Siemens 7ML5431-0AA00-1AA1 SITRANS LR250 Radar Level Transmitter Unit

Module Feature

7ML5431-0AA00-1AA1 is the order code of Siemens SITRANS LR250 FMCW radar level transmitter.

It adopts 25GHz frequency modulated continuous wave radar technology for non-contact liquid level detection. Equipped with horn antenna, good suppression for steam, foam and light turbulence surface. Supports two-wire 4-20mA output and HART digital communication, local LCD display for on-site parameter checking. Compact integrated design, corrosion resistant antenna material, explosion-proof certification optional. Widely stocked as maintenance spare for buffer tank, raw water tank, solvent tank and process vessel level monitoring skid.

Working principle

The transmitter emits frequency-modulated microwave signal towards the liquid surface.

The wave reflected back from medium surface is received by antenna. The internal electronics calculate time difference between transmitted and reflected signal to convert into level height value. The measured level value is converted to 4-20mA analog signal and HART digital data, uploaded to DCS or PLC system. Built-in echo processing algorithm filters false echoes from tank wall, baffles and obstacles.

Onboard components

Radar RF transceiver board, signal processing CPU, HART communication chip, LCD local display, horn antenna assembly, sealing gland, wiring terminal block and aluminum alloy housing.

LED indicators

Local LCD screen displays level value, echo curve and fault codes. Status LED on display module for power and alarm indication.

Hardware self‑diagnosis

Built-in supervision detects antenna contamination, echo loss, loop fault and internal electronic failure. Configuration and echo curve analysis are completed by Siemens SIMATIC PDM software.

Programming softwareSIMATIC PDM, used for tank shape setup, false echo mapping, 4-20mA range configuration and diagnostic data reading.

Electrical & Process Parameters

Model:7ML5431-0AA00-1AA1 Brand:Siemens Device type:SITRANS LR250 radar level transmitter Function:Continuous non-contact level measurement for liquid storage and process vessels

Mechanical & Structure

Mounting:Thread or flange mounting on tank top Protection class:IP67 Housing:Die-cast aluminum sealed enclosure

Environmental

Operating temperature:-40℃ ~ +80℃ Storage temperature:-40℃ ~ +85℃ Ambient humidity:5~95% non‑condensing

Certification:CE, ATEX/IECEx optional Status:Original Siemens level instrument spare

Installation

Disconnect loop power before replacement.

Install transmitter away from tank inlet and internal baffles, complete two-wire 4-20mA HART wiring, set tank height and empty/full calibration, test level reading and false echo suppression function after commissioning.

Interface

Two-wire 4-20mA / HART loop terminals, horn antenna process interface.

Diagnostic

No valid echo: Antenna covered by condensate, foam too thick, mounting position blocked. Signal jumping: Turbulent liquid surface, false echo not mapped. HART offline: Loop resistance mismatch, wiring polarity reversed.

Product Brief7ML5431-0AA00-1AA1 transmitter, Siemens SITRANS LR250 25GHz radar level meter spare for process tank level monitoring replacement.