Bently Nevada 3500/50M tachometer module

Bently Nevada 3500/50M tachometer module

The Approximately Nevada 3500/50M tachometer module is a dual channel module designed specifically for mechanical equipment condition monitoring. It can receive signals from proximity probes or magneto electric sensors, enabling real-time monitoring of shaft speed, rotor acceleration, and rotation direction. It triggers alarms through programmable alarm thresholds and is widely used in rotating machinery such as industrial turbines, generators, and compressors. It also supports providing conditioned Keyphasor signals to the 3500 rack backplane without the need for additional Keyphasor modules.

Core functions and positioning

1. Core monitoring capability

The module supports four types of monitoring configuration schemes, which can be flexibly selected according to the scenario, covering key parameters such as speed, acceleration, and direction:

Configuration plan, monitoring parameters, applicable scenarios

Option 1: Speed monitoring, threshold alarm, and speed bandwidth alarm for devices that need to monitor the range of speed fluctuations (such as generators)

Scenario 2: Speed monitoring, threshold alarm, and zero speed notification require determining the start/stop status of the equipment (such as compressor start/stop confirmation)

Plan 3: Equipment for speed monitoring, threshold alarm, and rotor acceleration alarm to prevent sudden increase/decrease in speed (such as turbine overspeed acceleration prevention)

Option 4: Speed monitoring, threshold alarm, and reverse rotation notification for devices that prohibit reverse rotation (such as pump type mechanical anti reverse protection)

2. Featured Features

Keyphasor signal sharing: It can be configured to output conditioned Keyphasor signals to the 3500 rack backplane for use by other monitoring modules (such as vibration monitoring modules), reducing the number of modules in the rack.

Peak holding: Automatically stores the highest forward speed, highest reverse speed, and number of reversals during device operation. The peak can be manually reset for easy fault tracing.

Flexible alarm configuration: Supports two-level alarms (Alarm 1/Alarm 2), and the alarm threshold and delay time can be set by software to avoid false alarms (such as short-term speed fluctuations not triggering alarms).

Technical parameters

1. Input parameters

The module is compatible with two types of sensors, and attention should be paid to the usage restrictions of magneto electric sensors (see "Safety Warning"):

Parameters, specifications, and notes

The input signal source is close to the probe (recommended), and the magneto electric sensor does not support reverse monitoring or zero speed monitoring (the signal edge is unclear at low speeds, making it easy to misjudge)

The input signal range is+10.0V~-24.0V. If the signal exceeds the range, it is limited internally by the module to avoid damage

Input impedance standard: 20k Ω; TMR (Triple Modular Redundancy): 40k Ω; Built in isolation barrier: 7.15k Ω, suitable for different system requirements with different configurations

Minimum input frequency close to the probe: 0.0167Hz (1rpm, 1 pulse/rev); Magnetic electric sensor: 3.3Hz magnetic electric sensor does not support low-speed monitoring

The maximum input frequency of 20kHz corresponds to a maximum speed of 99999rpm (matching the number of pulses per revolution)

Number of pulses per revolution, rotor acceleration/zero speed channel: 1-255 pulses per revolution; Other channels: 0.0039~255 pulses per revolution, suitable for speed measuring gears with different numbers of teeth

2. Output parameters

Covering status indication, signal buffering, recording output, etc., to meet monitoring and data recording requirements:

Output type, specification, and function

Front panel LED OK (normal operation), TX/RX (rack communication), Bypass (bypass mode) intuitively judge the working status of the module

Buffer sensor output with 1 coaxial connector per channel (short circuit, ESD protection) for sensor signal multiplexing (such as simultaneous access to oscilloscope debugging)

The sensor power supply is 24VDC, with a maximum of 40mA per channel to provide power for the proximity probe

The recorder outputs a current signal proportional to the full range, with a resolution of 0.3662 µ A/bit, used for data recording and trend chart drawing. Short circuits do not affect module operation

Current output voltage range 0~+12VDC, load resistance 0~600 Ω, suitable for most industrial recorders

Output update rate of approximately 100ms to ensure real-time performance while avoiding data redundancy

3. Accuracy and alarm parameters

Parameters and specifications

Speed accuracy<100rpm: ± 0.1rpm; 100~10,000rpm：±1rpm； 10000~999999rpm: ± 0.01% true speed

Acceleration accuracy ± 20rpm/min

Alarm threshold range 0~100% full scale (software adjustable)

Alarm delay Alarm 1:1~60 seconds (1-second step); Alarm 2:1~60 seconds (0.1 second step size)

Alarm hysteresis 0.2~2.5V (user selectable to prevent frequent switching of alarms)

4. Physical and power consumption parameters

Module type, size (height x width x depth), weight, rack occupancy