Introduction: The Evolution of Flame Safety
For decades, industrial burners have demanded ever more reliable flame supervision. Early systems relied on simple UV tubes, but modern processes require intelligent scanning that can discriminate between true flame and background radiation. The 95DSS3-1 InSight II Scanner from Yokogawa represents this evolution—a compact, rugged solution engineered for continuous duty in harsh environments.
Built on proven optical sensing technology, this scanner delivers precise flame presence detection while withstanding temperature extremes, humidity, and vibration. Its cast aluminum housing with gray polyester powder coat finish protects internal electronics, ensuring long service life even in demanding boiler and furnace applications.
Key Features & Technical Specifications
The 95DSS3-1 is packed with features that simplify installation and enhance reliability:
- Dual flame relays: Two SPDT relays (N.O. and N.C.) provide redundant flame status outputs.
- Fault relay: A dedicated SPST (N.O.) relay signals system faults for immediate operator awareness.
- Quick-disconnect connections: 12-pin male on the right side (for 59-547-xx cable) and 8-pin male on the left (for 59-546-xx cable) simplify field wiring.
- Wide operating temperature: Rated from -40°F to +150°F (-40°C to +65°C) ambient, with internal tolerance up to 176°F (80°C).
- Storage resilience: Survives -40°F to +185°F (-40°C to +85°C) storage conditions.
- Humidity resistance: Operates in 0% to 95% relative humidity, non-condensing.
- Contact rating: Maximum 100 mA @ 30 Vdc or 100 mA @ 50 Vac (-1 versions).
- Power input: 24 Vdc (+10%/-15%), 0.35 A, 8.5 VA, with 20 msec minimum hold time.
One standout feature is the dual quick-disconnect design. This allows pre-wiring of cables before mounting the scanner, reducing downtime during replacement or maintenance. The screw-type connectors ensure secure, vibration-resistant terminations.
Applications & Use Cases
The 95DSS3-1 is ideal for flame supervision in industrial boilers, furnaces, and incinerators. Its NEMA Type 4X / IP66 rating makes it suitable for outdoor installations or washdown areas. Class I Division 2, Groups A, B, C & D and Class II Division 2, Groups F & G approvals (refer to agency approvals table) allow use in hazardous locations.
In a typical burner management system, the scanner mounts on the burner sight pipe and continuously monitors the flame. The dual relay outputs can be wired to a PLC or burner control to initiate fuel shutoff on flame loss. The fault relay provides diagnostic feedback, enabling predictive maintenance.
Furthermore, the wide operating temperature range ensures reliable performance in both frigid northern climates and tropical processing plants. The non-condensing humidity tolerance prevents moisture-related false trips.
Installation & Setup
Proper installation is critical for optimal scanner performance. The 95DSS3-1 requires a threaded mounting flange, ordered separately. For fiber optic mounting, refer to bulletin CU-117.
When installing, ensure the scanner's viewing window is aligned with the flame and free from obstructions. Use the provided quick-disconnect cables (59-547-xx for right side, 59-546-xx for left side) to connect power and signal wiring. The screw-type connectors should be tightened to manufacturer specifications to prevent loosening from vibration.
Power supply: A 24 Vdc source with +10%/-15% tolerance is required. The supply must maintain at least 20 msec hold time to prevent nuisance shutdowns during momentary power dips. Yokogawa recommends the Fireye power supply 60-2685 for reliable operation.
Maintenance & Reliability
Routine maintenance is straightforward. Periodically inspect the scanner lens for dirt or contamination, as buildup can attenuate the optical signal. Clean the lens only with a soft, dry cloth—never use solvents that could damage the coating.
Check all electrical connections for tightness and signs of corrosion. The cast aluminum housing is designed to withstand harsh environments, but ensure gaskets remain intact to maintain the IP66 rating.
Given the scanner's robust construction, typical service life is extensive. However, like all optical devices, the sensor may degrade over time. If flame response becomes sluggish, verify the lens condition and alignment before replacing the unit.
Compatibility & Integration
The 95DSS3-1 is designed to work with Yokogawa's InSight II system. The relay outputs are dry contacts, compatible with most PLCs and burner control systems. The fault relay can be wired to an alarm annunciator for immediate operator notification.
For replacement applications, the 95DSS3-1 can often substitute older scanners with similar mounting and electrical characteristics. Always verify compatibility with existing cabling and control logic before retrofitting.
Troubleshooting & Common Issues
If the scanner fails to detect flame, check the following:
- Lens cleanliness and alignment
- Power supply voltage and hold time
- Cable connections (both 8-pin and 12-pin)
- Relay wiring and logic configuration
If the fault relay activates, it may indicate an internal error or a wiring fault. Consult the official Yokogawa documentation for detailed diagnostics.
Product Support & Availability
The 95DSS3-1 is available from AutoDCSTech. Contact our team to verify current lifecycle status and availability before ordering. We are committed to helping you maintain safe and efficient burner operations.
