How many types of transmitter

With this signal, a transmitter sends a small current, proportional to the physical measurement, through a set of wires. As shown below, the transmitter produces an output signal of 4 — 20mA when the process variable is applied to the transmitter:. Digital transmitters produce digital signals that are combined in a variety of ways to enhance communication with the devices; enhances diagnostic capabilities of the device and makes control of the devices and processes relatively easy and smooth.

Digital signals are discrete levels or values that are combined in specific ways to represent process variables and also carry other important information, such as diagnostic information. Digital transmitters combine the digital signals in a variety of ways leading to various communication protocols such as Fieldbus, HART etc. Most digital transmitters may be referred to as smart instruments.

They have inbuilt microprocessors that helps in signal conditioning and processing and gives the devices some diagnostic capability. Electronic transmitters can be grouped according to the number of wires necessary to provide transmitter power. Accordingly, there are 2-wire, 3-wire and 4-wire transmitters. Please see Pressure Transmitters Wire Configuration for more details on transmitter wire configuration. In the process industries, there four common process variables of interest:.

In addition to these variables, there is also the need to analyse various chemical compositions and components. Hence accordingly, the following transmitters are commonly used in the process industries:. Pressure transmitters are essentially used in measuring various types of process pressures. We have:. When the pressure gauge reads 0 PSI, it is means pressure is atmospheric.

There are seven types of level transmitters, which include: Point Level : These are designed to provide an output signal when a particular measurement level has been reached. The output signal can be an electrical signal to turn on a switch, or an audible alarm. Continuous Level : This transmitter measures level within a particular range. It is also designed to provide updated measurements as the level changes. Ultrasonic Level Transmitter : Ultrasonic level transmitters allow for non-contact level measurements of bulk solids, or viscous liquids.

Conductive Level : This type is used to measure different types of liquids at point level. Liquids can include water, caustic soda, and hydrochloric acids, and other corrosive fluids. Pneumatic Level : These transmitters are ideal for applications that comprise slurry or sludge. They can be used in applications that does not have electricity. Capacitance Level : This transmitter type is used to provide continuous measurement of non-conductive liquids that have a high dielectric constant.

Some types of transmitters are named after the mounting method, meaning there is some overlap between the type and mounting method. In applications where a transmitter must withstand the wear and tear associated with continuous exposure to the elements, a weather- and explosion-proof transmitter is appropriate. This particular type of transmitter has an external enclosure, usually made of stainless steel or a designated explosion-proof material, which is sealed tightly to protect the sensitive internal components.

Inside, the transmitter is divided into two small chambers: one contains the sensor and the other contains the electronics associated with calculating temperature and transmitting a new signal. Weather-proof and explosion-proof transmitters tend to have a high level of accuracy, and can usually be adjusted and monitored locally, if needed. A DIN rail is used to mount switches, relays, and transmitters.

The rail itself is a piece of metal that is shaped to enable a device such as a transmitter to be attached using a spring clip, which slides into a bend in the metal rail and secures itself. Search for:. By Ted Mortenson. Automation Engineer. Posted on Aug 3, Checkout your email. Have questions? Sign in. Contact Us. All rights reserved. Created with coffee and tea in Rotterdam.