Triconex 3511 vs Istec SpeedSys®300
In turbomachinery, overspeed protection is critical to preventing failure and ensuring compliance. To help you come to the best decision in choosing the right system, we’ve put out a comparison. In this comparison, we’ll be looking at the Triconex 3511 and the SpeedSys 300.
Why forward-thinking OEMs, integrators, and end users choose SpeedSys® 300
Established brands usually work with what’s already there for many years, not taking into account customer feedback and improvement points. Istec however, has built new systems from scratch to fulfill all your current day needs in machine protection and monitoring.
Triconex 3511
Istec SpeedSys 300
Certified-by-design
Triconex 3511 is designed for critical turbomachinery applications and has extensive operational use in overspeed protection systems, including API 670‑based installations.
Certified-by-design
The SpeedSys® 300 is certified-by-design, with functional safety requirements embedded directly into the system architecture. SIL 2 and SIL 3 capability are integral to the product design rather than added later.
(Background on this approach: The difference between SIL certification by design and proven in use — Istec)
Standalone protection concept
Overspeed (and optional acceleration) protection is implemented within a single, integrated system architecture
Standalone protection concept
The system operates as an independent safety layer, separating overspeed protection from control and monitoring functions.
Modular redundancy approach
The Triconex 3511 approaches redundancy in an internal way, with voting likewise inherent to the system architecture.
Modular redundancy approach
Designed for SIL3 applications, but able to be scaled back to any type of application, from multi-module voting structures to stand-alone configurations.
Integrated safety I/O
The system provides internally voted shutdown relay outputs, individual alarm relays per module, and 4–20 mA speed outputs for direct connection to trip valves and monitoring systems.
Integrated safety I/O
Able to perform a complete overspeed function independently of any racks, software platforms, or external logic.
Compact and practical design
The Triconex 3511 is not built to fit into compact spaces and retrofit projects.
Compact and practical design
Its compact footprint fits space‑constrained installations and retrofit projects, while maintaining full overspeed protection functionality within a single module.
Communication for diagnostics
The Triconex 3511 uses MODBUS integration to communicate monitoring and diagnostics.
Communication for diagnostics
Modbus RTU over RS‑485 is provided for monitoring and diagnostics.
Standalone and distributed installation
The Triconex 3511 operates as a complete, self‑contained overspeed protection system, with protection, voting, and trip functions implemented at system level rather than as independent standalone modules.
Standalone and distributed installation
The SpeedSys® 300 is installed as a standalone device, mounted individually in a control or protection panel. Multiple SpeedSys units can be installed side‑by‑side to implement redundancy concepts, without requiring a shared rack, backplane, or central baseplate.
Lifetime Support
SpeedSys 300 delivers a clean architectural separation between control and trip logic ensuring uncompromised protection compared to integrated systems.
SIL3 by Design
Adapt as needed: from single-channel setups to fully redundant 2oo3 architectures, SpeedSys 300 supports stepwise scalability at every stage.
Compact Footprint
Engineered for space-limited panels and demanding environments, it’s ideal for both retrofits and new installations.
| Aspect | Triconex 3511 | Istec SpeedSys® 300 |
|---|---|---|
| Key features | Speed signal acquisition and conditioning, able to interface speed sensors with the Tricon safety system | Overspeed, underspeed, and acceleration protection, SIL2/3 capability, safety relays and safety analog output, external voting, Modbus RS-485 |
| Number of relays | No relays, only speed input channels | 2 safety relays (DPST), 2 non-safety relays (SPST) |
| Frequency range | 1000 Hz to 20 kHz | 0.025 Hz to 35 kHz |
| Hardware response time | < 25 ms | < 8 ms |
| Number of inputs (active) | Two speed inputs, no other information listed | 1 input per module (only one sensor input active at a time) |
| Voting system | Dependent on what Tricon system is used | 1oo1 (single module); 1oo2 or 2oo3 using multiple modules (external voting) |
| Outputs | Two outputs, no information listed | • 1 × safety‑rated 4–20 mA analog output • 1 × binary output • 1 × frequency output • Modbus RTU (RS‑485, diagnostics only) |
| Input voltage | 24 VDC | 24 VDC (18 – 36 VDC), dual-redundant power supply |
| Functional safety | No information listed | SIL 2 / SIL 3 capable; functional safety embedded in system design |
| Stand-alone protection | Complete overspeed protection, but not independently of a system | Yes – each module performs a complete overspeed protection function independently |
| Relay information | No relays, only speed input channels | 2 safety relays (DPST), 2 non-safety relays (SPST), 1 safety 4-20 mA analog output, 1 frequency output, up to 30 VDC maximum switching capacity. Binary input/output and Modbus RS-485 |
| Rack / backplane mounting | Not listed | Optional 19‑inch rack for mechanical mounting only; no shared backplane or internal bus |
| Reverse scalability | Not listed | Scalable from single module (SIL 2) to redundant |
FAQ
Yes, the SpeedSys® 300 is an independent overspeed protection system with its own safety outputs.
Yes, both systems support redundant architectures, though only the SpeedSys® 300 is able to do so without the support of an additional system.
No, overspeed logic is executed at the Tricon system level, not within the 3511 module itself.
Accuracy disclaimer
All of our comparison pages have been filled in to the best of our knowledge, using publicly available sources. However, we cannot guarantee that they are fully up-to-date or completely correct.
Istec ensures the availability and safety of your rotating machinery by providing the most convenient and accessible hardware solutions, delivered by the world’s leading vibration and speed sensing experts.