Bently Nevada 3300/50, Руководство по эксплуатации

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Tachometer Operation
6 MONITOR FUNCTIONS
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ROTOR SPEED MONITORING - The Tachometer function provides continuous monitoring of shaft
rotative speed. The Tachometer accepts input from either a proximity probe or magnetic pickup (not
recommended). The Tachometer measures the time between Keyphasor pulses and calculates the
rotor speed in revolutions per minute (RPM). The monitor displays the rotor speed on the front panel
and provides a proportional voltage or current recorder output The Tachometer also outputs Alert
status via rear panel relay contacts for external annunciation.
ZERO SPEED - The 3300, Tachometer provides, as a factory installed option, a Zero Speed function.
Zero Speed measurements are generally taken on turbines, generators and other rotating machinery
with large rotors.
Zero Speed is a preselected shaft rotative speed that allows for proper engagement of the turning
gear. Continuous shaft rotation during machine shutdown is imperative to prevent shaft bow that
could lead to possible machine damage during startup,
The Zero Speed function requires inputs from two transducers. Voting logic between the two
transducers minimizes false Zero Speed indication in the event of a transducer failure. When the Zero
Speed function is enabled, and the preselected Zero Speed is reached, an Alert LED indicates the
condition. Alert relay contacts are also provided for use with an external indicator such as an
annunciator panel.
ROTOR ACCELERATION - The 3300 Tachometer provides, as a factory installed option, a Rotor
Acceleration indicator. The Rotor Acceleration function provides an indication of a machine's rotative
acceleration. The acceleration/deceleration information is displayed on the front panel. A recorder
output, as well as Alert relay outputs are provided.
Rotor Acceleration is used with machinery during startup or shutdown. The original machine
manufacturer's recommended ramp up or ramp down rate must be maintained to minimize possible
damage.
PROBE GAP VOLTAGE - Probe gap is measured in negative DC voltage and is directly proportional
to the gap between the face of a proximity probe and the surface being monitored. Probe gap
voltage for each transducer is displayed on the front panel by pressing the GAP switch.
TRIGGER OK - The TRIGGER OK LEDs indicate the status of the transducer input signal, and the
monitor. The TRIGGER OK LEDs remain on as long as the Tachometer is receiving valid input signals
and the monitor is OK. The LEDs will extinguish when the input is less than 1 RPM or greater than
99,999 RPM. An invalid trigger will not cause the system OK relay to go NOT OK.
OK RELAY - The OK Relay is located on the Power Input Module. Every monitor in the rack must be
OK or bypassed to energize the OK Relay.
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