Siemens LME7 Series Industrial Burner Controllers

Siemens LME7 Series comprises microprocessor-based burner controls for medium- to large-capacity industrial gas and oil burners. Designed for multistage and modulating forced-draft burners and compatible atmospheric gas burners, the series provides automatic startup sequencing, flame supervision, air pressure monitoring, and safety control in intermittent operation. LME71 offers parameter-dependent PWM fan control, while LME72 and LME73 support actuator control. Flame detector compatibility varies across LME71, LME72, and LME73. The controllers support PME7 program modules and parameterization through Siemens AZL2 or ACS410, making them suitable for industrial boilers and process heating equipment.

Product Description

Siemens Burner Controllers LME7 Series

Siemens Burner Controllers LME7 Series are microprocessor-based industrial burner controls developed for automatic startup, flame supervision, and safety management of medium- to large-capacity gas and oil burners.

The LME7 Series supports multistage and modulating forced-draft burners as well as compatible atmospheric gas burners in intermittent operation. Its operating functions include burner program sequencing, air pressure supervision, undervoltage detection, and safety lockout.

The family includes LME71, LME72, and LME73. Depending on the model and the selected PME7 program module, the controllers support mechanical or pneumatic fuel-air ratio systems, air damper actuator control, and PWM fan operation.

Key Features

  • Microprocessor-based burner control with digital startup sequencing
  • Suitable for multistage and modulating industrial burners
  • Flame supervision with compatible ionization probes or optical flame detectors
  • Air pressure switch monitoring and functional checks
  • Integrated undervoltage detection
  • Electrical remote lockout reset
  • Three-color LED for operating status and fault diagnostics
  • Parameter configuration through Siemens AZL2 or ACS410 software
  • Interface for compatible PME7 program modules
  • Three-digit 7-segment display on LME71 and LME73
  • PWM fan control on supported LME71 configurations
  • Actuator control output on LME72 and LME73

Siemens LME7 Model Differences

Series Key Functions Flame Supervision
LME71 Digital burner sequencing and parameter-dependent PWM fan control Ionization Probe / QRA2 / QRA4 / QRA10
LME72 Burner sequencing with actuator control output Ionization Probe
LME73 Burner sequencing with actuator control and broader optical flame detector compatibility Ionization Probe / QRA2 / QRA4 / QRA10 / QRB1 / QRB3 / QRB4; QRC on supported variants

Control and Communication

The controller uses a compatible PME7 program module to define burner operating functions and sequences. Parameter configuration and diagnostics are available through Siemens AZL2 or ACS410 using suitable interface accessories.

Depending on model and configuration, the system can support analog load control signals, air damper positioning, or PWM fan operation. These features are model-specific and must not be assumed to be available on every LME7 controller.

Industrial Applications

  • Industrial steam and hot water boilers
  • Industrial oil burner systems
  • Industrial gas burner systems
  • Forced-draft combustion equipment
  • Industrial furnaces and process heating systems
  • Multistage and modulating burner installations

Product Selection Guidelines

Verify the supply voltage, fuel type, flame detector compatibility, required actuator or PWM fan functions, load control inputs, wiring arrangement, and compatible PME7 program module before selecting an LME71, LME72, or LME73 controller.

Important: The basic LME7 unit has an IP00 protection rating. The burner or boiler manufacturer must ensure appropriate IP40 installation protection. Commissioning and safety-related parameter changes must be performed by qualified personnel according to Siemens technical documentation.

Specifications

Siemens LME7 Series Technical Specifications

Specification Technical Data
Brand Siemens
Product Series LME7 Series
Models LME71 / LME72 / LME73
Product Type Microprocessor-based Burner Control
Burner Application Multistage / Modulating Forced-Draft Burners and Compatible Atmospheric Gas Burners
Fuel Type Oil / Gas, depending on configuration
Operating Mode Intermittent Operation
Supply Voltage 120 V AC or 230 V AC, depending on model
Supply Frequency 50 / 60 Hz
Internal Power Consumption Typically <10 W
External Primary Fuse Max. 6.3 A, slow-blow
Flame Detection LME71: Ionization / QRA2 / QRA4 / QRA10; LME72: Ionization; LME73: Ionization / QRA2 / QRA4 / QRA10 / QRB1 / QRB3 / QRB4, QRC on supported variants
Air Pressure Supervision Air Pressure Switch Monitoring
Analog Load Control Inputs 0-10 V DC, 0/4-20 mA, 0-135 Ohm on supported models
Fan Control PWM Control Output on supported LME71 configurations
Actuator Control Control output on LME72 / LME73
Program Module Compatible Siemens PME7 Series
Parameter Adjustment AZL2 / ACS410
Status Indication 3-Color LED; 3 x 7-Segment Display on LME71 / LME73
Flame Failure Response Time Max. 1 s, subject to detection configuration
Operating Temperature -40 to +60 °C
Storage Temperature -40 to +70 °C
Relative Humidity <95% RH
Degree of Protection IP00 (Basic Unit); IP40 installation protection required
Weight Approx. 490 g
Installation Altitude Max. 2,000 m above sea level
Designed Lifetime 250,000 burner startup cycles or approx. 10 years under specified conditions
Applicable Standards DIN EN 298, DIN EN 1643, DIN EN 13611, DIN EN 60730-2-5
Technical Reference Siemens CC1N7105en (18.01.2024)

LME7 Model Comparison

Model Voltage UV QRA QRB QRC Actuator Control PWM Fan
LME71.000A1 120 V AC Yes No No No Supported*
LME71.000A2 230 V AC Yes No No No Supported*
LME71.901A2 230 V AC Yes No No No Subject to configuration
LME72.000A2 230 V AC No No No Yes No
LME73.000A1 120 V AC Yes Yes No Yes No
LME73.000A2 230 V AC Yes Yes Yes Yes No

Technical Note: *PWM fan control requires the applicable PME7 program and parameter configuration. Flame detector options, analog inputs, and actuator functions vary by model. LME71.901A2 and LME72.000A2 may be available on request. Specifications are based on Siemens CC1N7105en. Consult the correct PME7 program module documentation before installation.