Transmitters Flashcards
(40 cards)
Which side is your pressure attached to?
High side
Which side is left open to atmosphere?
Low side
How do you connect your electrical leads when calibrating?
Attach positive to test port and negative to the negative port
Where do your leads go inside of a transmitter when calibrating an RTD?
Where you have removed your RTD wires from, 2 separate colours, to imitate the RTD resistance
How does a DP level transmitter measure level?
The different height the liquid is at will give out more or less pressure, full it will have more pressure than 50%.
Where are transducers used on plant and what do they do
They are used as control valve postponers and they convert electrical input to a pressure output
What is the pneumatic air pressure range on a positioned on site
0.2 - 1 bar
Is the actual output from the positioned to the valve actually 0.2 -1 bar?
No there is normally a pressure amplifier that will push up the 0.2 - 1 bar so that it has enough pressure to actually close the valve. Often times the valves may need more to actually push the spring open.
What is the difference between PLC and DCS?
PLC (Programmable Logic Controller) is ideal for discrete control tasks, while DCS (Distributed Control System) is designed for process control tasks. PLCs are used in applications that require robustness, simplicity, and a lower cost. DCSs are preferred for complex control processes where coordination between various processes is necessary.
What is the role of a transducer in instrumentation?
A transducer is a device that converts one form of energy into another. In instrumentation, it’s typically used to convert a physical quantity like pressure or temperature into an electrical signal.
Can you explain what is meant by loop checking in instrumentation?
Loop checking in instrumentation is a process where the performance and connections of control loops are verified. It’s performed to ensure that the control loop is functioning correctly before the process is started.
Explain distributed control system?
A Distributed Control System (DCS) is a control system for a process plant where control elements are distributed throughout the system. This is in contrast to centralized systems that operate from one location.
What is the purpose of an orifice in a pipeline?
An orifice in a pipeline is used to change the fluid flow characteristics, typically to reduce pressure, restrict flow, or measure flow velocity.
What is the difference between intrinsic safety and explosion-proof?
Intrinsic safety refers to equipment and wiring that is inherently safe. In other words, in an explosive atmosphere, it is incapable of causing an explosion. On the other hand, explosion-proof equipment is designed to prevent an internal spark or explosion from causing a much larger blast.
How does a pneumatic control valve work?
pneumatic signal (air pressure). This air pressure is then used to actuate the valve and control the flow of a process fluid
How does a variable frequency drive (VFD) work?
A VFD works by varying the frequency of the electricity supplied to a motor, thereby controlling the speed and torque of the motor. It converts the incoming AC voltage to DC, and then back to a quasi-sinusoidal AC voltage, with the ability to vary the frequency and voltage.
How does a capacitive level sensor work?
A capacitive level sensor works by measuring the change in capacitance caused by the change in the level of a substance. As the level changes, the dielectric constant between the sensor and the substance changes, which in turn changes the capacitance.
What is the purpose of a flame scanner in a boiler?
A flame scanner is used in a boiler to monitor the flame condition, typically using ultraviolet or infrared sensors. It ensures that a flame is present when fuel is being burned and triggers a shutdown if the flame goes out to prevent a dangerous situation.
How does an electro-pneumatic positioner work?
An electro-pneumatic positioner works by receiving an electrical input signal, converting it into a proportional pneumatic output signal, and then using that output to control the position of a control valve or actuator.
What is an I/P converter?
An I/P (Current-to-Pressure) converter is a device that converts a 4-20mA electrical signal into a proportional pneumatic output, typically 3-15 psi or 6- 30 psi. It’s used to interface electrical control devices with pneumatic actuators and valves.
What is the function of a pneumatic system in instrumentation?
A pneumatic system in instrumentation uses compressed air as a medium for transmitting control signals. These systems are often used in industrial control applications due to their reliability, simplicity, and safety.
What is the function of a relay in an electrical circuit?
A relay is an electrically operated switch. It uses a small amount of power to control a larger amount of power by opening or closing contacts in another circuit. When a voltage is applied to the coil, it generates a magnetic field that moves the contacts to turn the relay on or off.
What is the difference between RTD and thermocouple?
Both RTDs (Resistance Temperature Detectors) and thermocouples measure temperature, but they do so in different ways. RTDs work by correlating the resistance of the RTD element with temperature, and they are known for their accuracy. Thermocouples measure temperature based on the Seebeck effect, where a voltage is produced by the temperature difference between two different metals.
How does a differential pressure transmitter work?
A differential pressure transmitter works by sensing the difference in pressure between two points in a system. This is done by having two pressure inlets. The transmitter then outputs a signal proportional to this pressure difference.
