Electrical Engineering Interview Questions

      1.    Maximum Marks: 75

2.     Write or tick the correct answer (one or more) from the multiple choices.

3.     Duration of the test is 30 minutes.

4.     Each question carries different marks.

Name of the

Participant: _________________________________ Location: ________________

 Electrical Engineering Interview Questions

1.         What are the origins of Power Quality Problems? (3)

(a)   Mains Power from Utility company, (b) Mother Nature,

(c) Human Errors, (d) Office or Industrial Internal Environment, (e) All of the above

2.         What are the consequences of Power Quality Problems? (3)

(a)   Loss of Business, (b) Loss of valuable data,

(c) Dissatisfied customers, (d) Loss of Production, (e) Financial Losses, (f) None of the above

3.         List the Power Quality Problems (Events) that may affect your critical load. (3)

(a)   Over-voltage, (b) Under-voltage (c) Sags/Brownout, (d) Surges/Swells,

(e)  Voltage Spikes/Impulses/Transients, (f) EMI/RFI Noise, (g) Frequency Variations, (h) Waveform Distortion, (i) Mains Outage/Blackouts, (j) All of the above with different possibilities of occurrences.(h) None of above.

4.         Which are the most important interfaces the UPS has to be compatible with? (3)

(a) UPS and Critical Load capacity, (b) UPS and input power  
     source, (c) UPS and its physical environment around its installation,
     (d) All of the above.

5.         What are the generic features of UPS as a source of power? (3)

(a)Electronically synthesized & high quality power output, (b) Weak power source with  very limited overload and short circuit capability, (c) Can eliminate all your power problems, (d) All of the above.

6.         Which are the possible types of UPS configurations / technologies available for protection of your critical load? (3)

(a)   Off-line / Standby UPS, (b) Line-interactive, (c) On-line UPS, (d) All of the above.

7.         What are the features of On-Line UPS why it is preferred over other configuration? (3)

(a)   Provides highest level of power conditioning and backup protection, (b) Zero switchover times during mains outages, (c) Completely regenerated output power using double conversion technique, (d) Provides output frequency regulation, (e) 100% effectiveness of power protection, (f) Redundancy is possible, (g) Maintenance possible without load shutdown.

8.         List the most important specification parameters of an UPS? (3)

(a)      Load Capacity in kVA, (b) Load inrush current, (c) Battery backup time, (d) Allowable input voltage range, (e) Input current harmonics, (f) AC to AC efficiency.

9.         Draw the block schematic diagram of a UPS system to be installed at Surma Cement (4)

10.      How many power feeders are incoming at the UPS input? Give details. (3)

11.      What is the nominal output voltage, phase and frequency of UPS? (3)

12.      What type of batteries are installed with the UPS at Surma Cement? (2)

13.      How many number of Nickel Cadmium battery cells are connected in series for

    (a) 15 kVA UPS,                                     (b) 30 kVA UPS                               (2)

14.      What is the float charge voltage for batteries connected to                                    

   (a) 15 kVA UPS                                       (b) 30 kVA UPS                                      (2)

15.      How much is the battery back-up time with UPS on full load? (1)

16.      How many LEDs are seen on front panel mimic of                                                  

   (a) 15 kVA UPS                                        (b) 30 kVA UPS                                     (2)

17.      What must be done in case the UPS shows an audio visual Battery Discharging alarm? (2)

18.      What will happen if the batteries discharge fully and the inverter of the UPS stops due to low DC voltage. (2)

19.      What is the maintenance required for the Nickel Cadmium batteries installed? (2)

20.      What is the maintenance required for UPS? (3)

21.      What is the maintenance required for the Input Isolation Transformer cubicles? (2)

22.      What is the function of the Rectifier in the UPS (2)

23.      What is the function of the Battery charger in the UPS (2)

24.      What is the function of the Inverter in the UPS (2)

25.      What is the function of the Static Bypass in the UPS (2)

26.      What is the function of the Maintenance Bypass in the UPS (2)

27.      What will happen if a short circuit takes place anywhere in the UPS load distribution branches? (3)

28.      How much should be the voltage between the Earth and the UPS output Neutral terminal? (1)

29.      How much should be the voltage between the Earth and the UPS output Line terminal? (1)

30.      Which are the most critical alarms indicated by UPS on its front panel mimic? (3)

31.      What should be the routine log you must maintain for the UPS installation? (3)