16 Interview questions for Oil & Gas electrical engineering Jobseekers

1. What is the classification of hazardous area?

Hazardous areas are classified into different Zones:

Zone 0: an explosive gas-air mixture is present continuously or for long period.

Zone 1 : Explosive gas-air mixture is present in normal condition

Zone 2 : Explosive gas-air mixture presents only for a short time.

2. What is the definition of EExd IIB T5?

Exd: Explosion proof

II b : Gas group

T5: Temperature 1000°C

3. Explain what is IP 54, IP 55 etc:?

According to the electrical standards IP means the degree of protection of enclosures for electrical equipments. The number following the alphabets IP denotes degree protection against liquid and solid bodies.

First number denotes the protection against solid bodies (dust, harmful deposits)

Second number denotes the protection against the liquid.

4. What is the gas group classification?

  • Methane I
  • Propane IIA
  • Ethylene IIB
  • Acetylene IIC
  • Hydrogen, Carbon

5. What is AVO meter?

AVO meter (Ampere, Volt, Ohm meter) is used to measuring the electrical circuit and the value of current, voltage and resistance is called AVO meter.

6. What are the different size of cables?

0.75, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300, 400, 600 (Dimensions are in Square mm)

7. What are the Cables used in Oil Field?

PVC - Ploy Vinyl Chloride

XLPE - Cross Linked Poly Ethylene

LC - Lead covered

SWA - Steel wire armoured

PILC - Paper Insulated Lead Covered Cable

MICC - Mineral Insulated Copper Conductor

8. Why Lead Covered Cables are used in Oil Fields?

Lead Covered Cables are used in Oil Fields to avoid hydrocarbon gas and chemical corrosion damage to PVC isolation.

9. How to check the fault in a cable?

The test used to check the cable is Megger test: A Megger test or sheath resistance test is used to diagnose cable faults, either short circuit problem, water penetration, moisture or current leakage. A Megohmmeter is used to measure the resistance of the crossed-link to an applied DC voltage.

10. What is cable gland? what type of cable glands are used in oil field?

Cable glands are used to protect against mechanical damage, to provide continuity to the earth and to enter the junction box, MCC, etc.

To avoid gasses from entering electrical equipments “Double compression glands” are used in explosion proof areas.

11. Why the battery room is normally considered for Hazardous area classification?

Because of Hydrogen evolution and it will come under gas group II C

12. What is use of Clip-on-meter?

In other words, the Tong Tester is called as a clip on a meter. In this, if noticed, we can measure the current flowing in the circuit for any unbalance in each phase. Can be used without the circuit breaking.

13. What are the light fittings used in Gathering Centers & Booster Stations?

Incandescent lamp, high-discharge mercury lamp, fluorescent lamp and halogen lamp fittings are used and certified by BASEEFA at Gathering Centers & Booster Stations.

14. What is stroboscopic effect? How can you eliminate it?

In the twin tube light set while the lamp glows, the ring moves one by one inside the florescent tube, which is called the stroboscopic effect due to the connection of two chokes nearby.

15. How can you find a motor is good with using of Multimeter & Megger?

The following value should be met for good motor:

  • Insulation resistance value should be appropriate by using the Multimeter between winding to earth
  • Winding resistance value should be equal on three windings

16. What is Bridge Megger? Where it is used?

Bridge Megger is used to accurately measure the lowest resistance level and is used during preventive maintenance to measure the winding resistance of the motor and the winding resistance of the transformer.