Email: sales@slxytech.com
WhatsApp / Wechat：8617062388866
Phone：+86 17062388866Description
The BENTLY 135785-02A is a critical relay output interface module designed exclusively for the Bently Nevada 3500 machinery protection system—a globally recognized platform for continuous monitoring and safeguarding of high-value rotating equipment such as steam turbines, gas compressors, pumps, and generators. As part of the 3500 series I/O architecture, the BENTLY 135785-02A provides four independent, Form C (changeover) electromechanical relays that translate internal alarm or trip conditions from 3500 monitor cards (e.g., vibration, speed, or position modules) into dry contact signals capable of interfacing directly with plant-wide safety systems, emergency shutdown (ESD) logic solvers, or local annunciators. Each relay is rated for up to 2 A at 30 VDC or 250 VAC, ensuring compatibility with a wide range of control and interlock circuits.
Positioned as a key enabler of functional safety, the BENTLY 135785-02A supports both fail-safe and non-fail-safe configurations through jumper-selectable modes on the module itself. In fail-safe mode, loss of power or module fault forces all relays to their de-energized (safe) state—critical for SIL2-compliant turbine trip applications per IEC 61508. The module installs directly into any available slot within a standard 3500/50 or 3500/52 rack and communicates seamlessly with the 3500 framework via the internal backplane, requiring no external configuration software. Its robust design, conformal coating, and compliance with industrial EMC standards make the BENTLY 135785-02A a trusted component in harsh environments including offshore platforms, combined-cycle power plants, and petrochemical refineries where reliability is non-negotiable.
Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | 135785-02A |
| Manufacturer | Bently Nevada (a Baker Hughes company) |
| Product Type | Relay Output Module for 3500 Machinery Protection System |
| Number of Relays | 4 independent Form C (SPDT) relays |
| Contact Rating | 2 A @ 30 VDC resistive; 2 A @ 250 VAC resistive |
| Fail-Safe Mode | Jumper-selectable (de-energize-on-fault) |
| Isolation | 500 VDC between contacts and system ground |
| Operating Temperature | 0°C to +65°C |
| Power Consumption | ~2.5 W (from 3500 rack backplane) |
| Mounting | Direct insertion into 3500/50 or 3500/52 chassis |
| LED Indicators | One per channel: green = relay energized |
| Certifications | CE, CSA, IEC 61010, suitable for SIL2 (in proper system context) |
Main Features and Advantages
Fail-safe operation for critical trip functions: The BENTLY 135785-02A can be configured via internal jumpers to operate in fail-safe mode, where any loss of power, communication failure, or internal fault causes all relays to revert to their de-energized (safe) state. This behavior aligns with IEC 61508 requirements for safety instrumented functions, making the BENTLY 135785-02A suitable for use in turbine overspeed or bearing temperature trip circuits that must default to “trip” upon system degradation.
Direct integration with 3500 alarm logic: Unlike generic relay modules, the BENTLY 135785-02A receives alarm states directly from the 3500 system’s internal data bus. It can be assigned to specific monitor channels (e.g., 3500/42M vibration card, channel 1, Alert level) through the 3500 Rack Configuration Software, enabling precise mapping of machinery conditions to external actions—such as initiating a compressor shutdown or activating a horn/strobe alarm.
Robust construction for industrial environments: Housed in a metal-reinforced plastic carrier with conformal-coated PCB, the BENTLY 135785-02A resists moisture, dust, and chemical exposure common in refineries and power stations. Each relay features gold-plated contacts for long life and low contact resistance, even under low-current signaling conditions typical in PLC input circuits.
Clear visual status and easy maintenance: Four front-panel LEDs provide immediate indication of relay coil status—green when energized—allowing technicians to verify alarm propagation during testing or troubleshooting without probing live terminals. The module supports hot removal in non-redundant racks, and replacement requires no reconfiguration if swapped with an identical unit.
Application Field
The BENTLY 135785-02A plays a pivotal role in machinery protection strategies across energy and heavy industry. In natural gas compression stations, it interfaces with 3500 vibration and axial position monitors to trigger emergency shutdown valves when rotor instability exceeds safe thresholds—preventing catastrophic bearing failure or seal rupture. The dry contact outputs are often hardwired to a separate safety PLC (e.g., Triconex or HIMA) or directly to motor starter coils, ensuring independence from the basic process control system.
In thermal and hydroelectric power plants, the BENTLY 135785-02A is used to generate turbine trip signals based on excessive shaft vibration, differential expansion, or thrust position. These signals feed into the plant’s master trip relay matrix, which de-energizes generator breakers and main stop valves. Because the BENTLY 135785-02A supports fail-safe operation, it satisfies regulatory requirements for automatic protective action even during control system faults.
Similarly, in large-scale petrochemical facilities, the BENTLY 135785-02A enables localized annunciation and interlocking—for example, activating area alarms when pump cavitation is detected or inhibiting startup sequences if previous trip conditions remain uncleared. Its compatibility with legacy 3500 racks ensures continued support for brownfield sites undergoing phased modernization, where full migration to newer platforms like System 1 is not yet feasible. Wherever rotating machinery demands dependable, code-compliant alarm actuation, the BENTLY 135785-02A delivers proven performance.
Related Products
BENTLY 3500/50: Standard 4-slot chassis; hosts 135785-02A and other 3500 I/O modules
BENTLY 3500/42M: 4-channel vibration monitor; commonly sources alarm signals to 135785-02A
BENTLY 3500/25: Speed/zero speed monitor; pairs with 135785-02A for overspeed trip logic
BENTLY 3500/32: 4-channel relay module (older variant); 135785-02A is its direct successor
BENTLY 3500/52: Enhanced 8-slot rack with redundant power; supports multiple 135785-02A units
BENTLY 133393-01: Ribbon cable; connects 135785-02A to terminal blocks like 135790-01
BENTLY 135790-01: Screw-terminal adapter; provides field wiring interface for 135785-02A relays
BENTLY 3500/92: Communications gateway; allows remote monitoring of 135785-02A relay states
Installation and Maintenance
Pre-installation preparation: Before inserting the BENTLY 135785-02A into a 3500 rack, confirm that the target slot is powered off if the system lacks hot-swap capability. Verify jumper settings for fail-safe vs. non-fail-safe operation based on the safety philosophy of the protected equipment. Ensure that the connected terminal block (e.g., 135790-01) uses appropriately rated wiring—typically 18–22 AWG—and that relay contact loads do not exceed 2 A. Configure alarm-to-relay assignments using Bently Nevada’s 3500 Rack Configuration Software prior to commissioning.
Maintenance recommendations: During routine checks, observe the front-panel LEDs on the BENTLY 135785-02A during simulated alarm conditions to confirm correct relay actuation. Periodically inspect terminal connections for signs of arcing or overheating, especially in high-cycle applications. If a relay fails to operate despite correct software configuration, test contact continuity with a multimeter or replace the module—electromechanical relays have finite lifespans under load. Always store spare BENTLY 135785-02A units in anti-static bags at ambient temperature to preserve internal components.
