Best Tutorial On Generator Alignment Procedures

Generator alignment procedures

Introduction;-In this post on Generator alignment procedures, we will discuss the Type of Misalignments, symptoms of misalignments, results of misalignments, and methods of alignment checks. I hope the tutorial will be useful to the readers.

What is alignment

The shaft is the elemental part of the design of the machine when a machine is coupled to another machine for the transmission of drive from driver to driven machine experiences the shaft alignment.

An adjustment of positioning driver (Prime mover) and driven machine (Alternator) in a straight line or parallel to each other in axial and radial directions is the definition alignment.

The improper alignment of misalignment leads to the following abnormalities and catastrophic failures.

Type of Misalignment

Types of Misalignment

Parallel Misalignment

Angular Misalignment

Results of Misalignment

1. Failure of Crankshaft and bearings.
2. Vibrations in Machine
3. The catastrophic breakdown of Components due to stress loading

Primary Symptoms of Misalignment

1. Increased Vibration

2. High body casting temperature

3. Frequent loosening/breaking of foundation bolts

4. Shims and dowels are getting loosened up.

5. Excessive leakage at seals

6. High rate of coupling failure

7. Overheating of bearings, Premature & frequent failure of Bearings

8. Overheating of components with the unusual smell of burning.

9. Unbalanced loads

10. Heavy vibrations

The misalignment attributes to the higher percentage of share in machine damage. It is essential to pay attention to the correction of alignment to curtail the operating budgets.

Reasons for performing a shaft Alignment

Reason of Misalignment

Listed below are the reasons for Misalignment

1. Whenever there is the removal of a driver or driven equipment for repairs.

2. Excessive vibration in equipment

3. Relative movement of components due to the thermal expansions.

4. Induced strain by System pipelines and electrical cables

5. Initial start-up causes the torsional movements.

6. Deformation of foundation or equipment bedplate.

7. Miscalculation of measured alignment readings

8. Wrong machining of coupling bores.

We should understand the basic knowledge of the type of alignments before proceeding further about the methods/procedures of alignment.

Methods of Alignment

The following three methods for the alignment are popularly in practice by maintenance engineers.

1. Visual Inspection method ( By straight edge)

2. DTI( Dial Indicator ) method Alignment

3. Laser Beam alignment method

Visual Method;- This Method of alignment is the rough alignment method. But it is quick and comparatively easy to carry out. But this method is highly inaccurate.

DTI (Dial Indicator) method Alignment

This method is one of the best traditional alignment methods. Aayhis Method will provide highly accurate readings than the visual straight edge method. The skill should be of high level To use this DTI technique correctly.

Laser Beam Shaft alignment technology

Importance of laser beam shaft alignment technology

Laser shaft alignment is the essential tool for the easy detection of machine conditions for the early warning of a catastrophic machine failure.

Reasons for the use of laser shaft alignment

1. Early detection of a problem in the machine to enable a proactive maintenance schedule.
2. Will control the spares consumption budget.
3. Enhancing the machine life cycle by the reduction in machine vibrations.
4. Reduced unplanned maintenance downtime.
5. It is possible to achieve the alignment measurement up to 0.00254 mm without error.
6. Enhancement of energy efficiency.
7. Laser shaft alignment technology fulfills the ISO 9001 compliance.

Comparison between Laser beam alignment and traditional alignment technology

Sr.No.Laser beam alignment TechnologyTraditional alignment technology1Faster and easier to useIt takes time to adjustments and is complicated to use.2Auto compensation of Thermal growth. Indicates the accurate alignmentComplicated calculations with the need of an experienced person for the calculations3Setting up is done in friction of time with reliable resultsResults are not reliable due to the saggy and disturbed movement during the rotation of the shaft4Record or measured reading is by instrumentsThe complicated manual calculation is not reliable5Laser beam results will not change person to personMeasurement readings will change person to person.

Alignment tools and Instruments

Traditional alignment tools (Generator alignment procedures)

1. Dial gauges with magnetic stand
2. Feeler \ Thickness gauges
3. Micrometers and Vernier calipers
4. Thermometers

Laser Beam Alignment tools

1. Measuring unit
2. Display Unit
3. Shaft brackets with chains
4. Chain tightening rod
5. Threaded extension rod
6. Country adapters for power supply
7. Micro USB cables
8. Measuring tape

Important points to follow during alignment (Generator alignment procedures)

Maintaining the same reference points throughout the procedure is the crucial part of carrying out the Alignment.

The Alignment will not be perfect if there is a change in reference points.

Component of the alignment process (Generator alignment procedures)

1. Movable Component: — is the Component that will be move during the alignment process. Generally, the Alternator is the movable Component since the Prime mover is not easy to move since it connects with all the Air, Fuel, Lube Oil, Water, and Exhaust system.
2. Fixed Component: — Prime Mover will be the Fixed Component. Shaft becomes the reference point, and prime mover remains a fixed Component.

Pre-Alignment checks

1. Rough alignment
2. Shaft run out
3. Soft foot
4. Distance between shaft ends
5. Piping strains
6. The tightening sequence of foundation bolts.

Coupling Arrangements (Generator alignment procedures)

Coupling is the link between the Prime mover and Alternator for achieving the transmission. The composition of the Alternator and prime mover is the deciding factor of the coupling design. A coupling design should support the torque transmission compatibility and reduction in torsional vibration.

Alternator design and transmission coupling depend upon the Alternator design concerning rotor support on bearings.

Alter designs are of the following two types.

1. Double bearing Design
2. Single bearing Design

Double bearing Design Alternator

In this type of design, the Alternator supports the rotor both at the Drive end and free end.

An alternator with high-level vibrations uses the two-bearing support design. Transmission of drive between prime mover shaft and alter shaft is through flexible coupling with rubber pads.

Single bearing Design Alternator

In this design, the single Alternator bearing at the no drive end supports the Alternator rotor. The coupling of the Alternator shaft and Prime mover shaft is directly through the flexible disc. This type of arrangement is torsionally rigid but has axial flexibility.

Single bearing Alternator Alignment (Generator alignment procedures)

Carry out the following procedure for the alignment of a single bearing type alternator.

1. Tighten the coupling bolts in sequence with proper specified torque.
2. Roughly check the air gap between the Rotor and Stator of the Alternator to ensure the rotor pole is not fouling with the stator winding. To carry out this procedure, use the pass the light from one end and look from the opposite end.
3. Put the Web deflection dial gauge at the no.1 web of the crankshaft. Rotate the engine manually and bring the Crankpin of the no.1 web to as close to BDC. The gauge should not touch or foul with the connecting rod.
4. Set the needle to zero.
5. Turn the engine slowly in a clockwise direction to the starboard side.
6. Register the reading
7. Again turn the crankshaft to the TDC position of the cylinder.
8. Register the readings
9. Rotate the crankshaft to Portside and register the reading
10. Rotate the crankshaft to 20 deg before the BDC of the Crankpin of the cylinder.
11. Register the reading.
12. Carry out the calculations as per the following

1. Plus difference in top and bottom reading indicates to lower the Alternator from the rear end
2. The minus reading indicates the raising of the Alternator from the rear end.
3. Side reading difference will indicate the shafting of Alternator from one side to another side axially.
4. After carrying out the alignment, take one more set of readings.
5. Enter the final readings in records of maintenance.
6. Check the alternator air gap, and the air gap should be uniform all over the circumference.
7. Check the distance at both ends of the bearings. Carry out the adjustment by shifting the stator on either side.

Double Bearing rigid coupling Alignment (Generator alignment procedures)

Step-1

1. Place the Alternator on the adjusting screws at the base frame. Maintain a distance of approximately 60 mm.
2. Adjust the distance from the base frame to the rotor center until the spigot on the alternator flange fits into the flywheel recess.
3. Tighten the coupling bolts between at the specified torque.
4. Adjust the axial position of the rotor in the alternator housing and center it as per the dimensions punched on the casing.
5. Mount the dial gauge on the drive end bearing housing and check the concentricity of the rotor within the tolerance of +/- 0.15mm.

Step 2

1. Make the front bearing accessible.
2. Loosen the adjusting screws at the front feet and allow the front end of the alternator housing to rest on the rotor shaft.
3. Raise the front end of the Alternator by adjusting screws to provide the uniform clearance 0f 0.14 mm on each side of the axle. This clearance will center the shaft in the bearing till it has a clearance of 0.28 mm.
4. Place the dial gauges on all the Alternator feet to know the distance between the alternator feet and the base frame at all corners.
5. Raise the back end of the Alternator till the achievement of -0.13 mm reding at the top and bottom of the last crank web.
6. Check the alignment at the sides also and keep it equal.
7. Check the clearance between the shaft and the front end bearing by top and bottom out log.
8. Carry out step 2 again if the front shaft is touching the bearing.

Step-3

At the accomplishing alignment, raise the front bearing by the adjustment screws till the outlog on the last crank web is 0.00 to +/- 0.01 mm.

Step-4

1. Carry out the adjustment of the chokes below the alternator feet and above and on top until surface contact establishes.
2. Tighten the bolts at the feet of the Alternator to the specified torque.
3. Carry out the final auto log on the lat crank web and maintain the dimension of 0.00 to +/- 0.02mm.

Laser Beam Alignment procedure

Necessary Checks before the alignment

1. Safety Checks;- ensure the isolation of the system from any external source of energy. Remove all the safety guards from the flywheel.
2. Check on Mountings;- Check all the mounting surfaces before installing the instruments.
3. Clean the rust, paint, and dust from the feet and mounting base.
4. Movable component soft foot check;- To avoid the false readings, check the soft foot check. Rectify the soft foot if any soft foot persists.

Alignment Steps (Generator alignment procedures)

1. Attach Brackets;- Attach the brackets to the driven and drive shafts.
2. Install Laser;- Install the Laser to the stationary and the movable ends.

• Alignment Check;- Enter the inputs of the dimension of the equipment and the location points of the Laser and receiver.
• Turn both the equipment 360 degrees to conduct the test.
• Read the reading and follow the steps as per the instrument’s output for the correction of machine positions.
• After the initial adjustments, re-check the alignment.
• Repeat the process of machine position adjustment till we achieve the correct alignment as per the prescribed limits of the manufacturer.
• Carry out the alignment check-in hot condition of the equipment and correct the same. Alignment readings will change in the hot state of the machine.

Conclusion

I hope the post on Generator alignment procedures will be useful to the readers.

Good Luck!!