Description

The BENTLY 3500/22 288055-01 is a dual-channel relay output module designed for the Bently Nevada™ 3500 machinery protection system—a globally recognized platform for continuous monitoring and automatic shutdown of critical rotating equipment in power generation, oil & gas, and heavy industry. As an integral component of the 3500 rack architecture, the BENTLY 3500/22 288055-01 provides eight independent Form C (SPDT) electromechanical relays—four per channel—that translate alarm and trip conditions from vibration, position, speed, or temperature monitors into hardwired control signals for ESD systems, turbine governors, or plant DCS.

Engineered to meet API 670 standards and certified to SIL 2 per IEC 61508, the BENTLY 3500/22 288055-01 supports flexible logic configurations including 1oo1, 1oo2, or 2oo2 voting between its two channels, enabling users to balance safety integrity against operational availability. Each relay is rated for 2 A at 30 V DC or 250 V AC, suitable for direct interfacing with auxiliary contactors, solenoid valves, or alarm panels without intermediate relays. The module features front-panel LEDs for real-time status indication and supports hot-swap replacement within a powered 3500 rack—minimizing downtime during maintenance. With its robust design and seamless integration into the 3500 ecosystem, the BENTLY 3500/22 288055-01 ensures reliable, auditable, and fail-safe actuation when machinery health deteriorates beyond safe limits.

Technical Specifications

Main Features and Advantages

Fail-safe relay architecture for critical trips:
The BENTLY 3500/22 288055-01 uses electromechanical relays with force-guided contacts—ensuring that if a normally open (NO) contact welds shut, the normally closed (NC) contact cannot close, providing positive feedback for safety validation. This meets stringent requirements for machinery protection in refineries and power plants.

Flexible voting and redundancy support:
Each of the two channels can be independently configured to respond to alarms from any combination of 3500 input modules (e.g., 3500/42 vibration, 3500/25 speed). The BENTLY 3500/22 288055-01 supports cross-channel voting logic, allowing high-reliability trip schemes such as “trip only if both channels agree” (2oo2) to reduce nuisance shutdowns.

Direct interface to plant safety systems:
With 250 V AC switching capability, the BENTLY 3500/22 288055-01 can directly drive auxiliary shutdown solenoids or DCS digital inputs without external relay panels—simplifying system architecture, reducing wiring errors, and lowering lifecycle costs.

Hot-swap and diagnostic visibility:
The module can be replaced while the 3500 rack remains powered, thanks to controlled inrush current and backplane signaling. Front-panel LEDs indicate power, OK status, and individual relay activation—enabling rapid troubleshooting during commissioning or alarm investigations.

Seamless integration with 3500 software suite:
Configured via Bently Nevada’s System 1 or Rack Configuration Software (RCS), the BENTLY 3500/22 288055-01 allows per-relay assignment to specific alarm levels (Alert, Danger) from any monitored parameter, with full audit trail logging for regulatory compliance.

Application Field

The BENTLY 3500/22 288055-01 is a cornerstone of machinery protection strategies in industries where unplanned downtime or catastrophic failure carries severe safety, environmental, or financial consequences. In gas turbine and steam turbine applications, it executes emergency shutdowns when axial displacement or bearing vibration exceeds API 670 thresholds—triggering fuel cutoff valves and breaker trips via its relay contacts. Similarly, in centrifugal compressors used in LNG plants, the BENTLY 3500/22 288055-01 interfaces with anti-surge control systems to initiate recycle valve opening during surge precursors.

In hydroelectric and nuclear power stations, the module provides redundant trip paths for generator step-up transformer cooling failures or pump cavitation events. Petrochemical facilities deploy the BENTLY 3500/22 288055-01 in reactor agitator monitoring systems, where loss of mixing could lead to thermal runaway. Even in mining conveyor drives and large ID/FD fans, its relays activate local alarms or upstream process holds. Across all these scenarios, the BENTLY 3500/22 288055-01 delivers the electrical isolation, certification pedigree, and deterministic response required for mission-critical machinery protection.

Related Products

• BENTLY 3500/20: Rack interface module—required for communication with 3500/22 288055-01

• BENTLY 3500/25: Speed monitor module—often sources trip signals to 3500/22 288055-01

• BENTLY 3500/42: 4-channel vibration monitor—primary input source for relay actions

• BENTLY 3500/15: Power supply module—provides redundant power to 3500/22 288055-01

• BENTLY 3500/32: 4-channel relay module (older)—3500/22 288055-01 offers enhanced diagnostics

• BENTLY 3500/50: Process variable monitor—can trigger 3500/22 288055-01 on temperature/pressure alarms

• BENTLY 3500/92: Communications gateway—enables remote access to 3500/22 288055-01 status

• BENTLY 133396-01: Ribbon cable—connects 3500/22 288055-01 to terminal blocks

Installation and Maintenance

Pre-installation preparation: Before inserting the BENTLY 3500/22 288055-01 into the 3500 rack, confirm that the chassis backplane is powered and that a valid 3500/20 or 3500/94 interface module is installed. Verify that field wiring to terminal blocks uses 18–22 AWG stranded wire with ferrules, and that relay loads do not exceed 2 A per contact. Ensure firmware versions across the rack are compatible—older 3500/20 modules may require upgrade to support full 3500/22 288055-01 functionality.

Maintenance recommendations: Although solid-state in logic, the BENTLY 3500/22 288055-01 contains mechanical relays with finite life (~100,000 operations). Review relay operation counts via System 1 software annually. Inspect terminal connections for corrosion or loosening during scheduled outages. If a relay fails to de-energize, replace the entire module—field repair voids safety certification. Keep a spare BENTLY 3500/22 288055-01 on-site with matching hardware revision (check label: Rev X.X). Always perform a functional trip test after replacement to validate end-to-end shutdown logic.