Key Technical Specifications
- Product Model: LG1093AC01
- Manufacturer: Honeywell
- Product Type: Ultraviolet (UV) Flame Sensor
- Detection Band: 180–260 nm
- Response Time: ~0.2 seconds
- Operating Voltage: 28 VDC (Range: 20–35 VDC) or 115 VAC
- Operating Temperature: -40°C to +85°C
- Max Transmission Distance: 330 meters (to amplifier)
- Protection Rating: NEMA 4X / IP66 (Typical for series)
- Typical Applications: Gas Turbines, Industrial Boilers, Furnaces
Product Introduction
Honeywell LG1093AC01 is a specialized ultraviolet flame sensor designed to detect the specific 180–260 nm radiation band emitted during hydrocarbon combustion. It serves as the primary safety eye in burner management systems, providing rapid flame verification to prevent fuel accumulation.Unlike standard optical sensors, this unit filters out visible light and infrared interference common in hot industrial environments. The 0.2-second response time ensures the control system can trip the fuel valve almost instantly if flame is lost, meeting critical safety timing requirements for gas turbines and boiler applications. (We often see these fail not from age, but from quartz window fouling—keep the lens clean.)
Installation & Configuration Guide
Preparation (10 min)
Lock out and tag out the burner management system. Verify the 28 VDC supply is stable and within the 20–35 VDC range. Gather a UV simulation lamp or a butane lighter for testing. Ensure the mounting flange is clean and free of old gasket material.Removal (5–10 min)
Disconnect the shielded signal cable first to prevent static discharge. Unscrew the retaining nut or flange bolts. Pull the LG1093AC01 straight out; do not twist, as this can damage the internal tube alignment. Inspect the mounting tube for carbon buildup or refractory damage.Installation (10 min)
Insert the new sensor, ensuring the UV window faces the flame directly. Hand-tighten the retaining nut, then torque to spec (typically 20–30 in-lbs) to maintain the NEMA 4X seal. Reconnect the shielded cable, verifying the shield is grounded at the amplifier end only to prevent ground loops.Power-On & Test (10 min)
Restore power to the BMS. Use a UV test lamp at the sensor window; the flame status LED should illuminate within 0.2 seconds. Block the UV source; the sensor must drop out immediately. Run a full flame simulation test through the burner sequence to verify the amplifier is interpreting the signal correctly.
Troubleshooting Quick Reference
| Symptom | Probable Cause | Corrective Action |
|---|---|---|
| No Flame Signal | Fouled Quartz Window | Clean window with alcohol; inspect for cracks |
| Intermittent Signal | Ground Loop / Noise | Verify single-point shield grounding; check voltage |
| False Flame Signal | Solar/ARC Interference | Check sensor alignment; verify 180-260nm filter |
| Amplifier Fault | Cable Open/Short | Measure cable resistance; check for pinch points |
| Slow Response | Aging UV Tube | Replace sensor; UV tubes degrade over time |
Dimensions, Mounting & Wiring Notes
- Mounting: 1-1/4″ NPT male thread or 4-bolt flange (verify specific suffix)
- Wiring: Use shielded twisted pair; max length 330m to amplifier
- Clearance: Maintain minimum 6 inches from hot refractory to prevent thermal shock to the housing
Quality Transparency Strategy
Incoming Inspection
We verify the Honeywell part number and date code against manufacturer records. Anti-counterfeit checks include inspecting the UV tube glass for proper sealing and checking the housing for casting marks. Physical inspection covers thread condition and window clarity.Live Functional Testing
Each LG1093AC01 is mounted on a dedicated test fixture with a calibrated UV source. We measure the response time to confirm it meets the <0.2s spec and verify the output signal swings correctly at 28 VDC. A 24-hour burn-in cycle checks for thermal drift in the internal amplifier circuit.Electrical Testing
Insulation resistance is verified at >10 MΩ @ 500V. Ground continuity is checked from the housing to the signal ground pin. Hi-pot testing ensures isolation between the high-voltage internal tube and the low-voltage output circuit.Firmware/Revision Verification
We record the hardware revision and manufacturing date code. Internal jumper settings (if applicable for voltage selection) are photographed to ensure they match the 28 VDC or 115 VAC configuration requested.Final QC & Packaging
A QC signature is applied to the test report. The sensor is sealed in an anti-static bag, wrapped in bubble wrap, and packed in a rigid carton to prevent window breakage. A “QC Passed” label with the test date is affixed to the package. Function verified under test conditions.
Technical Pitfall Guide
Voltage Mismatch
The LG1093AC01 series supports both 28 VDC and 115 VAC, but they are not field-convertible. I’ve seen technicians wire a 28 VDC unit to a 115 VAC supply and instantly fry the internal board. Always check the label voltage before applying power.Window Fouling
In dirty boiler environments, carbon and ash coat the quartz window, blocking UV radiation. The sensor isn’t broken; it’s just blind. Schedule regular cleaning based on your fuel quality. If you’re replacing sensors every 3 months, check your combustion tuning or add an air purge kit.Shield Grounding
The 330m cable run acts as an antenna. If you ground the shield at both ends, you create a ground loop that looks like noise to the amplifier. Ground the shield at the amplifier panel only. I’ve spent hours chasing “bad sensors” that were actually just poorly grounded cables.Alignment Issues
UV radiation is line-of-sight. If the sensor is angled more than 45° off-axis, sensitivity drops drastically. During installation, use a laser pointer or alignment rod to ensure the sensor has a direct view of the flame root, not just the glowing refractory.Thermal Shock
Installing a cold sensor directly into a hot furnace can crack the quartz window. Allow the sensor to acclimate to ambient temperature near the furnace before final insertion, or use the air purge connection to cool the window during operation.
FAQ
Is the LG1093AC01 compatible with the LG1093AA24?
They are in the same family but verify the voltage and response time. The AA24 is typically 24 VAC/VDC with a 2s response, while the AC01 is 28 VDC with 0.2s response. Don’t swap them without checking the amplifier specs.I’m getting false flame signals, is the sensor bad?
Probably not. UV sensors can be triggered by welding arcs, lightning, or even strong sunlight if the window is cracked. Check the installation location and window integrity first. I’ve seen welders 50 feet away trip these sensors.Can I clean the quartz window myself?
Yes, use isopropyl alcohol and a lint-free cloth. Never use abrasives or metal scrapers. If the window is etched or pitted, cleaning won’t help; replace the sensor. A scratched window scatters UV light and reduces sensitivity.What’s the max cable length for this sensor?
Honeywell specs say 330 meters (approx. 1000 ft) to the amplifier. Beyond that, signal degradation becomes a risk. If you need longer runs, consider a local signal conditioner or a fiber optic extension kit.I lost the datasheet, where do I find it?
Search “Honeywell LG1093 Series Flame Sensor Installation Manual” on the Honeywell Building Technologies site. Or contact us; we keep PDF copies of legacy flame detection docs since they’re often hard to find.Is this sensor sensitive to sunlight?
The 180–260nm band is solar-blind, meaning the atmosphere blocks most solar UV in this range. However, a cracked window or damaged filter can let visible light in, causing false trips. Always inspect the window for integrity.Do you test with actual fire?
No, that’s unsafe and inconsistent. We use calibrated UV simulation lamps that replicate the 180–260nm spectral output of a hydrocarbon flame. This provides repeatable, quantifiable test results that match OEM performance specs.
