Electrician interview - There are questions and answers related to circuit breaker. Which are mostly asked in interviews. Hope this helps you.

Question 1- What is a circuit breaker?

Answer 1 - Circuit breaker is a mechanical device. Which closes and opens the electrical circuit in normal and abnormal state.

 Question 2 - Which type of circuit breaker?

Answer 2-

1 - Air Circuit Breaker (ACB)

2 - Oil Circuit Breaker (OCB)

3 - Vacuum Circuit Breaker (VCB)

4 - Air Blast Circuit Breaker (ABCB)

5 - SF6 Circuit Breaker

Question 3- How does air circuit breaker work.

Answer 3 - Air circuit breaker is used for law voltage. Occur in abnormal condition or at the time of make and break. The electric arc generated is extinguished with the help of arc chute from normal air. The breaker is accompanied by a protection relay that disconnects the electric circuit from the supply at fault time. It is used for power distribution in PCC panel.

Question 4 - What is the difference between switch and circuit breaker?

Answer 4 - The switch is a device which only opens and closes the circuit in normal condition. The circuit breaker operates in both normal and abnormal state. Can sustain high current during fault time. The circuit breaker can also be operated from the control panel.

Question 5- What is the meaning of making capacity in circuit breaker?

Answer 5- When the circuit breaker is closed then the first kick of the current is called the making capacity of the breaker. The passing during a short circuit is considered to be current. Its value is in KA.

Question 6- How does a vacuum circuit breaker work?

Answer 6 - Vacuum circuit breakers are used for medium voltage from 6.6kv to 33 kv. It uses vacuum to extinguish the electric arc. Vacuum does not contain oxygen, hence spark is not generated. Vacuum pressure is 10-6 torr. Protective relay is mounted on the control panel. Which provides protection to the circuit in an abnormal state.

Electrician interview - There are questions and answers related to circuit breaker. Which are mostly asked in interviews. Hope this helps you.

Question 7- What is the meaning of breaking capacity in a circuit breaker?

Answer 7- The breaking capacity in a circuit breaker is in KA. Breaking capacity of the breaker at the time of fault is called breaking capacity. Which is also called maximum rms value.

Question 8- Which metal is used in VCB contact?

Answer 8- The VCB contact uses silver lead, silver bismuth, copper lead, copper tellurium, metal. Above the contact is the silver lead and silver Telurium.

Question 9- How does SF6 circuit breaker work.

Answer 9- EHV - Used in the supply line from 33 kv to 760 kv. The electric arc in the make and break is quenched with SF6 (sulfur hexa fluoride) gas. In the normal condition, the pressure of SF6 is 6.2 kg / cm 2. This pressure is 14 to 17 kg / cm 2 at the time of operation. They are in both indoor and out door type. Protection relay control panel is installed which provides protection to the electric circuit.

Question 10 - AC circuit breaker is suitable for D.C supply?

Answer 10- Generally AC circuit breakers are not suitable for DC supply. The electric arc is easily extinguished when there is zero in the alternating wave. Where there is no existence of wave in DC, therefore, the value of current is not zero.

Question 11- How does air blast circuit breaker work?

Answer 11- ABCB is used for medium and high voltage (22 kv to 220 kv). In this breaker, the arcs arising at the time of make and break are extinguished by the blast of air. In this, air is compressed and stored in the tank. And the nozzle is used to extinguish sparks at great speed. In any unusual situation, there is a protective relay for protection. Which protects the circuit.

Electrician interview - There are questions and answers related to circuit breaker. Which are mostly asked in interviews. Hope this helps you.

Question 12- How is the selection of circuit breaker done?

Answer 12 -

1 - How much ampere is our constant load. It should be 25% higher capacity breaker.

2 - How many poles need a breaker, this has to be done. It consists of 3P and 4P.

3 - The voltage capacity of the breaker should be constant.

4 - Interrupting capacity should decide which is in mva and ka.

5 - Supply frequency and making capacity of the breaker should go ahead with the offer.

Question 13 - How much is the breaker voltage compared to the line voltage in HT line?

Answer 13 - For a 6.6 kv in HT line, let's select a breaker of 7.2 kv. There are 12 for 11 kv. 36 kv remains for 33 kv. A breaker of 145 kv is used for 72 kv and 132 kv for 66 kv. Certainly the capacitance of the breaker will be more than the line voltage.

Question 14- How different circuit breakers are named.

Answer 14 - The function of circuit breaker is to extinguish the electric arc occurring at the time of make and break. The media used to extinguish this electric arc has its name on its base. For example, a vacuum circuit breaker uses vacuum to extinguish the arc. And oil is used in oil circuit breakers.

Question 15- How do oil circuit breakers work?

Answer 15 - Oil circuit breaker is used for medium voltage. In this breaker, electric arc arising at the time of fault or at operation is extinguished with oil. The contact of the breaker is immersed in the oil. There are two main functions of oil in it. Acts as an insulator between a contact. Second, when the spark occurs, the heat generated cools quickly. In other words, it also works for cooling. Protection relay is mounted on the control panel. Which protects the circuit.

Question 16- What is the relay setting in air circuit breaker?

Answer-16

ir - Over load setting - This setting is set based on our constant running load. By the way, setting the maximum breaker capacity to 90% is considered correct.

isd - short circuit - The setting of the short circuit is based on the over load setting. The winning setting is done four times more than it loads. In other words, if the overload setting is 1000 amperes, then the short circuit setting is 4000 amperes.

ig - ground fault - usually set at 40% of the capacity of the pay breaker.

All three of the above (ir, isd, ig) have settings along with time setting.

ii - Instantaneous Current - As much as the current is set there, the breaker will be tripped immediately. There is no time setting in this.

Question 17 - What is the Anti Pumping contactor in the breaker?

Answer 17 - Anti Pumping Contactor is in every breaker. Its main function is that the breaker does not get the closing command once after the closing command. Therefore, anti-pumping contactors are used.

If there is a fault in the line The breaker will be tripped as soon as it closes. In such a situation, the operator presses the push button and the breaker will get the command of closing again after tripping. And if it repeats, it damages the breaker. Therefore, anti-pumping contactor is applied.

Question 18 - What is MCCB? How does it work?

Answer 18 - Full Form of MCCB - Module Case Circuit is Breaker. MCCB

He is the most commonly used circuit breaker in industries. 125 Amp. It has a rating of 800 ampere. And is used in low voltages 120 Used up to 450 volts. There are two types of MCCB available, one is thermal base protection and the other is microprocessor base protection. MCCB has protection like overload, short circuit, earth fault. Which we can set according to our requirement.

Question 19 - what is the difference between fuse and circuit breaker?

Answer 19 -

Fuse - The fuse has a wire according to its capacity. Which melts when the temperature increases due to over load and short circuit. Once the element of the fuse is blown, it is not used again. The fuse itself is replaced.

Circuit Breaker - The circuit breaker consists of a bimetal strip. Which breaks the circuit at the time of over current and short circuit. It can be reset and turned on.

Electrician interview - There are questions and answers related to circuit breaker. Which are mostly asked in interviews. Hope this helps you.

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Mechanical Technician Interview Question & Answers

Question 1- How many type of gaskets are there?

Answer 1- There are different types of gaskets such as metallic gaskets, rubber gaskets, compressed asbestos fiber field gaskets, teflon gaskets, graphite gaskets, impregnated gaskets, ring type joint gaskets and graph oil gaskets. Which is used according to our request. 

Question 2- How many type of valves are there?

Answer 2- Ball Valve, Glob Valve, Needle Valve, Plug Valve, Diaphragm Valve, Gate Valve, Butterfly Valve, Non Return Valve, Boat Valve, Knife Edge Valve, Drain Valve, Pitch Valve, Pen Stack Valve, Flush Bottom Valve, etc. The type of valve is and this is selected according to our needs. 

Question 3- Which parts of the valve are there? What is his job?

Answer 3- Valve parts have different parts in different valves. Ball valve - The most important part in this valve is the ball. This is followed by parts such as valve body, end piece, seal follower, stem, seal, seat lock nut, handle gland packing, gland flange gland studs and nuts.

Gate Valve - This valve has parts like gate, seat body, stem, bonnet, gland flanges, hand wheels, gland bush, additionally gland nuts and bolts.

Globe Valve - This valve has parts such as plug, stem, hand wheel, body, bonnet, seat, lock nut, gland packing, gland flange gland studs and nuts.

Butterfly - This valve consists of body, stem, disc, seat, gland bush, ring holder, gland packing, bush, end cover, hand wheel or gear box, gland flange gland stud and nuts. 

Question 4- What is a valve called?

Answer 4- Valve is a device to control the flow of process. Which has auto and manual operating valves. And this is available in different types of recommendations for our needs.

Question 5- What is a gasket? And where is it used?

Answer 5- The work of gaskets is important. It works on the sealing member between two flanges. Which is placed in the middle of each flange.

• CAF - Gaskets are used in water line, gas line and air line.

• RTJ-bearing type joint gaskets are used in high pressure line.

• Rubber gaskets and Teflon gaskets are used in the chemical line.

Semi-metallic, metallic and graphite gaskets are used in the line of steam. Additionally, impregnated, valve sealing and spiral wound gaskets are also used in the steam line. 

Question 6- What is a flag? Where is it used?

Answer 6- Flanges work to connect two lines. Different lines are used in industries. Such as steam line, gas line, water line, chemical line, flanges are used to connect this type of line. 

Question 7 - What type of flanges are there?

Answer 7- Different types of flanges such as blind flange, sped flange, spectral flange, thread type flange, slip on flange, modifield flange, weld nose flange, goose nose flange, socket weld flange and stepped flange are fitted according to their requirement Hey 

Mechanical Technician Interview Question & Answers

Question 8- What is Gland Packing? Where is it used?

Answer 8- The packing that seals between two moving parts or two fixed parts is called Gland packing. It is used to prevent leakage in different shaft and line.

Question 9- What is the type of gland packing?

Answer 9-

• Teflon Gland Packing
• Carbon Gland Packing
• graphite gland packing
• graph oil gland packing
• Virgin PTFE Gland Packing 

Question 10- What is PRV and PSV?

Answer 10- PRV's full form is Pressure Relief Valve which releases the pressure. This valve has a set point. According to our needs, we can set the pressure in it. If the pressure is set to over, then these valves operate.

PSV - Full Form Pressure Safety Valve This valve is used for safety. These valves operate in such a situation that the pressure increases more than the set point to protect the device. 

Question 11- What is the name of the part of PSV?

Answer 11- In PSV its body, bonnet, nozzle, stem, blow down ring, blow down ring lock screw, disc, disc holder. There are parts like spring bottom plate, spring top plate, spring, gasket cap lock nut control screw.

Question 12- The use of Spade, Spectacle and blind is called?

Answer 12- Spade makes space between two flanges. And spreads the flow.

Spectacle - The use of both spade and blind in the same flange is called spectacle.

Blind - This is used to tie the line. Blinds in the middle of the line bind the flow in the line.

Question 13- What is a work permit in industries?

Answer 13- Before starting any work in industries, one has to take the permission of the related department. Permission is taken to allow that work permit to be charged by the safety officer, the worker and the plant in which he works. This entire process is called a work permit.

There are two types of work permits.

1 - Cold Work Permit - A cold work permit is made for work that cannot spark.

2 - Hot work permit - Where there is a possibility of spark from working, it is called hot work permit. Such as hot work permits for welding, cutting, grinding etc. 

Question 14- What is a heat Exchanger?

Answer 14- The job of heat exchanger is to exchange heat according to its name. Heating exchanges from heating to heating and cooling is called heat exchanger.

Mechanical Technician Interview Question & Answers

Question 15- What are the types of heat exchangers?

Answer 15 - Type

• fixed tube heat exchanger

• Yu Tube exchanger

• floating tube heat exchanger

• Bridge lock exchanger

• Plate type exchanger

• Fin Fan Cooler Exchanger

Question 16- What is the shell testing in the valve?

Answer 16- Flanges are fixed from both the sides while testing. The valve is opened and pressure is given from one side as required. And leakage is checked. The valve body, bonnet sealing area, and gland packing undergo a leakage test known as shell testing.

Question 17- What is seat testing in the valve?

Answer 17- Testing flanges are placed on one side of the valve. In total close condition, the valve is pressurized according to the standard. Leakage is checked in the seat and its opposite side. A similar step is not required to check the second seat of the valve except the globe and butterfly valves.

Question 18- Which medium is used for seat and shell testing?

Answer 18- Leakage check is done in seat and shell testing. Voters, D.M voters, air, kerosen and soap water are used for that testing

Question 19- What is meant by steam trap and gas trap?

Answer 19- Every industry that uses steam and gas has such traps.

• Steam strap is applied to a portion of the water from the steam.

• The gas strap is applied to remove part of the water from the gas. 

Question 20- What is the use of ejector?

Answer 20- Different processes take place in industries. Some air is required, some vacuum is required. Air meets Compressor. But creates a vacuum ejector for the process. That is why it is also called vacuum ejector. 

Question 21- What are non sparking tools? And where is the use?

Answer 21- Non sparking tools are those which are not likely to cause any kind of spark. Usually these types of tools are used in the gas oil and chemical industries.

Non-sparking tools use rubber hammer, nylon hammer, brass chisel, brass road, brass hammer, brass spanner, copper hammer, vigere tool, for example. 

Question 22- What is a strainer?

Answer 22- Strainer collects dust. The dust collected from liquids collects it is called strainer. It is cleaned at intervals.

Question 23- What is PPE? Name her?

Answer 23- Full form of PPE - Personal protective equipment’s. Those who use security devices to protect themselves are called PPE.

For example - tools like helmets, boiler shoots, safety goggles, noise plugs, safety shoes, gloves, dust masks are called PPE.

Mechanical Technician Interview Question & Answers

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Instrumentation Interview Questions and Answers

Q-1 - Which parameters are variable in the process?

Answer - Process has variable parameters.

1 - Pressure

2 - Flow

3 - Temperature

4 - Quality

5 - Level

Q-2 - Which equipment is used for flow measurement?

Answer- For flow measurement

1 - Venturi Tube

2 - Orifice Plate

3 - Pilot Tube

4 - News

5-flow nozzle

Q-3 - Which type of orifice plate?

Answer- There are four main types of orifice plate

1 - Segmental

2 - Concentric

3 - Quadrant Age

4 – Accentric

Q-4 - How will we know if there is an Orifice plate in the pipeline?

Answer-

There is an orifice tab, which welds with the orifice plate. Due to which the outer becomes thicker. And from this we get the indication that the line has been Orifice.

Q-5 - Orifice Tab Q is installed?

Answer- Reason for setting up Orifice Table

We get the Indication of Orifice tab in 1 - line.

2 - There is a marking of the Diameter above it.

3 - His material is also written in Orifice.

4 - The tag number of Orifice is mentioned above.

5 - There is also a marking of the inlet of Orifice.

Q-6 - How is H.P (inlet) side detected in Orifice?

Answer - The orifice has a marking of the H.P (inlet) side. Wherever we come to know the inlet side.

Q-7- How to calibrate -D.P transmitter?

Answer- Transmitter calibration steps are below

1 - First of all we will adjust the zero of the transmitter.

2 - Static pressure test - In which the transmitter is given the same pressure from both sides. After giving presser, we should get zero on DP.

3 - Will do vacuum test - Uniform vacuum is given from both sides. At that time also DP should get zero.

4 - Pressure is adjusted by giving pressure on high side.

5 - Zero can adjust again if needed.

Q-8 - The flow in the transmitter is not high, how will they check?

Answer-

1 - We will flush the transmitter. In this, HP will flush the LP Impulse line.

2 - Zero will adjust by opening the equalization valve.

3 - Will check line jam on LP side. And clean it.

4 - Will check leakage in it.

5 - Calibration will do.

Q-11 - Describe the type of pressure? Types of Pressure?

Answer - There are three main types of pressure

1 - Atmospheric Pressure

2 - gauge pressure

3 - Absolute Pressure

Q-12 - What is absolute pressure?

Answer - The current pressure in any system is called absolute pressure. It can also be understood from the formula below.

Absolute Pressure = Gauge Pressure + Atmospheric Pressure

Q-13 - What is atmospheric pressure?

Answer - The pressure exerted by the pressure of atmosphere is called atmospheric pressure. At high altitudes, the air pressure is low, hence the atmospheric pressure is also low. Usually it is 1KG / CM2.

Q-14 - What is gauge pressure?

Answer- Whatever pressure we see above the atomospheric pressure is called a gauge pressure. Atmospheric pressure is normally 1KG / CM2.

Q15 - What is vacuum pressure?

Answer- Even where there is less pressure than atomospheric pressure, it will be called vacuum pressure.

Q-16 - Which measuring  instrument is used to measure pressure.

Answer- The instrument given below is used to do pressure majors.

1 - Diaphragm

2 - Burden Tube

3 - Bello

4 - capsule

5 - Pressure Spring

Q-17 - Pressure gauge works on which principle?

Answer- Pressure gauge works on the principle of "hook lo". Measuring the stress on elastic is called hook of low.

Q-18 - Describe the parts of the pressure gauge. Parts of pg

Answer-

1 - C 'Type Burden Tube

2 - Sector Gear

3 - Connecting Link

4 - Pinion Gear

5 - Pointer

6 - Hair Spring

7 – Dial

Q-19 - Describe the different method of measuring temperature?

Answer - There are two main methods of measuring temperature.

1 - Mechanical method

2 - Electrical method

Methods of measuring temperature in mechanical method

1 - Temperature can be measured by placing mercury in a glass thermometer.

2 - Bimetallic thermometer can measure temperature.

3 - Pressure Spring Thermometer

Methods of temperature measurement by electrical method

1 - Can check temperature with thermocouple.

2 - RTD - Resistance can measure temperature with temperature detector.

Q-20 - What is the meaning of PT-100 and PT-1000?

Answer -PT-100 means PT means platinum, and 100 means 100 ohm per 00 C temperature. Likewise, PT means 1000 in platinum, and 1000 means 1000 ohm per 00 C temperature.

Q-21 - Why is thermowell applied?

Answer - There are many such applications in the factory, where we cannot bring direct temperature sensor into contact. Thermovale is used to measure the temperature of such place. In addition, there is no chemical effect on the sensor, so no thermosevel is also preferred. Applying a thermowell can protect the sensor from physical damage during operation.

Q-22 - Which materials are used for thermowell?

Answer- The main four materials are used for thermowells.

1 - Alloy Steel

2 - Stainless Steel

3 - Inconel

4 - Monel

Q-23 - Who is used to major low temperature?

Answer- RTD (resistance temperature detector) is used to measure low temperature.

Q-24 - What does skin temperature thermocouple mean?

Answer - Touch with direct material. It does not use any type of thermowell, hence it is called skin thermocouple. It is used to measure the temperature of heater, furnace and fuel gas.

Q-25 - What is the difference between thermocouple and twin wire RTD?
Answer-

1 - In wire RTD the color of the wire is red and white. Whereas the wire of a thermocouple is the basis of its type.

The 2-thermocouple has a plus and minus signal. There is no such signal in RTD.

3-The thermocouple increases the temperature as the temperature increases. The temperature in RTD increases as the resistance increases. On the basis of the vault and resistance, we can also detect RTD and thermocouple.

Q-26 - What are the active and passive components in instrumentation?

Answer- The instrument which needs an ode of spring for operation. It is called Active Component.

For example - devices like transmitter, control valve, PID controller and indicator are called active components.

The device, which does not require any hymn outside, is called a passive component.

For example - devices like RTD (resistance temperature detector), pressure gauge, temperature gauge, thermocouple do not need any external hymn.

Q-27 - Which type of pneumatic control valve is?

Answer - The types of pneumatic control valves are given below.

1 - globe valve

2 - Butter Fly Valve

3 - Ball valve (A) On off valve (B) Continue open valve

4 - Air to open valve

5-year then close valve

Q-28 - How is the signal of temperature from field to PLC, DCS and controller?

Answer–

The signal of the temperature matches both the RTD and the thermocouple. It is transferred in two ways.

1 - Direct - In this the wire of RTD and thermocouple is directly connected to PLC, DCS and controller.

2 - Using the temperature transmitter - The temperature transmitter first converts the signal from the RTD and thermocouple to 4 to 20 MA. This signal is sent to the PLC, DCS and controller.

Instrumentation Interview Questions and Answers

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Instrumentation Interview Questions and Answers