Alignment Drawing Graph 11 , 12

Alignment Drawing graph 10

Alignment Drawing Graph 9

Alignment Drawing Graph 8

Alignment Drawing Graph 7

Alignment Drawing Graph 6

Alignment Drawing Graph 5

Alignment Drawing Graph 4

Alignment Drawing Graph3 Thraw circle TGB

Alignment Drawing Graph 2 Throw Circle

Alignment Drawing Graph 1

LEVELLING ALIGNMENT AND CENTERING OF VERTICAL MACHINE

LEVELLING ALIGNMENT AND CENTERING OF VERTICAL MACHINE
	CONTENTS
1.	INTRODUCTION
2.	STARTING CHECKS
3.	SETTING OF THRUST BEARING ELEVATION
4.	LEVELLING OF THRUST BEARING
5.	ALIGNMENT OF ROTOR
6.	COMBINED ROTATIONAL CHECKS ON GENERATOR AND TURBINE SHAFTS.
7.	FORMATE FOR ALIGNMENT READING
8.	MAGNETIC CENTERING
9.	ANALYSIS OF ALIGNMENT READING
9.1.	ANALYSIS OF ALIGNMENT READING BY THROW CIRCLE METHOD
9.2.	ANALYSIS OF ALIGNMENT READING BY VECTOR METHOD
9.3.	ANALYSIS OF ALIGNMENT READING BY TRIGONOMETRIC METHOD

LEVELLING , ALIGNMENT AND CENTERING OF SUSPENDED TYPE VERTICAL MACHINE

LEVELLING , ALIGNMENT AND CENTERING OF SUSPENDED TYPE VERTICAL MACHINE
1. INTRODUCTION:
	Levelling and alignment along with centralising are most important in the erection of hydro generator. Trouble free operation of the machine depends on satifactory achievement of level alignment and centralising of the rotor. These operations must ensure that : -
1.1	Thrust bearing is level to the optimum level
1.2	Thrust bearing or Upper bracket elevation is set to give corect turbine runner, elevation during normal opration.
1.3	The axis of Turbine and Generator shaft are in one vertical line
1.4	The Turbine runner centre and Generator rotor center concide with centre lines of stay ring and stator core respectively
	For the process with respect to levelling , alignment and centralising following general sequence can be followed:
2. STARTING CHECKS:
2.1.	The turbnine shaft will have to be set truly vertical and central to the stay ring by the turbine erector. The turbine shaft however , will be set lower than its normal running position to clear the coupling spigot when generaor shaft is lowered . The generator erector has to satisfy him self that coupling spigot doesnot foul with Generator shaft when lowered.In case of (Vertcal pelton turbine) Turbine shaft was lowered on Nozzel alignment disc till coupling of the turbine shaft with Generator shaft.
2.2.	Dialing location and coupling face of UGB , LGB , TGB journel surface , turbine & generator to be cleaned and polished with out most care.It is to be noted that turbine shaft and generator shaft coupling face cleaned and polished before lowering of rotor. In case of Tala machine in some cases dial gauge reading were also taken in Top shaft and spider coupling and bottom shaft and spider coupling to check generator shafts train aligned with its own axis.
2.3.	The Thrust collar circumference to be divided to eight equi-distance circumferential points for the purpose of level and alignment reading. The equi-distance points location to be vertically transferred to all dialing location and outmost care to be taken for the purpose.
2.4.	Arrangement to be made for positioning of dial gauge for measurement purpose and correct seating position for taking reading.
2.5.	All dial gauges (at least 10 numbers) are to be checked for physical healthyness and for the correctness of reading.
2.6.	For checking of level block level or spirit level with 1 in 50000 accuracy can be used.
2.7.	For taking level reading block level to be placed on thrust collar surface and to be set to zero.
3. SETTING OF THRUST BEARING ELEVATION:
3.1	Checks the soleplates and bracket holding down bolts are tightened.
3.2	The bracket elevation can be set by adjusting the shims and it is to be ensured that the turbine runner will be at the desired level under running conditins.
3.3.	Allowance must be made for deflectionof the bracket and thrust bearing spring under normal load (I.e. weight of rotating parts and hydraulic thrust)
	a). Bracket deflection at normal load Expected Deflection : a
	b). Bracket deflection with Rotor and shaft load alone Expected Deflection : b
	c). Spring deflection at normal load Expected Deflection : c
	d). Spring deflection with Rotor and shaft weight alone Expected Deflection : d
3.4.	Turbine erector will advice the amount (T) by which the turbine coupling is below the normal running position. The Generator must then be set at a height above the turbine coupling by the amount equal to T plus additional deflectionof the thrust bearing at full load . This is equal to ( T + (a + c)- (b+d)) mm
3.5	It is essential that any adjustment of the bearing bracket shims made to obtain the correct coupling gap must precisely the same (by micrometer measurement) at each bracket feet , other wise the bracket will be thrown out of level.
4. LEVELLING OF THRUST BEARING :
4.1	The generator Rotor is supported at the thrust bearing but not coupled to the turbine shaft.
4.2	Fit four of the guide bearing pads of generator guide bearing which is nearer to the thrust bearing with alignment pivot at 45º intervals. Close up the clearance to a minimum with pad locking bar ,yet allowance to the Rotor to Rotate. Guide bearing pads are to be applied with Servo prime 46 lubricant.
4.3.	Place precision level ( 0.02 mm in per division per meter or 1 in 50000 accuracy ) on the top face of the thrust collar in any position. Set the level so that the bubble is exactly at the centre.
NOTE:	1) Level must be checked for zero error.
	2). The level must be firmly secured to avoid jerks while rotation is being given
4.4.	The Rotor is rotated thruogh 45º and the level gauge reading is noted.The same procedure is repeated for 90º , 135º , 180º , 225º , 270º , 315º and 360º rotation.
NOTE :	Before starting rotation HS system to be put on and after rotating 45º HS system to be put off. After each rotation through 45º and putting off of HS system wait time of around 120 seconds to be allowed to elapsed before taking reading to get more accurate reading.
4.5.	For a truly horizontal thrust face , the reading of the precision level would be constant. It is not expected that it will be practicable to achieve precisely the same level reading in all directions of the shaft and the results can be taken as satisfactory if the maximum reading is within 1 division of the level with a level accuracy of 1 in 50000.
4.6.	To obtain the required level accuracy , the shims under thrust bearing bracket feet are adjusted. Minimum number of the shims for a given adjustment should be used i.e. thicker shims are to be used whereever possible.
4.7.	After correction of level or after achieving required level accuracy rotor alignment process to be started.
5. ALIGNMENT OF ROTOR
5.1.	Set up two dial gauges each on the guide bearing journel surface nearest to Thrust bearing and at the Generator coupling in two mutually perpendicular directions X and Y (Down Stream). The mean value of the readings in X and Y axis is then used.
5.2.	Rotate the rotor through 45º , 90º , 135º , 180º , 225º, 270º , 315º and 360º. Record readings of the dial gauges in the foramte given below as per process as described as above:
5.3.	The accuracy of alignment is computed from the following table :
	X_AXIS
	LEVEL 2 3 4 5 6 7 8 1 2
	ANGLE OF ROTOR 0º 45º 90º 135º 180º 225º 270º 315º 360º
	GEN. COUPLING (a)
	GEN. UPPER GUIDE BRG. (b)
	GEN. LOWER GUIDE BRG. ©
	d=c-b
	e=a-b
	Y_AXIS
	LEVEL 8 1 2 3 4 5 6 7 8
	ANGLE OF ROTOR 0º 45º 90º 135º 180º 225º 270º 315º 360º
	GEN. COUPLING (a)
	GEN. UPPER GUIDE BRG. (b)
	GEN. LOWER GUIDE BRG. ©
	d=c-b
	e=a-b
NOTE:	The reading at 0º and 360º should be same within the tolerance of reading accuracy (minimum permissible closing error). If these reading consistently show difference , there is possibility that the shaft is not freely rotating. The oil retaining sleeve or some such other component may be touching the rotor. This has to be checked.It is to be checked wheather any jerk is produced while rotating the rotor which affects the initial reading. If so , reason for jerk to be evaluated and necessary correction applied or the initial reading should be taken after the jerk.
5.4.	After applying necessary correction to keep the throw at Generator lower guide bearing and Generator coupling flange to a desired level as per standard , Turbine and Generator shaft to be coupled for further combined alignment checking.
6. COMBINED ROTATIONAL CHECKS ON GENERATOR AND TURBINE SHAFTS.
6.1.	Pull the turbine shaft towards the generator shaft and couple the flanges by permanent bolts. The force of tightening the bolts should be identical.The diametrically opposite bolts should be tightened first.Technical requirement related to shaft tightening arrangement to be followed.
6.2.	Remove the turbine guide pads and the seals and the turbine support so that the shaft is suspended freely from the thust bearing.
6.3.	The gap between the turbine runner and stay ring should agree with the setting obtained by the turbine erector while centralising the shaft. The generator guide bearing are to be adjusted if necessary. If the centralising affects the bracket centering by more than 0.25 mm , the bracket will also have to be centralised , which is as followed normally.
6.4.	Fit the gauges on the turbine guide bearing journel level in X and Y Axis.
6.5.	Rotate the rotor through 45º , 90º ,135º , 180º , 225º , 270º , 315º and 360º. The dial gauge reading are recorded in the format given below in clause 6.7 . For taking reading process as described above to be followed.
6.6. FORMATE FOR ALIGNMENT READING
6.6.1.	Format for suspended type generator
	X_AXIS
	LEVEL 2 3 4 5 6 7 8 1 2
	ANGLE OF ROTOR 0º 45º 90º 135º 180º 225º 270º 315º 360º
	TURBINE G B (a)
	GEN. UPPER GUIDE BRG.(b)
	GEN. LOWER GUIDE BRG.(c)
	d=c-b
	e=a-b
	Y_AXIS
	LEVEL 8 1 2 3 4 5 6 7 8
	ANGLE OF ROTOR 0º 45º 90º 135º 180º 225º 270º 315º 360º
	TURBINE G B (a)
	GEN. UPPER GUIDE BRG.(b)
	GEN. LOWER GUIDE BRG.(c)
	d=c-b
	e=a-b
NOTE:	The note in para 5.3 will also apply here.
6.7.	As per NEMA standards the maximum throw circle diameter permitted at the turbine guide bearing is determined by formula :-
	0.05 L / D in mm
	Where L is the distance between the generator thrust face and turbine guide bearing, D is the out side diameter of the thrust bearing. If by this standard the permissible throw the turbine guide bearing clearance, the throw should be limited to a value of a little below the turbine guide bearing radial clearances.
6.8.	The throw at the bearing journals and flange is corrected if it exceeds the permissible limit defined above. Small throw may be corrected by differential tightening of the corresponding bolts of flange connections. If the throw is considerably large , aligning of shaft train can be done scrapping of end surface of turbine or generator shaft or by shimming of stainless steel packing placed between flanges of Turbine and Generator shaft coupling. Packing should be graded with steps covering not less than 1/4th radial depth of flange.
6.9.	After applying necessary correction to keep the throw at Generator lower guide bearing and Turbine guide bearing to a desired level as per standard. It may be necessary to change 'e' and 'd' togerther. In such cases , shims have to be put or scraping may have to be done at the surface between thrust collar and runner disc..Onec throw has been brought to the acceptable limits , final level , alignment and centering reading to be taken and if necessary throw reading at collector assembly may noted (this requirement decided by Generator erector).The process for throw checking in collector assemby as follows and for details analysis same process may be adopted as for Generator.
6.10.	The collector is now assembled.
6.11.	Fit two dial gauges each at one of the collector rings and at generator guide bearing nearer to thrust bearing. Rotate the rotor 45º , 90º ,135º , 180º ,225º , 270º , 315º and 360º. The dial gauge readings are recoded in the format given below.
	X_AXIS
	LEVEL 2 3 4 5 6 7 8 1 2
	ANGLE OF ROTOR 0º 45º 90º 135º 180º 225º 270º 315º 360º
	COLLECTOR RING (a)
	GEN. GUIDE BRG. (b)
	c=a-b
	Y_AXIS
	LEVEL 8 1 2 3 4 5 6 7 8
	ANGLE OF ROTOR 0º 45º 90º 135º 180º 225º 270º 315º 360º
	COLLECTOR RING (a)
	GEN. GUIDE BRG. (b)
	c=a-b
6.12.	The throw circle diameter as defined earlier should be limited to NEMA standars or 0.2 mm , whichever is lower.
6.13.	The guide bearing pads of both the turbine and generator are fixed with the clearance stated in the appropriate drawings.
6.14.	The Generator stator is centralised with respect to the rotor.
6.15.	The air agp length is measured both at the top and bottom of the poles. Minimum gap at the pole centre is to be recorded. The air gap measurement has to be taken at every pole.
6.16.	The Rotor is now rotated and the air gap at one pole is recorded rotating the pole through 45º , 90º ,135º ,180º ,225º , 270º , 315º and 360º position to get Rotor form with respect to fixed point in Stator (D/S mark in Stator) and Stator form with respect to particular pole of Rotor (usually pole no. 1).
6.17.	The maximum variation of air gap length should be limited to ± 5 % of the normal value but a variation of 10 % can be allowed at a few places.
7. MAGNETIC CENTERING
	For magnetic centering the centre line of the rotor and stator shall be at the same elevation during operation. To achieve this following precaution are to be taken during erection.
7.1.	During mounting of pole on rim assembly the centre line of every pole is kept at the same elevation. To acheievd this the pole stope height can be modified to suit on assembly.
7.2.	As mentioned in clause 3.4 the Generator is set at higher elevation. Therefore . At stand still condition the centre line of rotor shall be at higher / lower elevation than stator centreline by the same amount as prescribed in the relevant drawing. To achieve this shims shall be added or removed from the bottom of stator sole plates.
NOTE :	The Levelling , Alignment and centering process described as above to be applicable to suspended type vertical machine .The same methodology for the application of levelling , centering and alignment of semi - umbrella & umbrella type vertical machine can be adopted.But for calulation purpose values of 'd' and 'e' to be considered based on the bearing location for those type of machine.

ANALYSIS OF ALIGNMENT READING BY THROW CIRCLE METHODS

ANALYSIS OF ALIGNMENT READING BY THROW CIRCLE METHODS
1. To analysis alignment reading one will need the following items.
1.1. One good graph paper to plot the displacement recorded in the X & Y direction.
1.2. One Good geometry box with pencil, eraser, pencil sharpener, scale, compass, divider, protractor and set squares etc.
2. Now in the graph paper plot co-ordinate axis amd mark XX' and YY' axis.
3. To find out the throw plot the dispalcement of (x, y) on a graph paper to a suitable scale. For example plots points (0,0) ; (1,-3.5); (0,-1) ; (0.5 , -1) ; (1.5 ,0) ; (1.5,-6.5) ; (-1.5 ,-3) ; (-6.5,-2) & (-3.5,0) LGB reading of combined alignmnet checking.
4. Out of the total eight co-ordinate points three co-ordinate points have to choose in such a way that when a circle is drawn with minimum radius will pass through these three points and also includes all other points within the circle.
4.1. To draw the circle first draw a triangle with the selected three points. Then draw bisector of all the side. The cross section of all bisector will be the centre of the circle. Now taking the cross-section points as the centre and any other points as radius circle can be drawn.Diameter of such a circle should be in close agreement with the throw (run out ) reading obtain in factory. The throw will be half of the throw circle diameter. The throw circle should not exceed 0.1 mm. The angle of throw can obtained by drawing a line connecting centre of co-ordinate axis and and centre of the circle.
5. The throw at lower guide bearing and the turbine guide bearing journal to be calculated independently and necessary correction measure to be taken independently.

ANALYSIS OF ALIGNMENT READING BY VECTORS RESULTANT METHODS

ANALYSIS OF ALIGNMENT READING BY VECTORS RESULTANT METHODS
1. To analysis alignment reading one will need the following items.
1.1. One good graph paper to plot the displacement recorded in the X & Y direction.
1.2. One Good geometry box with pencil, eraser, pencil sharpener , scale, compass, divider, protractor & set squares, etc..
2. Now in the graph paper plot co-ordinate axis and mark XX' and YY' axis.
3. To find vectors resultant the opposite vectors are transferred to opposite direction. For example vector 5 shifted to vector 1 side (1-5) , vector 6 shifted to vector 2 side (2-6) , vector 7 shifted to vector 3 side (3-7) and vector 8 shifted to vector 4 side(4-6).
4. To find out the throw plot the vector group resultant ( 1-5) & ( 3-7) ; (3-6) & (4-8) valus of ( x,y ) on a graph paper to a suitable scale. For example plots points (3,-0.5) ; (1,7) ; (2 ,1.5) and (0,1.5) for LGB ; (0,2.5) ; (3.5 , 2.5) ; (2.5 , -0.5) & (1.5 ,-2.5) for TGB of combined alignmnet checking.
5. With vector group of (1-5) and (3-7) one parallelogram is drawn and also its resultant of R-13 . With vector group (3-6) and (4-8) parallelogram is drawn and also its resultant R-28.Finally with the resultant R-13 and R-28 total resultant parallelogram is drawn and its resultant ploted to find net total resultant.
5.1. From the ploted graph value of net resultant can be calculated as per the scale of the graph. The average value of the net resultant will be the throw and the throw direction will be opposite to the direction of force. The throw angle can be measured from the ploted graph .
6. The throw at lower guide bearing and the turbine guide bearing journel to be calculated and necessary correction measure to be taken independently.