Burner Controller LGB21.330A27 Plug-in Base 230 V AC

Product Details

The Siemens LGB series consists of compact, electromechanical burner controllers used for the startup and supervision of small to medium-capacity gas or gas/oil burners. While many are being phased out in favor of the electronic LME series, they remain widely used in existing boiler plants and industrial ovens. 1. Popular LGB Models The LGB series is categorized by its timing (pre-purge and safety times) and whether it supports a brushless DC motor or remote reset. Model Application Safety Time (TSA) Pre-purge (t1​) LGB21.330 2-stage gas burner $3$ seconds $30$ seconds LGB21.130 2-stage gas burner $3$ seconds $7$ seconds LGB22.330 2-stage gas/oil $3$ seconds $30$ seconds LGB41.255 Atmospheric gas $5$ seconds $25$ seconds 2. Technical Specifications Mains Voltage: $230\text{V AC}$ ($+10\% / -15\%$) or $100\dots 110\text{V AC}$ variants. Frequency: $50\dots 60\text{ Hz}$. Power Consumption: Approx. $3\text{ VA}$. Flame Monitoring: Ionization probe: Standard for most gas applications. UV Detector: QRA2 / QRA4 / QRA10 (requires an AGQ1 or AGQ2 adapter module for certain LGB models). Protection Class: IP40 (when mounted). Operating Temp: $-20\text{°C}$ to $+60\text{°C}$. Housing: Robust plastic, plug-in design. 3. Key Functional Features Air Pressure Supervision: Monitors the air pressure switch (LDW) during start-up and operation. If the switch fails to close or opens during the cycle, the controller initiates a safety lockout. Intermittent Operation: Designed for systems where the burner shuts down at least once every 24 hours. Compatibility: Uses the standard AGM terminal base, which is physically identical to the newer LME series, making upgrades straightforward. Internal Fuse: Protects the internal contacts against overload. 4. Operational Sequence & Symbols Since the LGB is electromechanical, it uses a sequence switch. During a lockout, the position of the indicator behind the reset button reveals the cause: No Symbol: Failure to start (e.g., no "start" signal or faulty thermostat). $P$: Lockout because the air pressure signal is missing. $\blacktriangle$: Lockout due to a flame signal (extraneous light) being present during the pre-purge phase. $1$: Lockout because no flame was detected at the end of the safety time ($TSA$). 5. Connection Terminals The LGB typically utilizes a 12-terminal or 24-terminal base: Terminal 1: Phase/Live ($L$). Terminal 2: Neutral ($N$). Terminal 3: Fan motor. Terminal 4: Air pressure switch. Terminal 7: Ignition transformer. Terminal 11/12: Fuel valves. Note: When replacing an LGB with a newer LME model, the wiring is usually a 1-to-1 match, but you must ensure the safety time ($TSA$) of the new controller matches the requirements of your specific burner.