Channel Configuration
Two independent speed input channels, supporting 1–255 pulses per revolution, compatible with 3300 XL eddy current and 7200 series magnetic pickup sensors.

Measurement Range and Frequency Response

Speed range: 1 to 99,999 rpm

Maximum input frequency: 20 kHz

Minimum detectable frequency:

Eddy current sensor: 0.0167 Hz (1 rpm)

Magnetic pickup sensor: 3.3 Hz

Measurement Accuracy

＜ 100 rpm: ±0.1 rpm

100 to 10,000 rpm: ±1 rpm

10,000 to 99,999 rpm: ±0.01% FS

Provides high-confidence accuracy for overspeed determination and protection logic.

Input Signal Characteristics

Signal range: +10 V to −24 V

Input impedance: 20 kΩ

Shielded cabling with single-ended grounding for enhanced noise immunity and anti-interference performance

Output Interfaces

Analog output: 4–20 mA per channel

Buffered sensor outputs

Two independent alarm relay outputs, compatible with PLC/DCS systems, enabling fast protection and shutdown response

Power Supply
Powered from the 3500 frame backplane, operating at 18–30 VDC. Typical power consumption is 8 W. Redundant power supply architecture improves overall system reliability and availability.

Overspeed Protection
Provides real-time speed monitoring with continuous comparison to programmable thresholds. Alarms and protection actions are triggered immediately when overspeed conditions are detected, preventing equipment damage.

Redundant Voting Logic
Supports 2oo2 and 2oo3 (recommended) voting configurations using multiple modules, reducing the risk of false trips and enhancing system safety integrity.

Multi-Sensor Compatibility
Supports both eddy current proximity probes (e.g., 3300 XL) and magnetic pickup sensors, enabling flexible adaptation to various rotating machinery speed measurement applications.

Programmable Alarm Functions
Supports multi-level alarm setpoints with relay outputs, ensuring rapid and deterministic protection response.

Bently Nevada 3500/53 133388-01｜Overspeed Detection I/O Module｜