Description
Fireye 25SU3-2000 Flame Safeguard Amplifier
Product Overview
The Fireye 25SU3-2000 is a rack-mounted Flame Safeguard Amplifier designed to determine the presence or absence of burner flame while distinguishing the pulse characteristics generated by compatible Fireye flame scanners. It belongs to the 25SU3 family and uses a 19-inch rack architecture, with the amplifier operating from either 24 VAC or 24 VDC. Fireye documentation identifies two scanner inputs, allowing scanner A, scanner B, or both scanners to be incorporated into the programmed operating arrangement.
Rather than acting as a generic analog input card, the Fireye 25SU3-2000 performs dedicated flame-signal processing for burner management. Its dynamic input range reaches 1,900 pulses per second, matching the output range of the specified Fireye scanners. Two selectable scanner logic programs are available, and an external dry-contact input can switch between the programmed options. This architecture allows the same amplifier to be configured for different burner or scanner operating requirements without treating the device as ordinary PLC signal conditioning.
For engineers maintaining older boiler, furnace, process-heating, or turbine-related combustion systems, the Fireye 25SU3-2000 is important because the flame relay and marginal alarm functions sit directly within the burner safeguard chain. The unit provides a scalable 4–20 mA representation of flame signal for supervisory monitoring while retaining dedicated relay outputs for flame-status and marginal conditions. Remote communication to a PLC is also documented through Allen-Bradley DF1 or Modbus capability, but the exact communication arrangement should be confirmed against the installed system.
Product Introduction
Flame detection is one of those applications where a generic replacement can create a commissioning problem very quickly. The 25SU3-2000 does more than amplify a scanner signal: it evaluates scanner pulse behavior, applies programmed flame thresholds and response timing, and drives dedicated flame-safeguard outputs.
For a burner-management system upgrade or legacy replacement, confirm the scanner type, rack arrangement, power supply, programmed scanner option, relay wiring, and communications method. Fireye lists compatible scanner families including the 45UV5 and 45RM4 in the 25SU3-2000 application documentation.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Product Model | 25SU3-2000 |
| Manufacturer | Fireye |
| Product Series | 25SU3 |
| Product Type | Rack-mounted Flame Safeguard Amplifier |
| Mounting Format | 19-inch rack / Eurocard-style architecture |
| Supply Voltage | 24 VAC or 24 VDC |
| Scanner Inputs | 2 |
| Scanner Designations | Scanner A and Scanner B |
| Maximum Pulse Input | 1,900 pulses/second |
| Scanner Selection | Scanner Option 1 / Scanner Option 2 |
| Option Selection Input | External dry contact |
| Flame Relay | One DPDT/Form C flame relay arrangement |
| Marginal Alarm Relay | One SPDT/Form C relay |
| Analog Output | 4–20 mA, current sourcing |
| Analog Output Load | Up to 1,000 Ω |
| Flame Failure Response Time | Adjustable, 1–6 seconds |
| Flame Relay Delay-On Time | Adjustable, 0–10 seconds |
| User Interface | Keypad and 8-character alphanumeric display |
| Security | Password protection for programmed parameters |
| Status Indication | Front-panel LED |
| Communications | PLC communication capability; Allen-Bradley DF1 or Modbus documented |
| Height | 5.06 in / 128.5 mm |
| Depth | 7.0 in / 203.2 mm |
| Front-Panel Width | 1.98 in / 50.3 mm |
| Front-Panel Thickness | 0.0625 in / 1.588 mm |
| Full Rack Capacity | Up to 8 amplifiers |
| Half Rack Capacity | Up to 4 amplifiers |
The dimensions, scanner-input arrangement, pulse range, relay configuration, timing ranges, analog output, and rack capacity are documented in Fireye bulletin CU-34E.
25SU3-2000
Major Features / Practical Advantages
Dual Flame Scanner Processing
Two independent flame-scanner inputs are available. The amplifier can evaluate scanner A, scanner B, or a combination according to the programmed scanner option. This is useful where burner installations require different scanner-selection logic without installing a separate signal-processing amplifier for every scanner arrangement.
The important maintenance point is scanner compatibility. The 25SU3-2000 expects the pulse characteristics associated with its intended Fireye scanner family. Replacing the scanner with a physically similar detector does not establish functional compatibility.
1,900 Pulse/Second Dynamic Range
Fireye specifies a dynamic range of 1,900 pulses per second. The range corresponds to the output characteristics of compatible Fireye flame scanners and allows the amplifier to discriminate between scanner pulse behavior rather than merely treating flame detection as a simple binary contact.
This is also why the 25SU3-2000 should not be replaced by a generic PLC high-speed input without reproducing the actual flame-safeguard logic and response characteristics.
Adjustable Flame-Failure Response
The amplifier provides an adjustable Flame Failure Response Time from 1 to 6 seconds. Independent flame-relay delay-on timing is also configurable from 0 to 10 seconds. These settings directly affect burner-management behavior and therefore should be recorded before replacing an installed unit.
Do not assume that a replacement unit should be left at factory defaults. Existing commissioning parameters can be part of the approved burner-control sequence.
4–20 mA Flame Signal
A current-sourcing 4–20 mA analog output provides a scalable representation of the flame signal. The documented maximum connected load is 1,000 Ω. This output can be routed to a PLC, DCS, recorder, or HMI for supervisory indication without making the supervisory controller responsible for the primary flame-detection function.
Dedicated Flame and Marginal Relays
The 25SU3-2000 provides dedicated relay contacts for flame status and marginal alarm conditions. That distinction matters in burner-control wiring: a marginal flame indication does not necessarily represent the same condition as a confirmed flame failure.
When replacing the amplifier, terminal assignments and relay contact logic should be compared against the existing wiring drawings rather than relying solely on the model number.
Keypad and Password Protection
The front panel provides keypad entry, an eight-character alphanumeric display, LED status indication, and password protection for programmed parameters. This allows operating thresholds and timing parameters to be configured locally while limiting unauthorized modification.
PLC Communication Capability
Fireye documentation describes remote communication capability to a PLC using Allen-Bradley DF1 or Modbus. The exact implementation should be verified against the application because communication support does not mean that every installation uses both protocols simultaneously.
Related Products
- 25SU3-2100 — Related 19-inch rack-mounted flame safeguard amplifier with 24 VAC/DC operation and FM approval; verify certification and configuration before substitution.
- 25SU3-2150 — 25SU3 amplifier variant with higher noise immunity and CE/FM approval.
- 45UV5-1101 — Fireye ultraviolet flame scanner compatible with documented 25SU3-2000 applications.
- 45RM4-1003 — Fireye infrared flame scanner used with the 25SU3-2000 family.
- 60-2470-1 — 110 VAC power supply associated with the 25SU3-2000 rack system.
- 60-2470-2 — 220 VAC power supply associated with the 25SU3-2000 rack system.
- 60-2471-1 — Half-rack mounting arrangement for 25SU3 amplifier systems.
- 60-2471-3 — Full 19-inch rack for 25SU3 amplifier systems.
- 60-2530 — Surface-mount wiring rack designed for 25SU3-2000/2100 amplifier systems. Fireye documentation confirms compatibility with the 25SU3 amplifier family.
- 19UVPS-2120 — 120 VAC power supply module for compatible high-voltage Fireye scanner arrangements.
- 19UVPS-2220 — 220 VAC version of the 19UVPS power supply family.
FAQ
What is the Fireye 25SU3-2000 used for?
It is a Flame Safeguard Amplifier used to detect and evaluate flame signals in single- or multi-burner installations. It processes pulse signals from compatible Fireye scanners and provides flame-status, marginal-alarm, and analog flame-signal outputs.
Is 25SU3-2000 a PLC input module?
No. It is dedicated combustion-safety equipment. A PLC or DCS may receive its analog or communication data, but the 25SU3-2000 performs the flame-signal processing and drives its dedicated safeguard relay outputs.
Can I connect two flame scanners?
Yes. Fireye documents two scanner inputs, A and B. The amplifier can use either scanner separately or both according to the selected scanner option.
Can I hot-swap the 25SU3-2000?
Do not assume hot-swapping is permitted. This equipment is part of a burner flame-safeguard system. Fireye’s related power-supply documentation specifically warns against removing or installing certain power-supply modules with power applied because equipment damage can result. Replacement should therefore follow the approved burner-management shutdown and electrical-isolation procedure.
What is the flame failure response time?
The documented adjustable Flame Failure Response Time is 1 to 6 seconds. The actual installed setting should be checked against the burner-management design and commissioning records.
Does 25SU3-2000 provide a 4–20 mA output?
Yes. It provides one current-sourcing 4–20 mA analog output for the flame signal, with a documented maximum connected load of 1,000 Ω.
Does it support Modbus?
Fireye documentation states that the amplifier provides remote PLC communication capability using Allen-Bradley DF1 or Modbus. The actual protocol and communication hardware in an installed system should be verified before assuming a particular PLC interface.
Is 25SU3-2000 the same as 25SU3-2100?
No. They are closely related 25SU3 amplifier models, but their approval/configuration differences matter. The 25SU3-2000 is documented as the CE-approved 19-inch rack amplifier, while the 25SU3-2100 is listed separately with FM approval. Treat the exact model number as significant when replacing equipment.
What should I verify before buying a replacement?
Verify the exact 25SU3-2000 model, scanner type, scanner wiring, installed rack, power-supply module, programmed scanner option, flame-failure response time, relay logic, 4–20 mA scaling, and communication interface. For a New Surplus or refurbished unit, request clear nameplate photographs and functional test evidence. A visually clean amplifier does not prove that its flame relay, scanner input circuitry, display, or stored parameters are suitable for service.
Procurement Note
The Fireye 25SU3-2000 should be purchased as a combustion-control component, not as a generic signal amplifier. The scanner technology and programmed flame-detection parameters are just as important as the amplifier’s physical form factor.
For a replacement project, record the existing scanner model, flame-failure response time, relay wiring, scanner-option configuration, analog scaling, communication protocol, and rack/power-supply arrangement before removing the installed unit. If the application is safety-critical, perform a controlled burner-management functional test after replacement rather than treating successful power-up as acceptance.
Fireye’s CU-34E documentation should remain the primary reference for the amplifier’s detailed installation, configuration, and operating requirements.
