This article describes the difference between a transmitter and a transducer, The transmitter and transducer convert one form of energy into another and output an electrical signal. A transducer converts physical quantity into electrical signal in millivolts(mV) or volts (V), and a transmitter converts mV or volts into milliamps (mA).
A transmitter converts the process measurements into a signal from a sensor and conveys it to a remote indicator or remote display. Whereas, a transducer converts energy from one form to another. Types of energy include mechanical, electrical chemical, electromagnetic, thermal energy, and light.
The difference between the transmitter, and transducer and their characteristics are discussed in this article below.
Transducers convert from one type of physical activity to another including electrical, chemical, motion/pressure, etc. Transducers always contain a sensor as one of their main components.
Examples: Thermometer, accelerometer, proximity sensor, potentiometer, and strain gauge.
A Transmitter- The concept of the transmitter is to convert non-standard electrical signals into the standard electrical signals of the instrument. A type of transmitter may appear to be “like” a transducer, but there is a subtle difference between the two, and perhaps one may be a subset of the other.
Transmitters are current output devices that have two, three, or even four wires. These wires are used to both transmit output current signal and receive power, requiring long cables. The most common electrical standard is a 4-20mA signal. Other types such as 0-20mA and 0-16mA are very rarely used.
Pressure transmitters measure pressure values from a process and amplify them into an equivalent voltage of current. Transmitters are best for sending signals for long distances even over hundreds of meters.
Pressure transmitters are usually connected to pressure transducers. The transmitter is typically calibrated to generate an output current in the range of 4-20 mA or voltage in the range of 1 to 5 V, depending on the type of device.
The difference between Transmitters and Transducers
Transducers and transmitters convert one form of energy into another and an output signal is produced. If the output signal is sent to any device, it can be taken and used to change the pressure in a system.
Transmitters and transducers are almost the same things. Basically, a transmitter and transducer differ in the electrical signal they transmit out. A transmitter produces an electrical signal after conditioning, in mA. Whereas a transducer sends an electrical signal in volts (V) or mV.
Transmitters and transducers are entirely different terms in industrial automation. The two terminologies have slowly combined with the new upcoming technologies that are developing in the field of industrial automation and controls in the area of process measurement.
But with a lot of ongoing research and development activities, manufacturers have started to manufacture miniature transducers with built-in transmitters inside. The size of compact devices is getting smaller and smaller due to the advancement in technology, and improvements in electronics. Some transducers, today have large-scale integrated circuits, leading to the development of small-sized transducer devices.
Transmitters and transducers can be easily differentiated by their working principles as described in this article.
A transmitter will add signal conditioning, obviously allowing it to “transmit” and do the processing. Thus, a transmitter not only converts but also amplifies or filters a signal. Whereas a transducer transforms a physical quantity into another in a “raw” way.
As an example, a PT-100 probe is a transducer. But, if combined with a 4-20mA converter, then it can be called a temperature transmitter.
The transducers are the measuring elements, while the transmitters are the conditioners that permit the raw signal from the transducers to be read, display the measurement, and finally report the final value in the form of analog (4-20mA) or digital.
Common transducer examples include speakers, pressure sensors, and thermometers. But, the best example of the transducer is pressure sensors, torque measurement, and impact sensors.
But, with the development of automation in industries such as power plants, boiler operations, and process instruments are needed to send out the reading over long distances. The output of the transducers is in millivolts (mV), which is necessary for traveling over long distances. The output of the transducer is in millivolts, which is necessary for traveling long distances to control rooms.
Transducers are classified in many ways, here it is presented in the following ways.
- Active and passive Transducers
- Based on construction – Electrical and mechanical Transducers
- Based on output type – Analog and digital transducers
- Classification is also based on transduction phenomena
In terms of efficiency, incandescent lamps are the least efficient. A 100 W lamp in the form of visible light emits a few watts, thereby remaining energy is dissipated as heat and the smallest amount is emitted in the ultra-violet (UV) spectrum.
Transmitter versus Transducer
The difference between the transmitter and transducer can be understood by the following characteristics of the transmitter and transducer.
A transducer detects a physical change and converts it into another form of energy, usually an electrical signal.
A transmitter is usually connected to a transducer, and the device amplifies the output of the transducer to a level that can be transmitted over long distances without distortion.
The transducer sends a signal in the form of milli-volts (mV) or Volts (V). Whereas the transmitter sends signals in standard 4 to 20 mA.
For example, a temperature transducer such as RTD and Thermocouple converts the heat energy into electrical energy. The electrical output signal of the temperature transducer is linear and proportional to the temperature.
The temperature transmitter converts the output of a transducer into a 4-20 mA signal. The current signal is less prone to interference in comparison to a voltage signal.
Transducers are with lower requirements for operating power and power consumption. The power consumption of transmitters is more compared to transducers. This is mainly due to the electronics involved with transmitter design.
Transducers don’t have advanced features. The status of a transducer cannot be checked remotely, it does not possess the smart features of a smart transmitter. Moreover, they are not equipped with display screens to check and note the readings.
In transmitters, the additional electronic circuitry makes the output of a sensor or transducer more linear. Additionally, compensates and eliminates signal noise, and amplifies the lower-level signal to a higher level. Transmitters may comprise local displays and are available in a without-display unit called a blind transmitter. Additionally, the status and diagnostics information of a smart transmitter can be checked with available communicators or remotely using the necessary software.
The transmitters are fitted with simple conditioning units. As a result, the output signal from a transducer is subjected more to electromagnetic interference. On the other hand, transmitter outputs are less susceptible to interference. Transmitter signals can be transmitted over long distances without signal distortion.