Supply units and input isolators

SITRANS I

Transmitter power supply/input isolator 7/5

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Overview

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Application The 7NG4123 transmitter power supply and input isolator is used for the transformation and electrical isolation of standard signals. When it is implemented as a transmitter power supply, it is used for supplying power and transferring signals to two-wire industrial transmitters.

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Design The 7NG4123 transmitter power supply and input isolator is comprised of a compact plastic housing with degree of protec-tion IP 20 and is equipped with push-in screw terminals.•The device is designed for rail mounting (35mm (1.37 inch))•Power is supplied optionally as a flexible low-voltage supply from a wide-input-range power supply unit (95 to 253VAC) or 24VAC/DC (universal current).•On the front are the LEDs for the power supply status indica-tion and the measuring range switch.•Input, output and power supply are electrically isolated. The compact SITRANS I combination power supply for transmitters/ input isolators is used to supply 2-wire transmitters and was designed for the electrical isolation and transformation of standard signals.The required input and output signals are selected with the help of the measuring range switch on the front.

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Function Mode of operation The input signal is applied to the respective input amplifier and converted by a microcontroller in accordance with the transfer function before reaching the output amplifier through an opto-coupler. The signal is amplified and output again as a standard signal (current/voltage).When operating as a transmitter power supply, the connected transmitter is supplied and the transmitter load current is applied to the input amplifier (1). The transfer function can be switched over with the measuring range switch (0/4 to 20 mA, 0/2 to 10 V to 0/4 to 20 mA, 0/2 to 10 V). Calibration is not necessary be- cause all characteristics are stored in the microcontroller.The electrical isolation ensures that the power supply, input cir-cuits and output circuits are completely decoupled for low-cur- rent transfer of the measured values.The measuring range is set with the measuring range switch on the front.

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Benefits •Input signal can be selected (supplying, current or voltage output)•Output signal can be selected (current or voltage output)•Transfer function can be switched over (0/4 to 20mA, 0/2 to10V to 0/4 to 20mA, 0/2 to 10V)•Electrical isolation between input, output and power supply•Power supply status indication through LED on front

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Mode of operation of transmitter power supply and input isolator, SITRANS I Siemens FI 01 · 2008