What are the differences and connections between transmitters and sensors?

1. What are the differences and connections between transmitters and sensors?

A sensor is a general term for devices or devices that can be measured according to regulations and converted into usable output signals according to certain rules, usually composed of sensitive components and conversion components. When the output of the sensor is a specified standard signal, it is called a transmitter.

Sensor:

The definition of sensors in the national standard GB7665-87 is:; Ldquo; A device or device that can sense a specified measured signal and convert it into a usable signal according to a certain pattern, usually consisting of sensitive components and conversion components; Rdquo;. It is a detection device that can sense the measured information and transform the detected information into electrical signals or other required forms of output according to certain rules, meeting the requirements of information transmission, storage, display, recording and control. It is the primary link to achieve automatic detection and control.
Transmitters:
When a signal converter is integrated with a sensor, it is called a transmitter. According to the definition in the Encyclopedia of China, a transmitter is a sensor that outputs a standard signal.
The definition of a national standard is that a device that outputs a specified standard signal is called a transmitter. The concept of a transmitter is an instrument that converts non-standard electrical signals into standard electrical signals, while a sensor is a device that converts physical signals into electrical signals.

Sensors and transmitters are originally concepts of thermal instruments. Sensors convert non electrical physical quantities such as temperature, pressure, liquid level, material, gas characteristics, etc. into electrical signals or directly send physical quantities such as pressure, liquid level, etc. to transmitters.

The transmitter amplifies the weak electrical signals collected by the sensor for transmission or activation of control components. Or convert the non electrical input from the sensor into electrical signals and amplify them simultaneously for remote measurement and control as a signal source. Analog quantities can also be converted into digital quantities as needed. Sensors and transmitters together form a monitoring signal source for automatic control. Different physical quantities require different sensors and corresponding transmitters. There is another type of transmitter that does not convert physical quantities into electrical signals, such as a boiler water level gauge; Ldquo; Differential pressure transmitter; Rdquo;, He is a remote instrument that sends the water from the lower part of the liquid level sensor and the condensate from the upper part of the steam through the instrument pipe to both sides of the corrugated pipe of the transmitter, and uses the differential pressure on both sides of the corrugated pipe to drive the mechanical amplification device to indicate the water level with a pointer. Of course, there are also transmitters that convert electrical analog quantities into digital quantities. The above is only a conceptual explanation of the difference between sensors and transmitters.

2. Output signals of sensors and transmitters

(1) Current signal: 4-20mA 0-20mA

(2) Voltage signals: 0-5V, 1-5V, etc., and mv signals

(3) Resistance signal

(4) Pulse signal

The above signals can be converted into standard 4-20mA signals through transmission modules or circuit boards. At the same time, the name is no longer a sensor, but a transmitter.
3. What are the two wire and four wire signal transmission methods for transmitters?
In the two-wire transmission method, the power supply, load resistance, and transmitter are connected in series, that is, two wires simultaneously transmit the power supply and output current signal required by the transmitter. Currently, most transmitters are two-wire transmitters; In the four wire system, the power supply and load resistance are respectively connected to the transmitter, that is, the power supply and the output signal of the transmitter are transmitted using two wires. Two wire system refers to the use of only two wires to connect the on-site transmitter with the control room instrument, which are both power and signal wires.

4. Primary and secondary instruments

The professional interpretation of secondary instruments is to accept electrical or pneumatic signals sent by transmitters, converters, sensors (including thermocouples, thermal resistors), etc., and indicate the measured process parameter values of the instrument. Taking physical objects as examples, such as digital display meters, temperature control, etc;
A single meter belongs to signal acquisition and conversion (various transmitter temperature component signal acquisition devices).
The secondary meter is used to display alarm regulation (input from the distributed control system of the panel mounted alarm instrument).

5. The difference between transformer and transformer

The working principle of transformers and transformers is the same, both using the principle of electromagnetic induction. The function of transformers is to transform one level of voltage into another level of voltage with the same frequency. They can only achieve voltage transformation, not power transformation. Transformers are divided into voltage transformers and current transformers. The function of voltage transformers is to supply voltage to measuring instruments, relays, and other devices, To accurately reflect the various operating conditions of the primary electrical system, isolate the secondary electrical systems such as measuring instruments and relays from the primary electrical system to ensure the safety of personnel and secondary equipment, and convert the high voltage of the primary electrical system into the agreed standard low voltage values (100 volts, 100/1.732 volts, 100/3 volts). The function of the power transformer is basically the same as that of the voltage transformer, The difference is that a current transformer converts the large current of the primary electrical system into a standard 5 ampere or 1 ampere supply to the current coil of the measuring instrument The transformer itself has no electricity and can sense energy after being energized by other coils to generate a magnetic field; And transformers are used to change the voltage, for example, a voltage of 100000 volts is transformed into 220 volts through the transformer, which is a tool for changing the voltage and can be reduced or increased!

Mutual inductance transformer is a type of transformer used in practical circuits for direct and impedance conversion, and is often used on input and output interfaces in power and electronic circuits.