Siemens Spare Parts: Buyer's Guide

What Siemens Makes for Combustion and Burner Systems

Siemens is a globally recognized OEM in industrial combustion controls. Its Building Technologies and Process Instrumentation divisions supply the components that keep burners running safely and efficiently. The 3G Electric catalog covers 172 Siemens products organized into six functional categories:

Burner Control Relays: Key Models and Selection Criteria

Burner controls are the largest segment of the Siemens catalog at 3G Electric. These safety-rated sequencing units manage startup, flame supervision, and lockout for gas, oil, and dual-fuel burners. Below is a comparison of representative models available to order:

When selecting a replacement burner control, verify: supply voltage, burner fuel type, number of burner stages, and the flame-detection method already installed on site. The LDU 11 series (Base LDU 11, SKU REL15310) requires a dedicated base unit; the base accepts cable sections from 0.5 mm² to 1.5 mm² and operates from −40 to +60 °C.

Servo Motors and Actuators: Torque, Timing, and Voltage

Siemens SQN and SQM servo motors drive air dampers and gas valves on burner systems. Selecting the wrong torque or rotation time causes poor air/fuel ratio control and can trigger safety lockout. Key catalog models include:

The SQM 53 482A2 features a die-cast aluminum housing with an impact- and heat-resistant plastic cover, making it suitable for demanding plant environments. The SKP 15 000E1 covers a family of models (SKP15, SKP25, SKP55, SKP75, SKL25) for gas and air valves including biogas and hot-air applications; the SKL25 variant has a closure time of 3–6 s. The AGA 65 connector (SKU SER22006) is the mating connector accessory for compatible servo motor models — confirm the connector type before ordering.

UV Flame Detectors: QRA Series

Flame supervision is a safety-critical function. Siemens QRA-series UV flame probes are designed to work in conjunction with LFL and LME burner control relays.

• QRA 4U (SKU REL15224): UV flame detector, model QRA4.U, rated IP54, Safety Class II (double-insulated). Suitable for gas and oil flame supervision and ignition spark proving. Mounting position is optional.
• QRA 2 / Flange and Socket (SKU REL15205): UV flame probe compatible with QRA2, QRA10, and QRA5 (D and G series). Used for gas and oil burner flame monitoring. Article number BPZ:QRA53.E27 for the flange/socket accessory.

When replacing a UV cell, check the existing probe model stamped on the body and confirm compatibility with the installed burner control relay before ordering.

How to Identify the Correct Siemens Part Number

1. Read the nameplate or label on the existing component. Siemens model numbers are typically stamped or printed directly on the housing (e.g., LFL 1.635, SQN 30 111A3500).
2. Note the full alphanumeric string including suffix characters — different suffixes indicate different voltage ratings, timing configurations, or accessory options.
3. Confirm supply voltage from the nameplate. Many Siemens controls are available in both 220–240 V~ and 100–110 V~ variants; ordering the wrong voltage will damage the unit.
4. Identify the flame-detection method in use (UV probe QRA, ionization, QRB, or QRC) to ensure the replacement control relay is compatible.
5. Cross-reference with the 3G Electric catalog SKU (e.g., REL15122 for LFL 1.635) when submitting a request for quotation.
6. Specify quantity and site location so lead time and logistics can be confirmed accurately at quotation stage.

Compatibility Basics: Avoiding Common Ordering Mistakes

• Burner control relays are not universally interchangeable — LFL, LME, and LMO series serve different burner types and fuel configurations.
• The LDU 11 base (SKU REL15310) is a separate item from the LDU 11 relay modules (REL15141, REL15142); both must be ordered if replacing a complete assembly.
• Servo motor torque must meet or exceed the actuator load requirement of the damper or valve; undersizing causes stall and premature failure.
• Rotation time (90° travel) must match the burner control's timing expectations — the SQN 30 series runs at 4.5 s for 90°, while the SQM 53 482A2 is adjustable from 10 s to 90 s.
• The AGA 65 connector (SKU SER22006) must be verified against the servo motor's connection type before ordering.
• External fuse ratings matter: LDU 11 models specify a maximum 10 A slow-blow external fuse and an internal T6.3H250V fuse per DIN EN 60127.

How to Source Genuine Siemens Parts Through 3G Electric

3G Electric is an authorized distributor supplying genuine Siemens combustion-control components to plant engineers and procurement teams globally. All items are available to order; lead time is confirmed at the quotation stage. 3G Electric manages international logistics and customs clearance, so procurement teams outside the OEM's direct distribution network can access the full catalog range.

To request a quotation, provide the exact Siemens model number (including full suffix), required quantity, and your site's supply voltage. Where a part number is unknown, the 3G Electric technical team can assist with cross-referencing from the installed equipment's nameplate data.

Frequently Asked Questions

What categories of Siemens products does 3G Electric supply?

3G Electric lists 172 Siemens products across six categories: Burner Controls (96 products), Servo Motors (45), Gas Regulation (14), Spare Parts (11), Ignition Transformers (5), and Valve/Solenoid (1). All are available to order with lead time confirmed at quotation.

How do I tell the difference between LFL, LME, and LMO burner control relays?

LFL relays (e.g., LFL 1.635, LFL 1.122) support gas, oil, or dual-fuel burners with air damper control. LME relays (e.g., LME 21 350C2) target gas or gas/oil single- or two-stage burners. LMO relays (e.g., LMO 64 301.C2) are dedicated to intermittent-operation oil burners. Always match the relay series to your burner fuel type and stage configuration.

What is the LDU 11 base unit and do I need it separately?

Yes. The LDU 11 base (SKU REL15310) is a separate mounting and wiring base for LDU 11 relay modules. It accepts cable sections from 0.5 mm² to 1.5 mm² and operates from −40 to +60 °C. Order both the base and the relay module if replacing a complete assembly.

Which Siemens servo motor should I choose for a high-torque damper application?

The SQM 53 482A2 (SKU SER20004) delivers up to 40 Nm with an adjustable rotation time of 10–90 s, making it suitable for larger dampers. For lighter-duty applications, the SQN 30 series provides 1–1.5 Nm nominal torque with a fixed 4.5 s rotation time for 90°. Match torque to your actuator load requirement.

Can I use a QRA 4U UV cell with any Siemens burner control relay?

Not automatically. The QRA 4U (SKU REL15224) is compatible with burner controls that support UV probe input — such as LFL and LME series relays. Verify that your installed control relay specifies QRA-type UV probe compatibility before ordering a replacement cell.

Are Siemens parts available for international delivery?

Yes. 3G Electric handles international logistics and customs clearance for orders worldwide. All Siemens items are available to order; lead time and shipping details are confirmed at the quotation stage. No specific origin city or carrier is quoted in advance.

How do I find the correct part number if the label on my unit is damaged?

Check any associated wiring diagrams, commissioning records, or burner manufacturer documentation for the original part number. Alternatively, provide the burner make, model, fuel type, supply voltage, and a description of the component to 3G Electric's technical team for cross-reference assistance.

What fuse specification does the LDU 11 323A27 require?

The LDU 11 323A27 (SKU REL15141) requires a maximum 10 A slow-blow external fuse and an internal T6.3H250V fuse rated to DIN EN 60127. Always replace fuses with the specified type and rating to maintain the safety integrity of the gas valve proving circuit.