VIBRATION MONITORING OF FANS INSTALLED IN ROAD TUNNELS
CEMB SPA
Via Risorgimento, 9
Mandello del Lario (Lc), Italy
stm@cemb.com
www.cemb.com
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 2x1mm2 - up to
400 metres 2x1.5mm2 - up to 800 metres 2x12.5m2 ).
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.
CEMB SPA – Mandello del Lario
1.2.4. Resistance to environmental agents.
The transducer should be tightly sealed and insensitive to ambient humidity (max.
25%) and resistance to contamination by dusts and lubricating oils with a degree of
protection IP 65 (CEI standards)
1.2.5. Cables and connectors.
The transducers are complete with male-female connection to MIL standards, able
to withstand the mechanical and thermal stresses described in points 1.2.3 and
1.2.4.
1.2.6. Mounting.
It should be possible to install the transducer in any direction and fasten it with a
sufficiently rugged screw (e.g. M8 thread).
TEST INSTRUMENTS
1.3.1. Types of instruments.
All instruments are fully transistorized and the signal coming from a transducer is
sent to the respective conditioning and measuring circuit. The scanning system is
not permissible.
1.3.2. Measurement range.
The instrument should allow measurement and supervision of the RMS value of the
vibration speed within a range from 0 to 10 mm/s.
1.3.3. Frequency range.
The instrument response is linear in a frequency range from 10 to 1000 Hz.
1.3.4. Threshold discriminator circuit.
Each measuring channel is provided with a threshold discriminator circuit of static
type with amplitude comparator, suitable for driving an output relay (SPDT contact)
and indicator lamp (LED).
The tripping level of the alarm threshold is adjustable between 10% and 100% of
the measuring scale.
The alarm threshold is provided with a time delay device, independent from the
value and adjustable from 0 to 20 seconds.
The system output logic is as follows: under normal condition (vibration level below
the threshold) the relay is de-energized and the LED is unlit. The alarm threshold is
of the “unlatched” type, i.e. the output relay remains energized and the relative LED
is lit up only as long as the input signal is higher than the threshold value.
CEMB SPA – Mandello del Lario
1.3.5. Analog output.
Each vibration channel sends an output signal 4 to 20 mA proportional to the RMS
value of the vibration speed measured.
1.3.6. Environmental conditions.
The instruments operate correctly within a temperature range from –10°C to +
50°C.
1.3.7. Power supply.
Instrument power supply is 220 Vac – 50 Hz
1.3.8. Composition of the instruments.
Each instrument is mounted in a 19” rack enclosure able to process at least 16
measuring channels. The following are installed in the unit:
- one power supply complete with main switch
- a number of signal processing boards which depend on the number of fans to be
monitored.
CEMB SPA – Mandello del Lario
POWER SUPPLY MODULE PW T1-C
FUNCTION
Power supply module PW T1-C is able to supply stabilized voltage up to 8 processing
modules T1-C. The power supply is mounted in a wall-mounted unit.
The instrument can be mounted in suitable enclosure with degree of protection IP54 for
applications in protected environment.
TECHNICAL CHARACTERISTICS
External connections : terminal board WEIDMULLER TOP 1,5 GS
Supply voltage : 100 – 220 V 50 Hz ± 10%
Max. power consumption : 50 VA
Output voltages : + 15 V - 15 V
Max. output currents : + 15 V = 1 A
- 15 V = 0.5 A
Unit : dwg. 23950
CEMB SPA – Mandello del Lario
OVERALL DIMENSIONS
4 HOLES dia. 6.5
POWER SUPPLY MODULE
PROCESSING MODULES
(up to 8 modules)
PROCESSING RACK
CEMB SPA – Mandello del Lario
PROCESSING MODULE T1-C
FUNCTION
The T1-C processing module is able to process the signals coming from two vibration
transducers type T1-40 and to supply, for each signal, an analog output and an alarm
contact. The module can supply the analog outputs proportional to the axial position or
speed of vibration.
Such module is extremely compact in design while it allows simple and modular monitoring
of the vibrations.
CEMB SPA – Mandello del Lario
TECHNICAL CHARACTERISTICS
External connections : terminal board WEIDMULLER TOP 1,5 GS
Supply voltage : + 15 V / - 15 V
Max. current drawn : + 15 V = 120 A
- 15 V = 16 A:
N° of channels processed : 2
Unit of measurement of vibration : 0 to 100 µm, 0 to 300 µm
0 to 10 mm/sec 0 to 30 mm/sec
Output signals (terminals
OUT1 and OUT2) : 4 TO 20 mA proportional to the input vibration
Alarm contacts (terminals
ALARM 1 – ALARM 2) : 1 SPDT for each channel
Max. current, alarm contacts : 3A
Max. voltage, alarm contacts : 250 V
Alarm adjustment : 0 to 100% of the measurement range
Alarm delay time : from 0 to 20 seconds (approx.)
Alarm condition indicator : Red LED located close to the alarm level
setting potentiometer
CEMB SPA – Mandello del Lario
CEMB SPA – Mandello del Lario
ASTA07120
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