Siemens LMO44.255C2 - User Manual

The Siemens LMO14..., LMO24..., and LMO44... series are microcontroller-based oil burner controls designed for the startup, supervision, and control of forced draft oil burners operating in intermittent mode. These controls are suitable for standard versions with an oil throughput up to 30 kg/h, with special versions available for throughputs exceeding 30 kg/h. These devices are primarily intended for use by Original Equipment Manufacturers (OEMs) who integrate burner controls into their products.

Function Description:

The LMO... series controls are engineered to manage the ignition and operation of 1- or 2-stage forced draft oil burners. They supervise yellow-burning flames using photo resistive detectors (QRB...) and blue-burning flames with blue-flame detectors (QRC...). The control sequence is precise and reproducible due to digital signal handling. Key functions include undervoltage detection, electrical remote reset, and a bridging contact for oil preheaters, along with monitoring the preheater's time. The LMO... series ensures controlled intermittent operation after 24 hours of continuous running and limits the number of repetitions to prevent excessive wear. In the event of a fault, the device provides multicolor indication of the fault status and operational messages.

Important Technical Specifications:

Mains Voltage: AC 230 V +10% / -15% or AC 120 V +10% / -15%.
Mains Frequency: 50...60 Hz ±6%.
External Primary Fuse (Si): 6.3 A (slow).
Power Consumption: 12 VA.
Weight: Approximately 200 g (burner control with plug-in base).
Safety Class: I.
Degree of Protection: IP40 (to be ensured through mounting).
Permissible Cable Lengths: Max. 3 m at a line capacitance of 100 pF/m for detector cable laid separately, and 20 m for remote reset laid separately.
Permissible Current at cosφ ≥ 0.6:
- Terminal 1: Max. 5 A (LMO14..., LMO24..., LMO44...).
- Terminals 3 and 8: Max. 3 A (LMO14..., LMO24..., LMO44...).
- Terminals 4 and 5: Max. 1 A (LMO14..., LMO24..., LMO44...).
- Terminal 6: Max. 1 A (LMO14..., LMO24..., LMO44...).
- Terminal 10: Max. 1 A (LMO14..., LMO24..., LMO44...).
Detector Current (QRB.../QRC...):
- Required (with flame): Min. 45 μA.
- Permissible (without flame): Max. 5.5 μA.
- Possible (with flame, typically): 100 μA (QRB...), 70 μA (QRC...).
Environmental Conditions (Storage, Transport, Operation):
- Climatic Conditions: Class 1K3 (Storage), Class 2K2 (Transport), Class 3K3 (Operation).
- Mechanical Conditions: Class 1M2 (Storage), Class 2M2 (Transport), Class 3M3 (Operation).
- Temperature Range: -20...+60 °C (Storage, Transport, LMO44... Operation), -5...+60 °C (LMO14.../LMO24... Operation).
- Humidity: <95% r.h.
Designed Lifetime: 250,000 burner startup cycles, corresponding to approximately 10 years of usage under normal operating conditions in heating mode.

Usage Features:

Compatibility: The LMO... series is compatible with oil burners with fans to EN 267 and atomization oil burners of monoblock design to DIN EN 230:2005-10. The LMO44... models are specifically suited for stationary direct-fired air heaters.
Mechanical Design: The housing is made of impact-proof, heat-resistant, and flame-retarding black plastic, featuring a plug-in design that audibly engages in the base. It houses a microcontroller, print relays for load control, an electronic flame signal amplifier, and a lockout reset button with an integrated multicolor signal lamp (LED).
Diagnostics: The integrated multicolor LED provides visual diagnostics for operational status and fault messages. For more detailed service information, an OCI400 interface can be connected, allowing communication with ACS400 / ACS410 PC software or flue gas analyzers.
Safety Features:
- Safety Shutdown: Initiates if mains voltage drops below AC 165 V (for 230 V units) or AC 75 V (for 120 V units). Restart occurs when voltage exceeds AC 175 V or AC 95 V, respectively.
- Lockout: Occurs immediately if a fault is detected, deactivating fuel valves, burner motor, and ignition equipment. The red signal lamp illuminates.
- Extraneous Light Detection: Prevents startup and initiates lockout if extraneous light is detected during prepurge or waiting times.
- Flame Loss Detection: Triggers lockout if no flame is established by the end of the safety time (TSA) or if the flame is lost during operation (after a maximum of 3 repetitions).
- Time Supervision Oil Preheater: Initiates lockout if the oil preheater's release contact does not close within 10 minutes.
Reset Functionality: The burner control can be reset by pressing the lockout reset button for 1-3 seconds, provided all contacts in the line are closed and there is no undervoltage.
Electrical Connection: High-voltage ignition cables must be run separately, maintaining maximum possible distances from the unit and other cables. Switches, fuses, and earthing must comply with local regulations. External mains voltage should not be fed to the control outputs. Live and neutral conductors must not be mixed up.
Flame Detector Connection: Detector cables should not be run with other cables to ensure disturbance-free signal transmission. A separate cable is recommended, and maximum permissible lengths must be observed.

Maintenance Features:

Commissioning and Maintenance Checks: Specific safety checks are required during commissioning and maintenance, including burner startup with a darkened flame detector, startup with extraneous light, and operation with simulated flame loss.
Service Adapters: KF8885, KF8833, and KF8840 service adapters are available for checking burner control functions, program indication, simulating flame signals, and measuring flame detector current or resistance.
Remote Lockout Reset: Extension buttons (AGK20.19, AGK20.43, AGK20.55) are available for remote lockout reset.
Disposal: The unit contains electrical and electronic components and must be disposed of in accordance with local and currently valid legislation, not with domestic waste.

Warning Notes:

The unit must not be opened, interfered with, or modified.
All activities must be performed by qualified staff.
Before wiring changes, the plant must be completely isolated from the mains supply.
Adequate protection against electric shock hazard must be provided for the burner control's connection terminals.
Wiring must be checked for orderly state and safety after any work.
The lockout reset button should only be pressed manually, without tools or pointed objects.
Units that have experienced a fall or shock must not be put into operation, even if they show no visible damage.
When replacing LOA26... or LOA36... controls, any ARK21... remote lockout reset modules or similar modules must be removed.
Condensation, ice formation, and water ingress are not permitted, as this can lead to loss of safety functions and electric shock.