The 3500/53M is the electronic overspeed detection module of the Bently Nevada 3500 Machinery Protection System, specifically designed for reliable overspeed protection of critical rotating machinery. The module complies with API 670 / API 612 requirements, supports redundant voting architectures, delivers fast fault response, and is suitable for operation in hazardous industrial environments.

Core Positioning and Key Characteristics

Speed Monitoring Function
Each 3500/53M module provides single-channel speed monitoring, accepting one input signal from either a magneto-electric speed sensor or an eddy current speed sensor.

Supported pulses per revolution: 1 to 255 PPR

Maximum input speed: 99,999 rpm

Maximum input frequency: 20 kHz

Minimum detectable frequency: 0.0167 Hz (1 rpm)

Redundant Voting Architecture
The module supports 2-out-of-2 (2oo2) and 2-out-of-3 (2oo3, recommended) voting configurations. When combined with the 3500 redundant power supply, the system significantly improves availability and protection reliability, meeting critical safety system requirements.

Protection Logic
Provides dual-level overspeed protection, including overspeed alarm and overspeed shutdown. Overspeed thresholds and time delays are fully configurable. Supports manual or automatic reset modes and includes sensor failure detection, channel self-diagnostics, and fault alarm indication.

Outputs and Communication
Equipped with dry-contact relay outputs for alarm and shutdown functions, suitable for direct interface with the unit Emergency Shutdown System (ESD). Supports Modbus, PROFIBUS, and 4–20 mA analog outputs, enabling seamless integration with DCS and PLC systems.

Bently Nevada 3500/53M｜Overspeed Detection Module｜