Instrument Engineer
100+ Instrument Engineer Interview Questions and Answers
Q51. Why we use MOV.
MOV (Metal Oxide Varistor) is used as a voltage protection device in electrical circuits.
MOV is used to protect sensitive electronic devices from voltage surges or transients.
It acts as a voltage-dependent resistor, limiting the voltage across the circuit.
MOV absorbs excess voltage and diverts it away from the protected equipment.
It has a high resistance at normal operating voltage and low resistance during voltage spikes.
MOV is commonly used in power supplies, surge protecto...read more
Q52. What is roll of Three element system at boiler?
Three element system at boiler is used to control the water level, steam flow, and feed water flow to maintain optimal boiler operation.
Three element system monitors water level, steam flow, and feed water flow in a boiler.
It helps in maintaining the water level within safe limits to prevent damage to the boiler.
The system adjusts the feed water flow based on the steam flow to maintain a constant water level.
It ensures efficient and safe operation of the boiler by controlling...read more
Q53. What are the type of calibration before you done ?
There are different types of calibration that can be done depending on the instrument being used.
Zero calibration
Span calibration
Linearity calibration
Sensitivity calibration
Temperature calibration
Humidity calibration
Pressure calibration
Q54. Difference between Ac Drive and DC Drive
AC drives use alternating current to control the speed of an electric motor, while DC drives use direct current for the same purpose.
AC drives are more commonly used due to their ability to provide variable speed control and energy efficiency.
DC drives are simpler in design and are often used in applications where precise speed control is required, such as in cranes or elevators.
AC drives are typically more cost-effective and easier to maintain compared to DC drives.
Examples ...read more
Q55. How can you identify the cable in cable drum
Cables in a cable drum can be identified by checking the cable tags, color coding, cable length, and cable type.
Check the cable tags for identification information
Look for color coding on the cables
Measure the cable length to match with specifications
Identify the cable type based on markings or specifications
Q56. What's the inputs and outputs
Inputs and outputs refer to the signals or data that are received and transmitted by a system or device.
Inputs are the signals or data that are received by a system or device, which are then processed or used to produce an output.
Outputs are the signals or data that are transmitted by a system or device, which are the result of processing the inputs.
Examples of inputs and outputs include sensors and actuators in a control system, audio and video signals in a multimedia system...read more
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Q57. What is the control valve and their part names.
Control valves are devices used to regulate the flow of fluids in a system by varying the size of the flow passage.
Control valves have various parts including valve body, actuator, positioner, and valve trim.
Valve body is the main part of the control valve that houses the internal components.
Actuator is responsible for moving the valve plug to control the flow.
Positioner ensures the valve plug is in the correct position based on the control signal.
Valve trim consists of the p...read more
Q58. Difference between Star/Delta starter for motor?
Star/Delta starter is used to reduce the starting current of a motor.
Star connection provides high starting torque but high starting current
Delta connection provides low starting torque but low starting current
Star/Delta starter uses both connections to reduce starting current and provide sufficient starting torque
Used for large motors to prevent damage to motor and electrical system
Instrument Engineer Jobs
Q59. What is the flame scanner working principle?
Flame scanner detects the presence or absence of flame in a combustion chamber.
Uses ultraviolet or infrared radiation to detect flame
Sends signal to control system to adjust fuel and air flow
Helps prevent explosions and improve efficiency
Commonly used in boilers, furnaces, and gas turbines
Q60. What is instrumentation
Instrumentation is the science and art of measurement and control of process variables within a production or manufacturing area.
Instrumentation involves the use of sensors, transmitters, controllers, and final control elements to monitor and control processes.
Examples of instrumentation include pressure gauges, temperature sensors, flow meters, and control valves.
Instrumentation plays a crucial role in ensuring the efficiency, safety, and quality of industrial processes.
Q61. What is Lead Resistance
Lead resistance is the resistance encountered in the electrical leads connecting a sensor or instrument to a measuring device.
Lead resistance can affect the accuracy of measurements by introducing additional resistance in the circuit.
It is important to account for lead resistance when designing and calibrating instrumentation systems.
Lead resistance can be minimized by using high-quality, low-resistance leads.
Examples of instruments where lead resistance is a concern include ...read more
Q62. Types of steam turbines and working
Steam turbines are used to generate electricity by converting thermal energy into mechanical energy.
There are two main types of steam turbines: impulse turbines and reaction turbines.
Impulse turbines use high-pressure steam to rotate a set of blades, while reaction turbines use both high-pressure and low-pressure steam to rotate a set of blades.
Steam turbines are commonly used in power plants to generate electricity.
The largest steam turbine in the world is located in South K...read more
Q63. What is plc and dcs
PLC stands for Programmable Logic Controller and DCS stands for Distributed Control System.
PLC is a digital computer used for automation of electromechanical processes.
DCS is a control system used to control complex processes in industries.
PLC is used in discrete manufacturing industries while DCS is used in continuous process industries.
PLC is programmed using ladder logic while DCS is programmed using function blocks.
Examples of PLC include Siemens S7-1200 and Allen Bradley...read more
Q64. What can you tell me about level transmitters?
Level transmitters are instruments used to measure the level of a substance in a container or tank.
Level transmitters use various technologies such as ultrasonic, radar, capacitance, and pressure to measure levels.
They provide continuous level measurement and can be used in various industries like oil and gas, chemical, and water treatment.
Level transmitters can be installed externally or directly in the substance being measured.
They transmit the level data to a control syste...read more
Q65. What is RTD FULL FORM and brief description
RTD stands for Resistance Temperature Detector. It is a temperature sensor that operates on the principle that the resistance of a metal increases with temperature.
RTD is commonly used in industrial applications for temperature measurement.
Platinum is a popular material for RTDs due to its high accuracy and stability.
RTDs are known for their high accuracy and repeatability compared to other temperature sensors.
RTDs are commonly used in industries such as oil and gas, chemical...read more
Q66. Can we use 0-10 v in plc?
Yes, 0-10 V can be used in PLC as an analog input or output signal.
PLCs typically have analog input and output modules that can handle 0-10 V signals.
The signal can be used to measure or control variables such as temperature, pressure, or flow.
The resolution and accuracy of the signal depend on the PLC and the analog module used.
Some PLCs may require additional scaling or conversion of the signal to match the desired range or units.
Examples of PLCs that can use 0-10 V signals...read more
Q67. What is your PLC programming language?
I am proficient in ladder logic programming for PLCs.
Proficient in ladder logic programming for PLCs
Experience with other PLC programming languages such as Function Block Diagram (FBD) and Structured Text (ST)
Knowledge of industry standards for PLC programming
Ability to troubleshoot and debug PLC programs
Examples: Allen-Bradley RSLogix, Siemens TIA Portal, Mitsubishi GX Works
Q68. How to so control valve maintenance
Control valve maintenance involves regular inspection, testing, and calibration to ensure optimal performance.
Regularly inspect control valves for leaks, corrosion, or damage
Perform testing to check for proper functioning and response time
Calibrate control valves to ensure accurate control of flow rates
Replace worn out parts or components as needed
Keep detailed records of maintenance activities for future reference
Q69. Various types Communication protocol
Various types of communication protocols include Modbus, Profibus, HART, Foundation Fieldbus, and Ethernet/IP.
Modbus - commonly used in industrial automation
Profibus - used in process automation
HART - for smart field devices
Foundation Fieldbus - for process control
Ethernet/IP - for industrial Ethernet communication
Q70. What is instrumentation skill?
Instrumentation skill refers to the ability to design, install, maintain, and troubleshoot various types of instruments used in industrial processes.
Understanding of different types of instruments such as sensors, transmitters, controllers, and final control elements
Knowledge of calibration procedures and techniques
Ability to read and interpret P&IDs (Piping and Instrumentation Diagrams)
Proficiency in using software tools for data analysis and visualization
Troubleshooting ski...read more
Q71. Describe different types of flow
Different types of flow include laminar, turbulent, transitional, compressible, incompressible, steady, and unsteady.
Laminar flow: smooth and orderly flow with no turbulence
Turbulent flow: chaotic and irregular flow with eddies and swirls
Transitional flow: a mix of laminar and turbulent flow
Compressible flow: flow where the density changes due to pressure changes
Incompressible flow: flow where the density remains constant
Steady flow: flow where the velocity and other properti...read more
Q72. Working principle of mass flow meter
Mass flow meter measures the mass flow rate of a fluid in a pipe or duct.
Works on the principle of Coriolis effect or thermal dispersion
Fluid flows through a vibrating tube or a heated element
Measures the change in frequency or temperature to determine mass flow rate
Used in industries like chemical, food and beverage, and oil and gas
Examples include Coriolis mass flow meter and thermal mass flow meter
Q73. What is hydrolic & pneumatic pressure
Hydraulic pressure is the force exerted by a fluid in a closed system, while pneumatic pressure is the force exerted by a gas in a closed system.
Hydraulic pressure is generated by the movement of a liquid, such as oil, in a confined space.
Pneumatic pressure is created by the compression of a gas, such as air, in a closed system.
Both types of pressure are used in various industrial applications, such as in hydraulic systems for heavy machinery or pneumatic systems for air tool...read more
Q74. Pressure temperature flow level
Pressure, temperature, flow, and level are key parameters in instrumentation engineering.
Pressure is the force exerted by a fluid on its container, measured in units like psi or bar.
Temperature is the degree of hotness or coldness of a substance, measured in units like Celsius or Fahrenheit.
Flow is the rate at which a fluid passes through a system, measured in units like liters per minute.
Level is the height of a substance in a container, measured in units like meters or feet...read more
Q75. mentioned Standard maintenance procedure for instruments
Standard maintenance procedures for instruments involve regular inspections, calibrations, and repairs to ensure optimal performance.
Regularly inspect instruments for any signs of wear or damage
Calibrate instruments according to manufacturer's guidelines
Perform routine maintenance tasks such as cleaning and lubricating
Keep detailed records of maintenance activities for each instrument
Train staff on proper instrument maintenance procedures
Schedule preventive maintenance to avo...read more
Q76. Difference between interacting and non interacting system
Interacting systems have feedback loops and can influence each other's behavior, while non-interacting systems operate independently.
Interacting systems have mutual dependencies and can affect each other's inputs, outputs, or behavior.
Non-interacting systems operate independently and do not have any influence on each other.
Interacting systems often involve feedback loops where the output of one system affects the input of another.
Non-interacting systems can be considered as s...read more
Q77. Please explain the VFD and its block digram
VFD stands for Variable Frequency Drive, used to control the speed of an AC motor by varying the frequency and voltage supplied to the motor.
VFD consists of three main components: rectifier, DC bus, and inverter.
Rectifier converts AC power to DC power.
DC bus stores the converted DC power.
Inverter converts DC power back to AC power with variable frequency and voltage.
VFD allows for precise control of motor speed, reducing energy consumption and wear on the motor.
Example: VFDs ...read more
Q78. What is Automation
Automation is the use of technology to control and monitor processes, reducing human intervention.
Automation involves the use of control systems to operate equipment and machinery.
It aims to increase efficiency, productivity, and safety by minimizing human error.
Examples include automated manufacturing processes, smart home systems, and self-driving cars.
Q79. Instruments which power AI voltage
Instruments that power AI voltage include sensors, transducers, and signal conditioners.
Sensors convert physical parameters into electrical signals.
Transducers convert one form of energy into another.
Signal conditioners amplify, filter, and convert signals for processing.
Examples include thermocouples, pressure sensors, and strain gauges.
Q80. Tell the plc used in your plant
The PLC used in our plant is Siemens S7-1200.
Siemens S7-1200 is a popular choice for industrial automation due to its reliability and flexibility
It offers a wide range of communication options and programming capabilities
The PLC is used for controlling various processes and equipment in the plant
Q81. Allow you to select the topic you are good at
I am good at process control systems
Experienced in designing and implementing control systems for industrial processes
Skilled in programming PLCs and SCADA systems
Knowledgeable in instrumentation devices such as sensors, transmitters, and control valves
Q82. Each And Every Process Variable Measurement
Process variable measurements are essential for monitoring and controlling industrial processes.
Process variables include temperature, pressure, flow rate, level, pH, conductivity, etc.
Measurements are typically done using sensors and transmitters.
Accurate measurements are crucial for ensuring process efficiency and safety.
Examples of instrumentation used for measurement include thermocouples, pressure transducers, flow meters, level sensors, etc.
Q83. How to prepare Transmitter Datasheet?
To prepare a Transmitter Datasheet, include key specifications like range, accuracy, output signal, process connection, etc.
Include key specifications such as range, accuracy, output signal, process connection, etc.
Provide details on power supply requirements and environmental conditions.
Specify any special features or certifications required for the application.
Include information on calibration procedures and maintenance requirements.
Ensure all necessary dimensions and moun...read more
Q84. What is Control valve function?
Control valve function is to regulate the flow of fluid in a process system by varying the size of the flow passage.
Regulates flow of fluid by adjusting flow passage size
Controls pressure, temperature, level, or flow rate in a process system
Can be operated manually or automatically
Examples: globe valve, butterfly valve, ball valve
Q85. Process variable and control system?
Process variable is the measured parameter in a system, while control system is the mechanism used to regulate the process variable.
Process variable is the input to the control system
Control system uses feedback to adjust the process variable
Examples of process variables include temperature, pressure, flow rate
Examples of control systems include PID controllers, PLCs, DCSs
Q86. Network topology types
Network topology types refer to the layout of a computer network and how different devices are connected.
Common types include star, bus, ring, mesh, and hybrid topologies
Star topology has a central hub with all devices connected to it
Bus topology uses a single cable to connect all devices in a linear fashion
Ring topology connects devices in a circular manner
Mesh topology has each device connected to every other device
Hybrid topology is a combination of two or more different t...read more
Q87. Field instruments with their working principles
Field instruments are devices used to measure and control process variables in industrial settings.
Working principles include pressure, temperature, level, flow, and analytical measurements
Examples include pressure transmitters, thermocouples, level switches, flow meters, and gas chromatographs
Instruments can be analog or digital, and may use various communication protocols such as HART or Modbus
Q88. Draw a hook drawings for DP level transmitters
A hook drawing for DP level transmitters is a diagram that illustrates the installation and connection of the transmitter in a process system.
The hook drawing typically includes details such as the location of the transmitter, the process connections, and the electrical connections.
It may also include information about the type of transmitter, the range, and any additional accessories or components.
The hook drawing helps ensure proper installation and connection of the DP lev...read more
Q89. Tell about turbine protection system.
Turbine protection system is a safety system that protects the turbine from damage during abnormal conditions.
It monitors various parameters like temperature, pressure, vibration, and speed.
It triggers alarms and trips the turbine if any parameter exceeds the safe limit.
It also includes emergency shutdown systems to prevent catastrophic failures.
Examples of protection systems include overspeed protection, low oil pressure protection, and high exhaust temperature protection.
Q90. Plc HMI of working condition instrument
PLC HMI is a crucial component in ensuring the proper functioning of instruments in industrial settings.
PLC HMI (Programmable Logic Controller Human Machine Interface) allows operators to monitor and control the instrument's working conditions.
It provides real-time data, alarms, and notifications to ensure smooth operation.
Examples of working condition instruments include temperature sensors, pressure gauges, flow meters, etc.
Q91. input for Control valve sizing
Control valve sizing requires accurate input data to ensure proper valve selection and performance.
Process fluid properties such as density, viscosity, and pressure drop
Flow rate and flow characteristics
Piping and valve specifications
Control system requirements
Environmental factors such as temperature and altitude
Consideration of safety and reliability
Examples of input data include P&ID diagrams, process data sheets, and equipment specifications
Q92. Different flow characteristics of pump
Different flow characteristics of pump include centrifugal, positive displacement, axial, and mixed flow.
Centrifugal pumps are commonly used for low viscosity fluids and high flow rates.
Positive displacement pumps are suitable for high viscosity fluids and low flow rates.
Axial flow pumps are used for high flow rates and low head applications.
Mixed flow pumps combine features of both centrifugal and axial flow pumps.
Q93. What is a Control valve CV
A control valve CV is a device used to control the flow of fluid in a system by varying the size of the flow passage.
Control valves are commonly used in industries such as oil and gas, chemical, and power plants.
They can be operated manually or automatically using an actuator.
Control valves can regulate variables such as flow rate, pressure, temperature, and level in a process system.
Examples of control valve manufacturers include Fisher, Emerson, and Valtek.
Q94. Types of Control valves, Types of transmiteers etc
Control valves include globe, butterfly, ball, and plug valves. Transmitters include pressure, temperature, level, and flow transmitters.
Types of control valves: globe, butterfly, ball, plug
Types of transmitters: pressure, temperature, level, flow
Examples: Globe valve, Pressure transmitter
Q95. What are Spi modules
SPI modules are communication interfaces used to transfer data between microcontrollers and peripheral devices.
SPI stands for Serial Peripheral Interface
It is a synchronous communication protocol
SPI modules have a master-slave architecture
Data is transferred in full duplex mode
Commonly used in microcontroller-based systems for communication with sensors, displays, and memory devices
Q96. CV calculation of control Valve?
CV calculation of control valve involves determining the valve's flow coefficient.
CV is calculated using the formula: CV = Q / (SG * sqrt(dP))
Q is the flow rate, SG is the specific gravity of the fluid, and dP is the pressure drop across the valve.
CV is used to select the appropriate valve size for a given application.
Factors such as valve type, trim size, and pressure drop affect the CV value.
CV calculation is important for ensuring proper control of fluid flow in industrial...read more
Q97. Explain 3 element drum level control.
Three element drum level control is a method of controlling the water level in a steam drum using three inputs.
The three inputs are steam flow, feedwater flow, and drum level.
The steam flow and feedwater flow are used to calculate the rate of change of drum level.
The drum level is then adjusted based on the calculated rate of change.
This method provides better control than single or two element control.
It can prevent boiler damage due to low water levels or carryover of water...read more
Q98. Explain three element method of boiler?
The three element method of boiler is a control strategy that uses three variables to maintain water level and steam flow.
The three variables are steam flow, water flow, and drum level.
The steam flow and water flow are measured by flow meters.
The drum level is measured by a level transmitter.
The controller compares the steam flow and water flow to maintain a balance.
If the drum level drops, the controller increases the water flow to maintain the level.
If the steam flow increa...read more
Q99. Types of Boiler and working
Boilers are vessels that heat water or other fluids to generate steam or hot water for various applications.
Fire-tube boilers: hot gases from combustion pass through tubes submerged in water
Water-tube boilers: water flows through tubes and hot gases from combustion surround them
Electric boilers: use electricity to generate heat and produce steam or hot water
Condensing boilers: extract additional heat from the exhaust gases to increase efficiency
Q100. DP TYPE LT working and configuration
DP type LT stands for Differential Pressure type Level Transmitter used for measuring level in tanks or vessels.
DP type LT measures level by detecting the pressure difference between two points in a vessel.
It consists of two pressure sensors connected to the top and bottom of the tank.
The configuration involves setting the zero and span points to calibrate the transmitter.
Commonly used in industries like oil & gas, chemical, and water treatment.
Example: Rosemount 3051S DP Lev...read more
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