In industry, it is necessary to measure various non-electrophysical quantities, such as pressure, liquid level, temperature, differential pressure, temperature and humidity, soil moisture, etc. These physical quantities need to be converted into standard analog electrical signals before they can be transmitted to a control room or display device hundreds of meters away. This device that converts physical quantities into electrical signals is called a transmitter. The most widely used standard analog electrical signal in the industry is to use 4~20mA two-wire DC current to transmit analog current. Transmitter To achieve a two-wire system, the following conditions must be met at the same time: First, v≤emin-imaxrlmax The output voltage v of the transmitter is equal to the specified minimum supply voltage minus the voltage drop of the current across the load resistance and the resistance of the transmission lead. Second, i≤imin The normal operating current of the transmitter i must be less than or equal to the output current of the transmitter. Third, p<imin(emin-iminrlmax) The minimum power consumption p of the transmitter cannot exceed the above formula, which is usually < 90mW. Where: EMIN = minimum supply voltage, EMIN = 24 (1-5%) = 22.8V for most meters, 5% is the allowable negative change of 24V power supply; imax=20ma; imin=4ma; RLMAX = 250Ω + transmission wire resistance. As long as the transmitter is designed to meet the above three conditions, two-wire transmission can be realized. In industrial applications, the measuring point is usually in the field, while the display or control device is usually located in the control room or control cabinet. The distance between the two can be tens to hundreds of meters. According to the distance of 100 meters, the elimination of 2 signal transmission wires means that the cost is reduced by nearly 100 yuan! 4-20mA two-wire signal output is less susceptible to interference, safe and reliable. If you have any questions about product consultation, product customization, agency, technical inquiry, quotation, etc., please contact Xingyi, 400-600-4496!