LME21.550C2 Siemens Burner Control

Overview

The Siemens LME21.550C2 is a high-performance, microcomputer-based burner control designed for the startup and supervision of 1- or 2-stage gas or gas/oil burners. Engineered for intermittent operation, this control unit is suitable for burners of small to medium capacity, with or without a fan. It provides critical safety functions through advanced digital signal handling and is often utilized by original equipment manufacturers (OEMs) for integration into diverse combustion systems. The LME21.550C2 is identical in housing dimensions to the legacy LGB and LMG series, making it a reliable modern replacement.

Features

• Microcomputer-controlled sequence ensures high accuracy and repeatable performance
• Undervoltage detection for enhanced system safety during power fluctuations
• Air pressure supervision with a functional check of the air pressure switch during startup and operation
• Multicolor LED indication provides clear fault status and operational messages for simplified troubleshooting
• Electrical remote reset facility allows for convenient system management
• Limitation of the number of repetitions to prevent unsafe restart attempts
• Controlled intermittent operation triggers a safety shutdown after a maximum of 24 hours of continuous operation

Specifications

• Model: LME21.550C2
• Supply Voltage: AC 230 V (50/60 Hz)
• Burner Stages: 2-stage control
• Prepurge Time (t1): 50 seconds
• Safety Time (TSA): 5 seconds
• Preignition Time: 4 seconds
• Flame Supervision: Ionization probe or QRA flame detector (with AGQ3 ancillary unit)
• Power Consumption: Approximately 12 VA
• Protection Rating: IP40 (when integrated with appropriate base)
• Weight: 0.118 kg (0.26 lb)

Applications

• Supervision of 1- or 2-stage gas or gas/oil burners in commercial and industrial HVAC systems
• Ideal for use in automatic forced draft burners for gaseous fuels in accordance with EN 676
• Suitable for systems requiring intermittent operation (at least one controlled shutdown every 24 hours)
• Compatible with various flame sensors, including ionization probes and UV detectors for blue-burning or forced-draft flames
• Integration into gas trains and burner management systems for boilers and thermal process plants