Pressure Sensor, Transducer, and Transmitter Explained | Application of Each

Summary

This video explains the distinctions between sensors, transducers, and transmitters in process control. Sensors detect changes in physical variables, while transducers convert these measurements into electrical signals. Not all transducers are sensors, as seen with devices like loudspeakers. A transmitter amplifies and standardizes the signal for further processing by a PLC. The video also contrasts pressure switches and transmitters, highlighting their functional differences. Additionally, RealPars offers a discount on Siemens PLC starter kits for Pro members, including both hardware and software for learning PLC programming. The video provides key insights into these crucial components of industrial automation.

Takeaways

• 😀 A sensor is a device that measures changes in a physical variable and provides an output signal.
• 😀 A transducer converts one form of energy to another and provides an output related to an input variable.
• 😀 All sensors are transducers, but not all transducers are sensors. For example, a loudspeaker is a transducer but not a sensor.
• 😀 A transmitter in process control transmits a standardized electrical signal representing a measured physical variable.
• 😀 Sensors and transducers are used together, with the sensor performing the initial measurement and the transducer converting it into an electrical signal.
• 😀 A pressure transmitter converts a transducer's electrical signal to a standard voltage or current signal (1-5V or 4-20mA).
• 😀 A pressure switch combines a sensing transducer and an electrical switch that opens/closes at a specific pressure.
• 😀 Pressure transmitters and pressure switches are different: transmitters provide continuous analog signals, while switches trigger a simple on/off response at a set pressure.
• 😀 While a pressure transmitter can function as a pressure switch, it is often more complex and expensive than necessary for the task.
• 😀 If you need a simple on/off control based on a specific pressure point, a pressure switch is more practical and cost-effective.
• 😀 RealPars Pro members receive a discount on Siemens PLC starter kits, which include hardware and lifetime access to programming software to enhance learning.

Q & A

What is the main difference between a sensor and a transducer?

A sensor is a device that performs the initial measurement of a physical variable, detecting changes and providing a corresponding output. A transducer, on the other hand, converts one form of energy to another and outputs an electrical or electronic signal.

Can all transducers be considered sensors?

No, not all transducers are sensors. While all sensors are transducers, as they convert physical measurements into electrical signals, not all transducers perform initial measurements. For example, a loudspeaker is a transducer but not a sensor.

What is a transmitter in process control, and how does it work?

In process control, a transmitter is a device that transmits a standard signal (such as 1-5 volts or 4-20 milliamps) to represent a physical variable being measured. This signal is detected by a receiver, such as a PLC or DCS, and is based on the initial measurement provided by a sensor or transducer.

How does a transmitter know what the physical variable is?

The transmitter receives an initial measurement from a sensor or transducer, which detects the physical variable. If necessary, the transducer then converts this measurement into an electrical signal that is further processed and standardized by the transmitter.

What is the role of a pressure switch in a process control system?

A pressure switch consists of a sensing transducer and an electrical switch. It activates or deactivates based on a preset pressure value, typically opening or closing electrical contacts at a specific pressure threshold.

How does a pressure transmitter differ from a pressure switch?

A pressure transmitter converts the output from a sensing transducer into an electrical signal (voltage or current), representing a full range of the physical variable. A pressure switch, however, only opens or closes contacts at a specific pressure setpoint and does not provide a continuous signal.

Can a pressure transmitter function as a pressure switch?

Yes, a pressure transmitter can function as a pressure switch, but it is not practical. A pressure transmitter is typically larger, more expensive, and requires additional configuration, such as scaling and programming in a PLC, compared to the simpler pressure switch.

Why is it easier to use a pressure switch instead of a pressure transmitter for certain applications?

A pressure switch is simpler to install and use, requiring only a digital input on a PLC and straightforward logic. It is ideal for situations where only the detection of a specific pressure threshold is necessary, without needing to know the exact pressure value.

What is the advantage of a RealPars Pro membership?

A RealPars Pro membership provides a discount on Siemens PLC starter kits. It includes lifetime access to the TIA Portal basic software for programming Siemens S7-1200 PLCs, allowing users to learn and practice PLC programming with both hardware and software.

What is included in the Siemens PLC starter kit offered with a RealPars Pro membership?

The Siemens PLC starter kit includes the hardware (Siemens S7-1200 PLC) and lifetime access to the TIA Portal basic software, which is used for PLC programming. This package enables users to learn and practice PLC programming effectively.