Full range of German EPRO transmitters*

GermanyEPRO transmitterFull range*

The transmitter operates based on the principle of negative feedback and is mainly composed of a measuring part, an amplifier, and a feedback part.
The measuring part is used to detect the measured variable x and convert it into an input signal Zi (voltage, current, displacement, force or torque, etc.) that can be accepted by the amplifier. The feedback part converts the output signal y of the transmitter into a feedback signal Zf, and then sends it back to the input end * header * header * header * first input end. The algebra of Zi and the zeroing signal Zo, as well as the feedback signal Zf, need to be compared before entering the amplifier. The difference, ε, needs to be amplified and converted into the standard output signal y.
Transmitters can be divided into two types based on the output signal type: current output type and voltage output type.
(1) The voltage output transmitter has the property of a constant voltage source. The PLC analog signal input first * first * first * first * first * first * first * first enters the module. The impedance of the voltage input first * first * first * first * first * first * first enters the module is very high. If the transmission distance is far, small interference signal currents will generate high interference voltage at the input first * first * first * first * first * first * first enters the impedance of the module. Therefore, the anti-interference ability of remote transmitted analog voltage signals is poor. But it is suitable for sending the same signal to multiple parallel instruments, and the installation is simple. Disassembling and assembling one instrument will not affect the operation of other instruments
(2) The current output type transmitter has the property of a constant current source, which has a high internal resistance. When the PLC analog signal enters the module first, the impedance is low and the interference voltage generated by the interference signal on the module is very low. Therefore, the analog current signal is suitable for remote transmission and can reach hundreds of meters when using shielded cable signal lines.

Full range of German EPRO transmitters*

Current signal transmission and voltage signal transmission each have their own characteristics. Current signals are suitable for long-distance transmission, while voltage signals allow instruments to be connected in parallel. Therefore, in the control table system, the transmission signal entering and leaving the control room adopts current signal, and the connection between various instruments inside the control room adopts voltage signal, that is, the wiring method is current transmission and parallel reception of voltage signal.
The transmitter is divided into two types: two-wire and four wire. The four wire transmitter has two power lines and two signal lines, and there is no strict requirement for the power consumption of the zero point component of the current signal. Two wire transmitters only have two external connections, which are both power and signal lines. The lower limit of the current signal cannot be zero, but two wire transmitters have fewer connections and longer transmission distances, making them suitable for industrial applications.
2. According to the different energy sources used, transmitters are divided into two types: pneumatic transmitters and electric transmitters.
Pneumatic transmitters use dry and clean compressed air as their energy source. They can convert various measured parameters (such as temperature, pressure, flow rate, and liquid level) into pressure signals of 0.02-0.1 IMPa, which can be transmitted to unit combination instruments such as regulation and display for indication, recording, or adjustment. Pneumatic transmitters have a relatively simple structure, reliable operation, strong anti-interference ability against electromagnetic fields, radiation, temperature, humidity and other environmental influences, can prevent fire and explosion, and are relatively cheap in price; The disadvantage is that the response speed is slow, the transmission distance is limited, and it is difficult to connect with a computer.
Electric transmitters use electricity as their energy source, making it convenient for signals to be transmitted over long distances and easy to connect with electronic computers. In recent years, explosion-proof measures have also been implemented for safe use. Its disadvantage is that the investment is generally high and it is greatly affected by temperature, humidity, electromagnetic fields, and radiation interference. Electric transmitters can convert various measured parameters into 0-10mA or 4-20mA (a unified standard signal for DC current) for transmission to other units of the automatic control system.

GermanyEPRO transmitterFull range*

There are many factors that affect the accuracy of transmitters in circuits, mainly including the following.(1) The Influence of Nonlinear Components on Conventional VoltageCurrent transmitters are mostly AC converters (small transformers), and the secondary frequency AC signal is rectified and filteredObtain the final DC signal after stabilizing the voltageDue to the fact that rectifier diodes are nonlinear devices, their voltage and current curves exhibit nonlinear characteristics.(2) The influence of transmitter iron core: In conventional transmitter transformation, iron core material is used as the magnetic medium. On the one hand, due to the nonlinear characteristics exhibited by ferromagnetic materials (the starting and saturation regions of magnetization lines), it is not an ideal linear transmission relationship, which will inevitably affect the accuracy of the transmitter. On the other hand, due to the hysteresis of ferromagnetic materials, the iron core also affects the accuracy of the transmitter. Generally, within the power frequency range, the hysteresis angle of conventional silicon steel sheets varies from 0 ° to 15 °, and the existence of this hysteresis angle is equivalent to increasing the reactive power component. Since conventional power transmitters calculate power by multiplying voltage and current signals, this hysteresis angle will also affect the accuracy of the power transmitter.