CEMB USA TMP - Manual (Page 2)

CEMB SPA – Mandello del Lario
INSTRUMENT FOR MONITORING VIBRATIONS OF FANS INSTALLED IN ROAD
TUNNELS
PURPOSE OF THE INSTRUMENT
The instrument measures and monitors the vibrations of each fan installed. It allows
checking for correct machine operation over a period of time thus preventing catastrophic
failures.
Hence it is possible to stop the fan when the vibrations exceed a preset value and to
schedule maintenance work in order to replace damage parts as well as to clean the
blades (uneven deposits would generate unbalances and therefore vibrations) or to check
the fan fastenings, etc.
1. TECHNICAL DESCRIPTION OF THE SYSTEM
1.1. GENERAL
A seismic vibration transducer is installed on the housing for each fan according to
any radial direction at random.
The signal generated by the transducer is sent to an electronic processing unit.
Connection is via a suitably sized shielded cable (up to 200 metres 2x1mm
2
- up to
400 metres 2x1.5mm
2
- up to 800 metres 2x12.5m
2
).
The processing unit is normally installed in the centre of gravity position with
respect to the tunnel section where the monitored fans are installed.
1.2. VIBRATION TRADUCERS
1.2.1. Type of transducer.
The transducer is of the electrodynamic seismic type (velocity transducer), i.e.
designed for measuring the speed of vibration parameters; there are no amplifying
or signal linearizing circuits incorporated in the transducer).
1.2.2. Frequency range.
Frequency response of the transducer is linear in the range from 10 to 1000 Hz .
1.2.3. Temperature limits.
The transducers should be able to operate correctly in the temperature range from
– 10°C to + 100°C.