312	In Insulation Resistance Testing, if we are Testing Marked connection ___
313	In Insulation Resistance Testing, if we are Testing Marked connection of ___
314	IF CT polarity is ok, then Deflection in Ammeter will be ___
315	In Polarity Test, Positive Terminal of Battery is ___
316	How much error is acceptable in CT Ratio Test?
317	What will be the value of current injection in CT Ratio Test?
318	For Polarity Test of CT, battery rating will be ___
319	For polarity Test of CT, we will use ___
320	The CT below is ___
321	Please see the figure and inform what is the connection below?
322	Please see the figure and inform what we are doing below?
323	Please see the figure and inform what we are doing?
324	Please see figure and inform what we are doing?
325	Which wire connection for CT is correct?
326	What is the value of Dynamic Current?
327	The knee point voltage in the below is ___
328	We have 600:1, 5P10,15VA CT, what will be the Knee point Voltage?
329	CT connected burden is 1.8ð›º, Impedance of the CT Winding is ___
330	We have 3-phase multi-ratio CT with 400, 800, 1000, 1200/5, if we are using ___
331	We have 3-phase multi-ratio CT with 400, 800, 1000, 1200/5, if we are ___
332	We have CT 10P10, what is it defines?
333	We have 400:5 CT, connected with 3ð›º Relay, lead resistance is ___
334	We have 400:1 CT, connected with 3ð›º Relay, lead resistance is ___
335	CT’s Secondary currents are ___
336	Power Factor is ___
337	Saturation help in protecting connected burdens ___
338	Knee point of metering CT is more then Knee point of ___
339	Accuracy classes of Protection of CT is ___
340	If you have 5P20, 300:5, 15VA CT, find ___
341	If you have 5P20, 300:1, 15VA CT, find Maximum Allowed primary current ___
342	S.I. Unit of Burden is ___
343	S.I. Unit of Remanence is ___
344	Load connected to the secondary of CT is ___
345	One method to determine knee point on the curve as described by ___
346	Accuracy limit factor is ___
347	At knee Point, CT will be ___
348	When CT saturates, it ___
349	___ mains in CT, until primary current reapplied
350	When CT’s primary current stopped to flow, the amount of ___
351	For testing purpose, CT knee point is defined as ___
352	Knee point is point at which ___
353	CT’s excitation current increases, When ___
354	Excitation current in CT will produce flux, which then induce
355	The main property of good CT core is that
356	What is the CT connection below?
357	What is the CT connection here?
358	Which CT/CTs is/are connected in circuit with correct Polarity?
359	Which of below given CTs is with correct polarity?
360	If primary current flow from P1 to P2, and if CT polarity is ___
361	What will be ratio of connected Combined CTs?
362	What will be the ratio of connected Combined CTs?
363	If Number of Primary Turn is 2, secondary number of turns is ___
364	If Number of Primary Turn is 2, secondary number of turns is 100, what is CT Ratio?
365	If Number of Primary Turn is 1, secondary number of turns is 100, what is CT Ratio?
366	In this Multi Core Ratio CT, if we are using ratio 200:1, What will be the ___
367	Which one is Multi Core CT?
368	In this Dual Ratio CT, if we are using ratio 200:1, What will be the position of ___
369	Which one is Dual Ratio CT?
370	Which one is CT representation?
371	Primary conductor of CT should have very low ___
372	Eddy current in CT reduce when Permeability of CT is ___
373	Ring CTs are Prefer to use on ___
374	Which is Wound Type CT?
375	Which one is Bar CT?
376	CT Ratio is 1000:1, excitation current is 25mA, what is ratio error?
377	CT Ratio is 1200:1, excitation current is 30mA, what is ratio error?
378	Magnetic or excitation current is high in system, one of the reasons is ___
379	Primary Current ð¼ð‘ƒ of Current Transformer =
380	Current Transformer is ___
381	Flux of Primary current in Current Transformer, induces voltage in ___
382	Current Transformer is Transformer which has ___
383	The Drop out current of Relay is ___
384	The Pick up current of Relay is ___
385	What is the secondary standard Voltage of ___
386	Which terms describe the meaning of the device “CCVT” correctly
387	“CCVT” stands for what?
388	“Rated Burden” of the current transformer (CT) means ___
389	Which is not the function of the current transformer (CT)?
390	Current transformer transformers (CT), the size of the Burden 15 VA with a ___
391	Standard secondary current of current transformer for the ___
392	About the Power System MCQ category