FIELD OF INVENITON
The invention relates to a device for multi channel sensor live data cable
conduiting of blade vibration monitoring system and the method for the same.
BACKGROUND OF THE INVENTION
Blade failures in steam turbines, gas turbines and compressors need to be
avoided in the interest of safety and reduced downtime of a plant. A need is felt for
continuous monitoring of vibrations of critical stage blades. Blade Vibration Monitoring
System (BVMS) monitors vibrations of blades during actual running of turbine. Non contact
Eddy Current Probes are installed around a bladed stage of rotor to measure the time-of-
arrival of the blade during running of the turbine with reference to the speed of the
turbine. The eddy current sensors are mounted on the casing or guide blade carrier. The
signals from the sensor are collected at the DAC through signal cables/wires with proper
conduiting, routing and sealing at the turbine end so as to prevent vacuum leakage.
In earlier installations as shown in Fig 1 to bring out the sensor cables from
the turbine casing, a single channel vacuum seal is used in literature, wherein cable from
each sensor is brought out solely through a single gland and a corresponding drilled hole in
the casing of the turbine. This calls for number of holes in the casing depending on the
number of sensors installed. The number of holes drilled is always a concern of worry
owing to the disadvantages stated below:
• The amount of work involved in bringing out each cable out of the turbine is
enormous. It calls for routing of each sensor cables individually leading to more
engineering effort.

• Drilling of number of holes depending on the number of sensors is always a risk
due to in situ condition. The method calls for reliability and repeatability of the
quality of the drilled hole and the quality of weldment achieved. It is highly
impossible to provide a number of leak proof weldings at the casing outlet
considering the human effort reliability and repeatability.
• Multiple holes consume more space on the casing
• The Leak-proofness of the seal at each casing penetration is important as it
affects the performance of the turbine owing to the maintained pressure
conditions in the turbine.
• Plugging of multiple holes when a need arises is time consuming and laborious.
• A single - channel casing penetration cannot be used for penetration through
multiple surfaces
Hence, the proposed device used for multi channel sensor cable conduiting of
Blade vibration Monitoring System as shown in Fig 2 addresses the disadvantages of the
prior-art and provides an improved system and method of assembling the same.
OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose a device for multi
channel sensor live data cable conduiting of blade vibration monitoring system and the
method for the same which is capable of eliminating the disadvantages of prior art.
Another object of the invention is to propose a device for multi channel
sensor live data cable conduiting of blade vibration monitoring system and the method for

the same which is capable of ensuring leak-proofness and sealing by avoiding multiple
drilling of holes and weldments.
A further object of the invention is to propose a device for multi channel
sensor live data cable conduiting of blade vibration monitoring system and the method for
the same which is able to provide a multi-channel seal with a flexibility to use through
multiple surfaces.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 - Shows prior art casing penetration
Fig. 2 - Shows a Canister according to the invention.
Fig. 3 - Shows the Canister Flange according to the invention.
Fig. 4 - Shows the Canister plate according to the invention.
Fig. 5 - Shows the Canister in assembly condition.
Fig. 6 - Conduits routed through assembled canister.
Fig. 7 - Sectional view of Canister fixed to longitudinal girder.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
The device for multi channel sensor cable conduiting consists of a flange (1)
as shown in fig (3) and called a Canister flange and a plate called as Canister plate (2) as
shown in fig. 4. Assembly of this flange (1) and plate (2) is shown in fig. 3. The flange (1)
is made of mild steel, hardened and ground having 8 nos of Pitch circle diameter (PCD)
threaded holes of 14 mm BSW. The plate is also made of mild steel, hardened and ground.
The plate (2) has 8 numbers of PCD holes, the PCD being the same as that of Flange (1).
The plate (2) is fixed on the flange (1). The Pitch circle diameter of the threaded hole (3)
of Flange (1) and holes (4) of plate (2) is 280 mm. There are 5 nos of 27 mm Q 140 mm
PCD holes on the canister plate (2) for Conex Glands. The outer diameter of the flange (1)
having a thickness of 22 mm (5) is 340 mm (6) while that of the plate (2) is also 340 mm
(7).

As shown in fig. 6, the assembled canister (8) is connected with a pipe (11)
carrying the conduits (10).
Installation of Blade Vibration Monitoring System consists of Sensors which
are fixed in the lower half of the Diffuser casing of LP Turbine facing the blades. To protect
the live data cables from high temperature and humid conditions existing inside the LP
Turbine, they are enclosed in Soft Steel Conduits (10) and anchored to the casing. The SS
pipe (9) of diameter 60 mm and length 700 mm is fixed between the two layers of
longitudinal girder (14) which is under vacuum condition as shown in Fig 7. Conduited
cables are passed through the pipe (9) into the canister (8) welded to the casing. Canister
plate (2) holds the cables coming out of the casing. Support brackets (11) four in number
are used for additional support. The orange cables (12) will come out of the Soft Steel
conduit towards sensor side, which is in vacuum condition (13). The conduits (10) are
routed out of turbine through canister (8) and the cables coming out of the sensors are
routed through LP Longitudinal Girder (14). The girder is two layered of thickness 25 mm
and is of MS material. The two layers are separated by a distance of 700 mm and are
directly not accessible as shown in Fig 7.
In commercially available casing penetrators, only cables (without conduits)
are passed through single layer of casing penetration. Using this device casing penetration
of conduited Multi cables through two layers of casing can be done as shown in Fig 6 & 7.

WE CLAIM
1. A device for multi channel sensor live data cable conduiting of blade vibration
monitoring system and the method for the same, the said device comprising;
a flange (1);
a plate (2) for fixing on the flange (1);
a pipe (9) for carrying the conduits (10);
a plurality of support brackets (11);
characterizing in that,
the soft steel conduits are disposed in the assembly for enclosing the live data
cables for protecting them from high temperature, humid conditions existing
inside the L.P. turbine when the pipe (9) is fixed between the two layers of
longitudinal girder (14) for a guiding the conduited cables into the Canister (8)
welded to the casing wherein the canister plate is disposed for holding the
cables coming out of the casing.
2. The device as claimed in claim 1, wherein the steel pipe (9) is of 60 mm
diameter and 700 mm in length.
3. The device as claimed in claim 1, wherein four numbers of support brackets
(11) are disposed for additional support.
4. A device as claimed in claim 1, wherein the pitch circle diameter of 8 numbers
of 14 mm dia threaded holes (3) on the canister flange (1) and 8 numbers of
14 mm dia holes (4) on the canister plate is 280 mm when 5 numbers of 27
mm dia holes are disposed on a pitch circle diameter of 140 mm on the
canister plate to accommodate sealing glands.

5. The method for multichannel sensor live data cable conduiting of blade
vibration monitoring system comprising;
enclosing the live data cable in soft steel conduits to protect them from high
temperature and humid conditions existing inside the LP turbine; fixing the
soft steel (SS) pipe (9) between the two layers of longitudinal girder (14)
disposed under vacuum condition;
passing the conduited cables through the pipe (9) into the canister (8);
welding the canister to the casing;
supporting the canister with supporting brackets (11);
wherein the canister plate (2) holds the cables coming out of the casing when
the conduits are routed out of turbine through canister (8) and the cables
coming out of the sensors are routed through two layered LP longitudinal
girder (14).

ABSTRACT

A device for multi channel sensor live data cable conduiting of blade vibration
monitoring system consists of a canister flange (1) and a canister plate (2) assembled to
form a canister assembly (8) and is welded to the casing. The Canister (8) is supported by
a plurality of support brackets (11). The canister plate (2) holds the cables coming out of
the casing. The conduits (10) are routed out of turbine through canister (8).