Siemens Burner Controllers LFS Series
Siemens Burner Controllers LFS Series (LFS1 Flame Safeguard) is a flame supervision device designed for industrial oil and gas burners. Depending on the model, it supports RAR9 photocell detectors, QRA ultraviolet flame detectors, and ionization probes. Compatible with Siemens LEC1, LME39.xxxRP, and PLC-based burner control systems, the LFS1 supports continuous or intermittent flame supervision depending on the detector type. Features include multicolor LED diagnostics, a DC 0–10 V flame signal output, BC interface communication, and safety-related applications up to SIL3 under specified conditions.
Product Details
Siemens Burner Controllers LFS Series
Siemens Burner Controllers LFS Series (LFS1 Flame Safeguard)
Siemens LFS Series is a microprocessor-based flame safeguard designed for flame supervision in industrial oil and gas burner applications. It monitors flame detection signals and provides flame status information to burner control systems, supporting safe combustion system operation.
The LFS1 can operate in conjunction with Siemens LEC1 control units, LME39.xxxRP burner controls, and programmable logic controllers (PLCs). Typical applications include industrial burners, boiler systems, industrial heating equipment, and combustion plants requiring reliable flame monitoring.
Key Features
- Flame Supervision: Monitors oil and gas burner flames using compatible flame detectors.
- Continuous Operation: Supports continuous flame supervision with RAR9 photocell detectors or ionization probes, depending on the model.
- Intermittent Operation: Supports QRA ultraviolet flame detectors in intermittent burner applications.
- Multicolor LED Indication: Displays operating conditions and diagnostic information.
- Flame Signal Output: Provides a DC 0–10 V output for flame signal indication.
- BC Interface: Enables parameter configuration and system diagnostics using compatible accessories.
- Safety Functions: Features undervoltage detection and potential-free signal contacts.
Available Siemens LFS1 Models
- LFS1.11A1 / LFS1.11A2: Designed for oil flame supervision using the RAR9 photocell detector in continuous operation.
- LFS1.21A1 / LFS1.21A2: Designed for flame supervision using ionization probes or compatible QRA ultraviolet flame detectors. Operating modes depend on the selected detector.
Industrial Applications
Siemens LFS1 flame safeguards are suitable for industrial combustion systems, boiler burners, industrial heating equipment, and PLC-based burner control applications.
The devices can also be used in dual-flame and multiflame supervision systems, where individual burner flames must be monitored separately.
Selected LFS1 configurations support safety-related industrial applications up to Safety Integrity Level SIL3, subject to the manufacturer's specified operating conditions.
Technical Specifications
Siemens LFS Series Technical Specifications
| Brand | Siemens |
|---|---|
| Series | LFS1 Series |
| Product Type | Flame Safeguard / Flame Supervision Unit |
| Available Models | LFS1.11A1, LFS1.11A2, LFS1.21A1, LFS1.21A2 |
| Fuel Applications | Oil and gas, depending on model and detector |
| Rated Supply Voltage |
AC 120 V (A1 models) AC 230 V (A2 models) |
| Mains Frequency | 50–60 Hz |
| Internal Power Consumption | 5 VA |
| Compatible Flame Detectors |
RAR9 Photocell Detector Ionization Probe QRA2 / QRA2M QRA4 / QRA4M QRA10 / QRA10M |
| Operating Modes |
Continuous Operation:
RAR9 or Ionization Probe Intermittent Operation: QRA UV Flame Detectors |
| Waiting Time (tw) | Maximum 5 seconds |
| Flame-on Response Time (tan) | Minimum 0.3 seconds at factory settings |
| Flame-out Response Time (tab) | Maximum 1 second at factory settings |
| Flame Signal Output | DC 0–10 V (indication only) |
| Communication Interface | BC Interface |
| Output Contacts | Potential-free NO / NC Contacts |
| Degree of Protection | IP40 when correctly mounted |
| Operating Temperature | -20 to +60°C |
| Relative Humidity | Below 95% RH |
| Installation Altitude | Maximum 2,000 m above sea level |
| Applicable Standards |
DIN EN 298 DIN EN 13611 DIN EN 60730-2-5 |
| Safety Integrity Level |
Up to SIL3 with RAR9 or
ionization probes Up to SIL2 with UV detectors, subject to specified conditions |
| Designed Lifecycle |
250,000 burner startup cycles Up to 1,000,000 cycles for industrial applications with switching loads not exceeding 0.1 A |
Reference: Siemens Data Sheet CC1N7782en (29 July 2022). Specifications and operating conditions may vary depending on model, detector configuration, and system settings.
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