Description

The Bently Nevada 3500/22M Relay Module (part number 288055-01) is a critical output component of the 3500 Machinery Protection System, a globally recognized platform for continuous monitoring and protection of rotating equipment such as turbines, compressors, pumps, and generators. This module provides eight independent, programmable Form C (SPDT) electromechanical relays that translate alarm conditions from vibration, position, speed, or temperature input cards into hardwired trip, warning, or control signals for plant safety systems, DCS interfaces, or local annunciation panels.

Designed for mission-critical applications governed by standards like API 670, the 3500/22M supports both independent channel logic and redundant voting schemes (e.g., 2-out-of-3 logic) to prevent spurious trips while ensuring fail-safe shutdown during genuine machinery faults. Each relay can be individually configured via the 3500 Configuration Software to respond to specific alarm levels (Alert, Danger) from any monitored channel in the rack—enabling flexible mapping such as “Relay 1 = High Vibration on Bearing 3,” or “Relay 5 = Axial Position Trip on Compressor A.”

Housed in a rugged, front-loading module that snaps into the standard 3500 chassis, the 288055-01 features LED status indicators for each relay (energized/de-energized), supports hot-swap replacement in redundant configurations, and includes built-in diagnostics accessible via the Rack Interface Module (RIM) or 3500/92 Communications Gateway. Its robust design meets industrial EMC, surge, and thermal requirements, making it suitable for installation in turbine control panels, offshore platforms, and petrochemical plants.

Technical Specifications

Main Features and Advantages

API 670-compliant protection logic: The 3500/22M is engineered to meet stringent machinery protection requirements in oil & gas, power, and chemical industries. It enables implementation of delayed alarms, latching/non-latching trips, and redundant sensor voting—critical for avoiding false shutdowns in multi-million-dollar processes.

Flexible relay mapping across the entire rack: Unlike fixed-output modules, the 288055-01 can pull alarm data from any input card in the same 3500 rack—including 3500/42 (displacement), /44 (seismic), /61 (speed), or /62 (temperature). This eliminates the need for external logic relays or PLC intervention for basic trip functions.

High-integrity electromechanical contacts: The use of gold-plated SPDT relays ensures reliable switching of both low-level control circuits (e.g., 24 VDC PLC inputs) and higher-power loads (e.g., solenoid valves, motor starters)—without signal degradation over time, unlike solid-state alternatives.

Hot-swap capability in redundant systems: When installed in a dual-redundant 3500 configuration (with two power supplies and RIMs), the 3500/22M can be replaced live without interrupting protection logic—minimizing maintenance downtime in continuous-operation plants.

Application Field

The 3500/22M 288055-01 is indispensable in gas turbine generator sets, where it triggers emergency shutdowns upon excessive shaft vibration or thrust position deviation—protecting multi-stage compressors from catastrophic failure. In ethylene crackers and refineries, it interfaces with ESD (Emergency Shutdown) systems to isolate feed pumps or recycle compressors during bearing overheating events.

In hydroelectric and steam power plants, the module drives trip coils on main stop valves when turbine differential expansion exceeds safe limits. LNG liquefaction trains rely on it to halt BOG (boil-off gas) compressors if journal bearing temperatures spike. Even in wind turbines, legacy 3500 systems use the 3500/22M to disconnect generators during gearbox vibration alarms.

Its ability to provide hardwired, failsafe outputs—independent of network communication or software layers—makes it a cornerstone of functional safety architectures where SIL-rated responses are required without reliance on digital protocols.

Related Products

• 3500/42: Proximitor (displacement) input card – commonly paired with /22M for vibration trips

• 3500/44: Seismic monitor card – for casing vibration protection

• 3500/61: Speed & zero-speed card – for overspeed shutdown logic

• 3500/62: Temperature monitor – for bearing or lube oil temp alarms

• 3500/15: Power supply module (required for chassis operation)

• 3500/92: Communications gateway (Modbus/TCP, Ethernet/IP)

• 3500/32: 4-channel relay module (simpler, non-programmable alternative)

• 3500/50: Touchscreen display for local alarm viewing

• 133397-01: Ribbon cable for internal 3500 backplane connectivity

Installation and Maintenance

Pre-installation preparation:

• Ensure the 3500 chassis has adequate slot space (3 slots wide) and compatible firmware.

• Verify that the Rack Interface Module (RIM) is present and communicating.

• Plan field wiring using shielded, twisted-pair cables; route away from high-voltage AC lines.

• Configure relay logic in 3500 Configuration Software before commissioning—define source channels, alarm types (Alert/Danger), and latch behavior.

Maintenance recommendations:

• Periodically inspect relay contact integrity using a multimeter (check for oxidation or sticking).

• Monitor front-panel LEDs during routine rounds—unexpected de-energization may indicate upstream sensor or logic issues.

• Perform annual functional tests by simulating alarm conditions to verify correct relay actuation.

• Replace the module if relay chatter, delayed response, or LED mismatch is observed.

• Store spares in anti-static packaging at room temperature; avoid high humidity.