An overview of the Madshen maid power transmitter
One: brief introduction
Madshen Mai De Sheng Electric transmitter transmitter is a device that converts the measured electric parameters (such as current, voltage, power, frequency, power factor and other signals) to DC current and DC voltage, and to isolate analog or digital signals.
Two: Specification
Transmitter is a parameter to be measured (current, voltage, active power, reactive power, active power, reactive power, frequency, phase, power factor, DC voltage, DC current) conversion according to the linear proportional DC current or voltage (pulse output energy) measurement instrument. It is widely used in electrical, petroleum, coal, metallurgy, railway, municipal government and other departments of electrical measurement, automatic control and dispatching system. The analog signal current value of the international standard output of the new transmitter is 4 ~ 20mA, and the two wire loop is widely applied in sending data and controlling some executor that is easy to accept instructions with this standard. It has been the only standard of current telemetry in analog signals. In the current telemetry circuit using two conductors, the transmitter's working power is connected to the reading device, including any other resistors of the sensor's working power and transmission leads, in series.
Three: functional extension
1, programmable display function. According to the magnification and range, the measured data at one side can be displayed, such as primary side current / voltage / power, etc., with adjustable magnification, adjustable range and high accuracy. It can be used directly when the high precision electric side instrument is used.
2, RS485 interface, using MODBUS-RTU protocol, IEE-574 international standard four byte floating point transmission can be connected to PC, and 485 buses can connect 247 electric transmitters at the same time to telemetry, remote control, remote signaling, remote regulation and other &ldquo, four remote &rdquo, function. Through this interface, PLC equipment and all kinds of field bus control devices can be accessed.
Four: working principle
The power transmitter can measure one voltage, current and corresponding power transmitter, or measure the voltage transmitter of single or multichannel voltage, or measure the single or multichannel current transmitter.
Five: advantages
1. It is not susceptible to the influence of the parasitic thermocouple and the resistance pressure drop along the wire and the temperature drift. The transmission line can be used very cheap and finer twisted pair wire.
2, when the output resistance of the current source is large enough, the voltage induced by the magnetic field coupling to the conductor loop will not produce significant effect, because the current caused by the interference source is very small, and the twisted pair can generally be used to resist the interference.
3, capacitance interference will lead to receiver resistance error for 4 ~ 20mA two wire loop receiver resistance is usually 250&Omega (Uout=1 ~ 5V; sampling) the resistance is too small to have a significant error, therefore, allows the wire length longer than the voltage of the telemetry system;
4, each single reading device or recording device can be exchanged between different channels with different lengths. The accuracy difference is not caused by the unequal length of the wires. 5, 4mA is applied to zero level, which makes it convenient to judge open circuit or sensor damage (0mA state).
6, it is easy to add anti surge and lightning protection devices in the two line output port, which is beneficial to safety and lightning protection.
6, the basic classifications and editors of electric quantity transmitters can be divided into current transmitters, voltage transmitters, power factor transmitters, active power transmitters, reactive power transmitters and so on. It can be divided into analog output power transmitter and digital output power transmitter. The output of the transmitter often contains more information.
Relative to analog quantity, digital quantity has strong anti-interference ability, especially using digital signal transmitted by optical fiber, which can avoid loss and interference of transmission link completely, and is suitable for high-precision measurement under complex electromagnetic environment.
