Siemens Induction Motors/Generators

Table of Contents

• Safety Procedures
• Introduction
• Installation
• Operation
• Maintenance
• Spare Parts
• Motor Service Record
• Vibration Analysis Sheet
• Notes

Safety Procedures

This equipment contains hazardous voltages. Death, serious personal injury or property damage can result if safety instructions are not followed.

The successful and safe operation of motors and generators is dependent upon proper handling, installation, operation and maintenance, as well as upon proper design and manufacture. Failure to follow certain fundamental installation and maintenance requirements may lead to personal injury and the failure and loss of the motor as well as damage to other property.

Only qualified personnel should work on or around this equipment after becoming thoroughly familiar with all warnings, safety notices and maintenance procedures contained herein. Only qualified personnel should be involved in the inspection, maintenance and repair procedure and all plant safety procedures must be observed.

Qualified Person: For the purpose of this manual and product labels, a Qualified person is one who is familiar with the installation, construction and operation of the equipment, and the hazards involved. In addition, he or she has the following qualifications:

1. Is trained and authorized to energize, de-energize, clear, ground and tag circuits and equipment in accordance with established safety practices.
2. Is trained in the proper care and use of protective equipment, such as rubber gloves, hard hat, safety glasses, face shields, flash clothing, etc., in accordance with established safety practices.
3. Is trained in rendering first aid.

Danger: For the purpose of this manual and product labels, Danger indicates an imminently hazardous situation which, if not avoided, will result in death or serious injury.

Warning: For the purpose of this manual and product labels, Warning indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate injury.

Caution: For the purpose of this manual and product labels, Caution indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate injury. It is also used to alert against unsafe practices.

Motors should be installed and grounded per local and national codes.

Do not operate this equipment in excess of the values given on nameplate or contrary to the instructions contained in this manual. The equipment (or a prototype) has been factory tested and found satisfactory for the condition for which it was sold. Operating in excess of these conditions can cause stresses and strains beyond design limitations. Failure to heed this warning may result in equipment damage and possible personal injury.

DANGER Hazardous voltage. Will cause death, serious injury, electrocution or property damage. Disconnect all power before working on this equipment.

Squirrel cage induction machines can be driven by various types of prime movers. These will act as induction generators. This instruction manual applies to both motors and induction generators. However, for clarity reasons, the machine will be referred to as a "motor".

Introduction

DANGER Hazardous voltage. Will cause death, serious injury, electrocution or property damage. Disconnect all power before working on this equipment.

These instructions present general recommendations for installation, operation and maintenance of induction motors built at the Norwood plant. If additional information is required, contact Siemens Industry.

Warranty

See your sales contract for warranty coverage. Documentation of storage maintenance, alignment and regreasing may be required for certain warranty considerations.

Receiving

Motors are shipped in first class condition. They have been inspected and are skidded to prevent damage from ordinary handling during shipment.

Inspect new motors for shipping invoice. Make the examination before removing from cars or trucks. If damage or indication of rough handling is evident, file a claim with the carrier at once, and notify your Siemens sales representative.

Remove only the shipping invoice. Do not remove tags pertaining to lubrication, operation and storage instructions. Read and follow all instructions to insure that no damage to motor bearings, (due to condensation) and motor windings occurs during storage.

Use care in handling. Dropping the motor or otherwise imposing shock loads can cause unseen and undetected damage to bearings. This damage such as false brinelling of the races of anti-friction bearings can result in early bearing failure.

If supplied, energize space heaters to help prevent condensation within the motor enclosure.

Motors having sleeve bearings or oil lubricated antifriction bearings are shipped WITHOUT OIL in the bearing reservoir. These bearings and journal surfaces are protected during shipment by a temporary film of rust inhibiting oil or, when a motor is supplied specifically with “provisions for oil mist lubrication” (oil supply system furnished by the user), the motor is shipped from the factory with grease in the bearings.

When receiving a motor with sleeve bearings:

1. Remove shaft blocking materials.
2. Visually inspect bearing condition through sight glass and bearing drain opening.
3. Check for moisture accumulation. Remove any traces of oxidation before putting the motor into service.
4. Fill bearing reservoirs to normal level with a high grade industrial lubricating oil. See Maintenance Section of this instruction book to determine proper oil level.
5. Rotate the shaft a minimum of 10 complete turns by hand to distribute oil over bearing parts. Make sure the oil rings in each bearing rotate freely.

When receiving a motor with grease lubricated antifriction bearings:

Motors having grease lubricated antifriction bearings are shipped with the bearings already lubricated and ready for operation.

If the elapsed time from the time of shipment to the time in which the unit is to be started is in excess of three (3) months, regrease per the lubrication plate mounted on the motor.

When receiving a motor with oil mist lubricated antifriction bearings:

1. Be sure that the motor is not stored outdoors.
2. Be sure that the oil mist lubrication is connected and operating before starting the motor.
3. The oil mist lubrication should be in operation within two weeks after the motor is received from the factory.

When receiving a motor with "provisions for oil mist lubrication":

1. Leave the grease in the bearings if the motor is to be stored.
2. Before operating the motor with oil mist lubrication, disassemble the motor, and clean the grease from bearings, end caps, and the bearing housing cavities with a suitable solvent.

WARNING Heavy equipment. Improper handling may cause death, serious injury or property damage. Check lifting devices before lifting. Use proper slings, chains and spreaders. Note any warning plates on motor and follow instructions on each plate.

Handling

Lifting devices are provided for handling only. An experienced rigger should be used to install motors.

To avoid damage, the use of spreader bars is recommended on other than single point lifts. Lifting devices are provided to facilitate handling with shackles and cables. Avoid pounding or bumping shaft, coupling or bearing parts, as shocks may damage bearings.

NOTE WEIGHT BEFORE LIFTING. The weight is indicated on the outline drawing. Apply tension gradually to cables. Do not jerk or attempt to move the unit suddenly.

Temporary Storage

If the equipment is not to be installed and operated soon after arrival, store it in a clean, dry, well-ventilated place, free from vibration and rapid or wide variations in temperature. Rotate the shaft a minimum of 10 complete turns by hand each month to coat the bearings with lubricant which will retard oxidation or corrosion, and prevent possible false brinelling.

If drain plugs are provided in enclosed motors, they must be removed periodically to drain any water accumulation from the motor. Consider a unit in storage when:

1. It has been delivered to the job site and is awaiting installation.
2. It has been installed but operation is delayed over 30 days pending completion of plant construction.
3. There are long (30 day) periods between operating cycles.
4. The plant (or department) is shut down for 30 days.

NOTE Storage requirements vary, depending on the length of storage and the climate. For storage periods of three months or longer or climate variations, consult Siemens Storage Recommendations ANIM-03114. Storage maintenance is to be documented for warranty information.

Type Designations

The motor type designation consists of a basic letter or letters indicating the motor enclosure type to which other letters may be added denoting modifications.

Ventilation

Type CG, NCG - 500 Frame

Ventilating air enters through the louvered openings in bearing housings on both ends of the motor. Non-metallic air baffles direct air to the rotor fans and through the rotor core. The air is circulated around the stator coil ends, into the air gap, and through the vent ducts in the rotor and stator cores. The air is exhausted out of the motor through the louvered openings on both sides of the motor. Refer to motor outline drawing for specific air intake and exhaust locations.

Type CG, - 580, 680, & 800 Frame and Type CGII, NCGII – 500, 580, 680, & 800 Frame

Ventilating air enters through both sides of the top enclosure. Non-metallic air baffles direct air to the rotor fans and through the rotor core. The air is circulated around the stator coil ends, into the air gap, and through the vent ducts in the rotor and stator cores. The air is exhausted out of the motor through the openings on both sides of the motor. Refer to motor outline drawing for specific air intake and exhaust locations.

Type CG-1120 Frame

Ventilating air enters through one end of the top cover. A single rotor fan pulls the air through the rotor and stator cores. The air is circulated around the stator coil ends, into the air gap, and through the vent ducts in the rotor and stator cores. The air is exhausted out of the motor through the top cover on both sides of the motor. Refer to motor outline drawing for specific air intake and exhaust locations.

Type CGII - 1120 Frame

Ventilating air enters through both sides of the top cover. A single rotor fan pulls the air through the rotor and stator core. The air is circulated around the stator coil ends, into the air gap, and through the vent ducts in the rotor and stator cores. The air is exhausted out of the motor through the openings on both sides of the motor. Refer to motor outline drawing for specific air intake and exhaust locations.

Installation

Motor Dimensions

For motors built in the frame sizes covered by this manual, the letter dimensions have the same definitions as established NEMA standards. Established dimensions for these frames may be found on catalog sheets or certified drawings.

CAUTION Damp Location. Can cause property damage if equipment is operated intermittently. Use space heaters to prevent dampness. Grease machine fits when unit is reassembled to prevent corrosion.

Location

Select a location for the motor and driven unit that will:

1. Be clean, dry, well ventilated, properly drained, and provide accessibility for inspection, lubrication and maintenance. Outdoor installations may require protection from the elements.
2. Provide adequate space for motor removal without shifting the driven unit.
3. Permit the motor to safely deliver adequate power. Temperature rise of a standard motor is based on operation at an altitude not higher than 3,300 feet above sea level.
4. Avoid condensation of moisture in bearings and on windings. Motors should not be stored or operated in areas subject to rapid temperature changes unless motors are energized or protected with space heaters.

Foundation

Concrete (reinforced as required) makes the best foundation, particularly for large motors and driven units. In sufficient mass it provides rigid support that minimizes deflection and vibration. It may be located on soil, structural steel, or building floors provided the total weight (motor, driven unit, foundation) does not exceed the allowable bearing load of the support.

Allowable bearing loads of structural steel and floors can be obtained from engineering handbooks. Building codes of local communities give the recommended allowable bearing loads for different types of soil. For rough calculation the foundation should be approximately 2-1/2 times total unit weight.

Before pouring, locate foundation bolts by use of template frame and provide secure anchorage (not rigid). It is recommended that a fabricated steel base be used between motor feet and foundation. See certified drawings of motor, base, and driven unit for exact location of foundation bolts. Allow for grouting base when pouring. Cast the base footpads level and in the same plane.

Mounting

Mount the motor base (if used) on foundation or other support. Shim as required to level. Use laser or spirit level (check two directions at 90°) to insure motor feet will be in one plane (base not warped) when base bolts are tightened. Set motor on the base, install nuts and tighten.

DO NOT TIGHTEN UNTIL AFTER ALIGNMENT.

NOTE Experience has shown that any base-mounted assemblies of motor and driven units temporarily aligned at the factory may twist during shipment. Therefore, alignment must be checked after mounting. Realignment is to be documented for warranty information.

Coupling of Sleeve Bearing Motors

Sleeve bearings cannot withstand externally generated axial thrust. Antifriction bearings are normally designed to handle a minimum thrust. As the motor and driven equipment get hot they may expand towards each other and with the wrong coupling this could produce an axial force. Therefore, the selection of coupling is of extreme importance. If properly installed, the following types of couplings are considered to be free from the development of axial thrust and may be used:

1. Laminated Metal Disk Type
2. Rubber Biscuit Type (Designed for the Speed)

Limited end float models of the following types are available from several coupling manufacturers and may be used by selecting the proper end float (See "End Float - Sleeve Bearings" under Bearing Replacement)

1. Pin and Bushing Type
2. Gear Type

External Wiring

DANGER Hazardous voltage. Will cause death, serious injury, electrocution or property damage. Disconnect all power before working on this equipment.

NOTE Before running motor, see Initial Start.

Starting and overload control devices must be matched to motor rating. For safety or convenience they may need to be installed some distance from the motor. Follow the control manufacturer's instructions to make proper installations and connections. Observe the following:

1. Connect electrical power supply to conform with National Electric Code and any local regulations. Line voltage and wire capacity must match motor rating stamped on the nameplate.
2. With the driven equipment disconnected, momentarily energize the motor to check rotation.
3. If motor is three-phase type, reverse rotation (if required) by interchanging any two of the three power leads.

Changing Direction of Rotation

Look for rotation plates usually mounted on opposite drive end of the motor.

CAUTION Excessive heat. Motor may overheat if motor cooling fans run in the wrong direction. Run motor in direction shown on motor or change fans.

The internal rotor fan direction must be considered if changing direction of rotation. See the following Internal Rotor Cooling Fan table to identify which motors have directional fans.

1. Inspect rotor to determine whether alternative A or B below applies;

A. If the rotor has integrally cast directional fans, either rotor machining instructions and conversion parts can be purchased from the factory or the rotor core may be removed from the shaft, switched end-for-end, and remounted on the shaft.

B. If the rotor has shaft-mounted directional fans, the fans must be interchanged end-for-end. Replace single directional rotor fan with one for the opposite direction.

Fans are bi-directional which allows motor rotation in either direction without mechanical modification.

The single directional rotor fans must be interchanged end-for-end.

NOTE It will be necessary to rebalance the rotor if the fans are changed.

Alignment

Accurate shaft alignment between motor and driven equipment is essential. Improper alignment may result in vibration, bearing overloads and excessive shaft stresses. Flexible couplings will not compensate for excessive misalignment.

NOTE A basic rule is to not have more than five shims in a shim pack under any one motor foot. Thick shim packs consisting of many thin shims will cause soft foot, excessive vibration or twisted frame (motor foot out of plane).

Parallel Alignment

After positioning unit for correct end float, separate the coupling halves and mount a dial indicator rigidly on one coupling half with the button on the cylindrical surface of the other half. Rotate the shafts together, and take readings at top, bottom and side positions. Align shaft so difference between top and bottom readings and the side readings is a maximum of 0.002 inch for a flexible coupling.

Angular Alignment

Hold each shaft at maximum end float. Rotate both shafts together, and measure between matching points at the outside diameter of the coupling faces for the top, bottom and both sides. Use two indicators because of possible axial shaft movement. Read difference of variation between them.

Align shafts so that the total indicator variation does not exceed 0.002 inch. (See Figure 1.)

NOTE If vibration levels increase cold to hot, alignment should be checked hot to verify that motor and driven equipment are properly aligned at operating temperature. Adjust if necessary.

Figure 1. Diagrams Showing Parallel and Angular Misalignment

Foot Plane

The proper foot plane exists when adequate shims have been installed to assure equal pressure on each foot or corner of motor when the mounting bolts are loose.

To determine proper foot plane:

1. Mount dial indicator on shaft to be checked so that contact will rest on either the adjacent shaft or a bracket from the foundation or base.
2. With mounting bolts tight and indicator set at zero, release one bolt at the shaft extension end of the unit and check indicator for a maximum change of 0.001 inch.
3. If no change is indicated, retighten the bolt and repeat the process for each of the remaining three mounting bolts.
4. If a change is indicated, add shims under motor foot and retighten until indicator movement is reduced or eliminated.

NOTE

1. The foot plane is of concern for each unit of rotating equipment. Check driven equipment if necessary.
2. Base or foundation rigidity can also affect vibration; check for resonance in supporting structure.
3. Recheck alignment after any change in shims and document alignment readings for warranty information.

V-Belts

Check belt manufacturer's recommendations for maximum speed of sheaves and belts, minimum pitch diameters, maximum allowable number of belts and maximum sheave width.

When motor is ordered for V-belt drive, check motor outline for motor manufacturer's limits on belt pull, sheave distance from motor, and sheave diameter.

Use only matched-belt sets. V-grooves must be in line; sheaves must be parallel and axially aligned. Belts must enter and leave sheaves with no side bending. For long bearing life, the belt tension is important; consult belt manufacturer for proper tension to suit drive. Protect belts from grease and oil. NEVER use belt dressing.

Hot Alignment

It is possible for the motor shaft height to change relative to the driven equipment and this should be compensated for during the alignment procedure. Heat from driven equipment can also cause horizontal misalignment.

WARNING Rotating parts. Can cause serious injury. Disconnect and lock out power before working on equipment.

If motor application is abnormal (high temperature, extreme vibration, etc.) consult the factory for special instructions or additional information.

Vertical Alignment (Parallelism)

Check for vertical alignment (parallelism) of coupled drive as follows:

1. Operate unit until normal temperature is reached (may require several hours).
2. Shut down motor and lock out switch.
3. Mount dial indicator as in Figure 2.
4. Rotate shaft, noting readings at 0°, 90°, 180°, and 270° (both sides, top, and bottom). If within 0.002 inch total indicator reading, or other limit specified by the factory, unit is satisfactory for operation.
5. If not within limits, add or remove shims as required to raise or lower motor.
6. If shims are changed for high temperature operation, repeat alignment procedure to extent necessary to assure proper alignment. Document readings for warranty information.

Figure 2. Check of Vertical Alignment

Vibration

The standard unfiltered housing vibration limits measured at no load, uncoupled, and with rigid mounting are as follows based on the requirements of NEMA MG1-7.8.

After alignment is complete and foot mounting bolts are tight, run motor at no load (or minimum possible). Check for vibration. If excessive vibration exists and the alignment is acceptable, check foot plane by loosening one drive end-mounting bolt at a time as detailed below. This is to be documented for warranty information. When resiliently mounted, allowed levels are 25% higher.

Completing Mechanical Installation

After controlling rotor end float and establishing accurate alignment, it is recommended to drill and ream the foundation plate and motor feet together for dowel pins. (See Doweling).

Recheck parallel and angular alignment before bolting the coupling together. Motor shaft should be level within 0.03 inch after alignment.

Doweling

Doweling the motor (and driven unit) accomplishes the following:

1. Restricts movement.
2. Eases realignment if motor is removed from base.
3. Temporarily restrains the motor, should mounting bolts loosen.

Inserting Dowel Pins

The following procedure is recommended:

1. Check the alignment after the unit has been in operation approximately one week. Correct as necessary.
2. Using pre-drilled dowel holes in motor feet as guides, drill into the mounting base.
3. Ream holes in the feet and base to the proper diameter for tapered dowel pins. Clean out the chips.
4. Insert dowel pins.

Force Feed Lubrication

If force feed lubrication is used, flush lubrication lines thoroughly to make sure the lines are clean before connecting lines to bearing housings. Be sure that bearing cavities are filled with oil to the proper level before starting. See motor outline drawing to determine proper oil level. Be sure that proper oil pressure and flow are provided by the supply system. Verify that the oil drain flow agrees with the factory requirements. The orientation and size of oil drain piping supplied with the motor must not be altered. Oil drain piping should be of the same size or larger from the motor piping to the oil sump. Piping must slope downward. Pressure build up in the drain line between the oil sump and the motor bearing housing can lead to oil leakage. Document readings for warranty information.

Operation

Initial Start

CAUTION Do not exceed number of Siemens specified hot and cold starts per hour. Will cause overheating. Allow time between starts to permit stator windings and rotor cage to cool.

NOTE If motor has been out of service or in storage for more than 30 days, consult Siemens Storage Recommendations ANIM-03114, Preparation for Service

After installation is completed, but before motor is put in regular service, make an initial start as follows:

1. Check that motor, starting, and control device connections agree with wiring diagrams.
2. Check that voltage, phase, and frequency of line circuit (power supply) agree with motor nameplate.
3. Check motor service record and tags accompanying motor. Be certain bearings have been properly lubricated and oil wells are filled. See motor outline drawing to determine proper oil level.
4. If possible, remove external load (disconnect drive) and turn shaft by hand to assure free rotation. This may have been done during installation procedure; if so, and conditions have not changed, this check may not be necessary.
5. If drive is disconnected, run motor at no load long enough to be certain that no unusual condition exists. Listen and monitor for excessive noise, vibration, clicking or pounding and that oil rings are turning if so equipped. If present, stop motor immediately. Investigate the cause and correct before putting motor in service.
6. If drive cannot be disconnected, interrupt the starting cycle after motor has accelerated to low speed. Carefully observe for unusual conditions as motor coasts to a stop. Repeat several times if necessary. Refer to motor's Starting Duty nameplate (if so equipped) or Motor Data Sheet for recommended number of starts and cooling period between starts.
7. When checks are satisfactory, operate at lowest load possible and look for any unusual condition. Increase load slowly to maximum, checking unit for satisfactory operation.

Oil Circulating Systems

For motors with oil circulating systems, proceed as follows before startup;

1. Fill motor reservoirs to normal level (see motor outline drawing).
2. Follow instructions provided by the oil circulating system supplier.
3. Put oil circulating system into operation before starting motor.

Normal Operation

Start the motor in accordance with standard instructions for the starting equipment used. Sometimes the load should be reduced to the minimum, particularly for reduced voltage starting, and/or high inertia connected loads.

Motors will operate successfully under the following conditions of voltage and frequency variation, but not necessarily in accordance with the standards established for operating under rated conditions:

1. If the variation in voltage does not exceed 10% above or below rated voltage, with all phases balanced. Voltage unbalance should not exceed 1%.
2. If the variation in frequency does not exceed 5% above or below rated frequency.
3. If the sum of the voltage and frequency variations does not exceed 10% above or below rated values provided the frequency variation does not exceed 5%.

Trouble Shooting

Between regular maintenance inspections, be alert for signs of motor trouble. Common symptoms are listed in the following table. Correct any trouble immediately and AVOID COSTLY REPAIR AND SHUT DOWN.

DANGER Hazardous voltage. Will cause death, serious injury, electrocution or property damage. Disconnect all power before working on this equipment.

Maintenance

Preventive Maintenance

Motors are designed to give many years of reliable service with a minimum of attention. Trouble-free operation cannot be expected if proper maintenance is postponed or neglected.

Provide proper maintenance on the equipment. Follow carefully the instructions contained herein. Be certain personnel review, understand, and follow these procedures during periodic maintenance inspections.

DANGER Hazardous voltage. Will cause death, serious injury, electrocution or property damage. Disconnect all power before working on this equipment. Maintenance should be performed only by qualified personnel.

CAUTION Flying dirt, dust or other particles. May cause eye injury. Wear safety glasses and dust mask when using compressed air.

CAUTION Loose parts or fire. Can result in product failure or serious property damage.

Maintenance Checklist

1. Verify motor is clean and verify that stator and rotor ventilation passages are unobstructed.
2. Check for excessive loading or service factor.
3. Verify winding temperature rise not in excess of rated value.
4. Verify insulation resistance is above recommended minimum.
5. Verify voltage and frequency variation.
6. Check air gap.
7. Verify that bearing temperatures are within limits and that lubricant is clean and proper level maintained.
8. Verify no unusual vibration or noise exists.
9. Check alignment.
10. Check for proper lubrication.

A definite schedule of preventive maintenance inspections should be established to avoid breakdown, serious damage and extensive downtime. The schedule will depend on operating conditions and experience with similar equipment. To assure adequate maintenance, and warranty consideration, it is essential that complete records be kept for each motor, including description and rating, maintenance schedule and repairs required or carried out.

This checklist does not represent an exhaustive survey of maintenance steps necessary to ensure safe operation of this equipment. Particular applications may require further procedures. Should further information be desired or should particular problems arise which are not covered sufficiently for the purchaser's purposes, the matter should be referred to the local Siemens Sales Office.

WARNING Improper maintenance can cause death, serious injury or property damage. Use only factory authorized parts for repair of equipment. Maintenance should be performed only by qualified personnel.

Inspection

Each motor should be inspected at regular intervals. The frequency and thoroughness will depend on the operating hours, nature of service, and the environment.

Antifriction Bearing

Access to the motor interior can be gained by removal of the bearing housing.

1. Remove the bolts holding the inner bearing end cap to the housing.
2. Remove the bolts holding the bearing housing to the yoke.
3. Remove the bearing housing by pulling it away from the face of the yoke. See Air Deflector.

Sleeve Bearing – 500, 580, 680, 800 Frames

Access to the motor interior can be gained by removal of the upper half of the horizontally split bearing bracket.

1. Remove the parting bolts at the horizontal split.
2. Remove the bolts at the outer circumference of the upper half of the split-bearing bracket.
3. Pull the upper bracket away from the face of the frame and remove bracket.

The entire procedure can be done without disturbing the bearing enclosure or coupling alignment of the motor to the load. The split-bearing capsule is held together by bolts.

Sleeve Bearing - 1120 Frames

Access to the motor interior can be gained by removal of the bearing bracket as follows:

1. Remove the parting bolts at the horizontal split.
2. Carefully remove the top half of the bearing housing by lifting it straight up and then pull it away from the lower half.

Air Deflector

Air deflector construction depends on the type and size of motor. The following conditions will be found when accessing the motor interior;

1. 500 frame motors have air deflectors that are retained in the fit between the bearing housing and the stator yoke. Such air deflectors will be removed with the bearing housing or can be easily removed from the stator yoke after bearing housing removal.
2. 580, 680, 800, or 1120 frame motors have air deflectors which are mounted with bolts to the stator yoke.
3. Air deflectors on sleeve bearing motors are horizontally split.

Cleanliness

The exterior should be kept free of oil, dust, dirt, water, and chemical. It is particularly important to keep the air intake and exhaust openings free of obstructions.

NOTE If equipment is operated intermittently in very damp locations, it should be protected by space heaters. To retard corrosion, grease all machined fits when the unit is reassembled after a maintenance check.

Loading

Overloading causes overheating and reduces insulation life. A winding subjected to a 10°C temperature rise above the maximum limit for its class may have its insulation life halved.

Underloading a motor is improper as it lowers the motor power factor and efficiency which results in higher power cost.

Temperature

Electrical apparatus operating under normal conditions becomes quite warm. Although some places may feel hot to the touch, the unit may be within limits. If checking total temperature by winding resistance or imbedded detector (RTD), the total temperature should not exceed the following:

These temperatures represent the maximum temperature for each class of insulation and include a 40°C ambient temperature. Operation above these temperatures will result in reduced insulation life.

Vibration

Most problems can be detected when inspected visually. Check for;

1. Loose or missing parts, such as fan blades, nuts, bolts, screws, couplings, etc.
2. Accumulation of dirt on fan or rotor.
3. Associated equipment - Disconnect equipment to determine where the vibration is being generated.
4. Foundation construction - Base, grouting and associated equipment supporting drives must be in good condition. Vibration can be amplified by weak construction. Vibration of base just below motor feet should not exceed 25% of motor vibration.
5. History - When was vibration first noted? Was there a change in loading and/or duty of equipment? Has ambient vibration changed?

More important than the actual vibration is the vibration change over a period of time.

Corrective Maintenance

Two factors that require corrective maintenance are electrical failure or mechanical failure. The first sign of electrical failure is usually low insulation resistance. Mechanical failures are usually preceded by excessive bearing noise or heat.

Low Insulation Resistance

Factors that usually cause low insulation readings are:

1. Dirty windings (oil, dust, grease, salt, etc.).
2. Excessive moisture.
3. Mechanically damaged insulation.
4. Heat deterioration

Dirty windings can be cleaned and moist windings dried; however, items 3 and 4 require extensive repairs by a certified service center.

CAUTION Flying dirt, dust or other particles. May cause eye injury. Wear safety glasses and dust mask when using compressed air.

Cleaning

Clean the inside and outside of the motor regularly. Actual conditions existing around the motor dictate the frequency of cleaning operations. Use the following procedures as they apply.

1. Wipe off dust, dirt, oil, water, etc., from external surfaces of the motor. These materials can work into or be carried into the motor windings and may cause overheating or insulation breakdown.
2. Remove dirt, dust, or other debris from ventilating air inlets and exhausts. Do not operate motor with air passages blocked or restricted.

Rotor Cleaning

Remove rotor. Inspect air vents and remove any obstructions.

Stator Cleaning

MICLAD™ form wound VPI (vacuum pressure impregnated) insulated coils may be cleaned with a quick drying solvent and lint free cloths or steam cleaned with low-pressure steam, then the entire stator oven baked at 200°F for 12 hours and then 230°F for 12 hours.

The stator winding insulation resistance should be measured before and after any cleaning operation.

The windings may be cleaned with a solvent compatible with the insulation system and oven dried. Water and detergents with an oven drying cycle may be used as an alternate on MICLAD™ VPI insulation systems.

MICLAD™ is a Siemens trademark.

DANGER Hazardous voltage. Will cause death, serious injury, electrocution or property damage. Disconnect all power before working on this equipment.

CAUTION High Voltage. May damage semi-conductors, small transformers, voltage regulators, and other devices. Disconnect from circuit before testing insulation resistance.

Insulation Resistance

Check insulation resistance periodically. Use a hand cranked or solid state insulation resistance tester and test with at least 500 volts, but not greater than motor rated voltage.

For motors with newer insulation systems such as MICLAD™ VPI, the insulation resistance after one minute should be greater than 1000 megohms. (Values in excess of 5000 megohms are common.) For older motors, the minimum value recommended in IEEE Standard 43 can be used. The value in megohms, when corrected to 40°C, is equal to the motor rated voltage in kilovolts plus 1. For example, for a motor with a rated voltage of 2300 volts, the limit value would be: 2.3 + 1 = 3.3 (megohms).

Drying Insulation

If the insulation resistance is less than satisfactory, and the cause is believed to be excessive moisture in the windings, dry the windings by applying heat from:

1. A warm air oven.
2. Electric strip heaters.
3. Circulating currents through the coils.

The heat should be applied slowly so the desired temperature will not be obtained in less than six hours.

*Class "F" and "H" insulated units should be baked at 70% specified temperature (to avoid steam inside winding) for about six hours, before temperature is raised to drying temperature.

Insulation resistance should be measured before the heat is applied, and every six to eight hours thereafter.

NOTE Insulation resistance will decrease as the motor warms up; but will begin to increase as the drying process continues.

A uniform temperature must be maintained in the motor to obtain constant resistance readings. When the megger readings remain constant, the drying process is complete and may be discontinued. Check for other causes if readings are still low.

Warm Air Oven Drying

1. Remove bearing housings.
2. Remove rotor.

Bake in oven at temperatures specified in Insulation Drying Temperature table, and follow procedures described for drying insulation.

Electric Strip Heater Drying

1. Remove bearing housings.
2. Remove rotor.
3. Direct a fan on stator to carry away the moisture.
4. Attach temperature indicators to winding and apply heat as specified in the Insulation Drying Temperature table and follow procedures described for drying insulation.
5. Radiant type heaters are not recommended because some parts may become scorched before remote parts reach desired temperature.

Circulating Current Drying

1. Remove bearing housings.
2. Center the rotor in the stator core.
3. Wedge fiber strips into the lower part of the air gap so rotor does not touch stator core, or remove rotor.
4. Direct fan on unit to blow away excessive moisture.
5. Attach temperature indicators to windings. Do not exceed the drying temperatures in the Insulation Drying Temperature table.
6. An external source of current can be used to circulate direct current through the winding of any type of alternating current motor. A portable low voltage motor-generator set, such as is used for welding, is usually suitable.

CAUTION High temperatures. May cause damage to insulation. Avoid hot spots and radiant type heat

Bearing Construction

Two types of bearings are employed in induction motors. These are:

1. Antifriction bearings.
2. Sleeve bearings.

The type of bearing mounting and supporting structure will depend upon the type of bearing. Bearing housing construction will also vary with the type of bearing. Antifriction bearing motors have one piece bearing bracket construction. Sleeve bearing motors have split bearing housings.

Insulated Bearings

One or both bearings may be insulated to prevent shaft currents from pitting bearing surfaces. The insulation is located at the joint between the bearing housing or bracket and the bearing. Insulated bearings are designated by an instruction plate on the bearing housing.

Check periodically to be sure the insulation has not been weakened or destroyed.

The bearing insulation can be checked using an ohmmeter or circuit test light. For sleeve bearing motors with one bearing insulated, the shaft must be raised a few mils at the non-drive end of the motor so that it is not in contact with the bearing and the shaft coupling must be parted so that the shaft is not grounded through the driven equipment. For motors with both bearings insulated, disconnect bearing grounding strap before testing for insulation integrity. Bearing temperature devices must be disconnected and oil rings must not be in contact with both the shaft and the bearing.

Antifriction Bearings

Antifriction bearings are selected to give long service when they are given proper maintenance. Bearing failure can be caused by too little or too much lubrication, contamination, excessive bearing load, improper installation, alignment, or vibration.

The symptoms of antifriction bearing failure are excessive vibration, noise, and excessive heat generation. The races and balls should be periodically inspected for damage. Any damage requires replacement of the bearing.

Sleeve Bearings

Check sleeve bearings daily to be sure the oil rings are turning properly. See motor outline drawing to determine proper oil level. Add oil through the oil ring sight glass opening or oil inlet pipe, if so equipped. Be careful not to overfill.

Drain the oil reservoir by removing pipe plug. Clean and flush with solvent and refill with fresh filtered oil every three months to one year, depending on severity of service. Use a high grade turbine oil having a viscosity of 300-350 SSU at 100°F for units of 1800 rpm and lower, and 140-160 SSU at 100°F for machines above 1800 rpm to 3600 rpm.

In addition, seasonal oil changes are desirable if unit is subject to wide variations in temperature.

Bearing babbitt temperatures that exceed 90°C (194°F) or a sudden rise in temperature should be investigated.

Common causes of hot bearings are:

1. Lack of oil.
2. Incorrect viscosity.
3. Poor quality oil.
4. Inoperative oil ring.
5. Misalignment of couplings or bearings.
6. Insufficient bearing clearance.
7. Oil seal rubbing on shaft.
8. Shaft or bushing rough spots.
9. Plugged oil passages on circulating oil systems. (Note that circulating oil systems include a filter in the oil line to strain the oil after it leaves the pump. Check and clean or replace filter when necessary.)
10. End thrust on bearing face.

Sleeve bearings are bored to an even dimension and shaft journals are slightly smaller to obtain running clearance. Side reliefs are provided to distribute oil axially and reduce friction. During normal operation, the shaft is supported on an oil film 0.001 to 0.005 inch thick, depending on speed, load and viscosity. Unless adverse conditions exist which tend to break down the oil film, metallic contact occurs only during starting and stopping. Under normal circumstances, bearing wear is very small.

Oil Rings

Inspect oil level and oil ring operation frequently. Oil ring operation can be observed through the oil sight glass. Oil rings should be perfectly round, free of burrs or rough edges, turn at a constant speed, and carry a noticeable amount of oil to the top of the bearing journal. Failure of the oil ring to turn freely may be caused by:

1. Ring out of round - rings should be round within 0.062 inch.
2. Fouling on a projection of the bearings, bushing, or housing.
3. Ring not balanced (heavy side will tend to remain down).
4. Adhesion to guide slot (trapezoidal section reduces adhesion).
5. Oil too cold, too viscous, or oil level too high.
6. Shaft not level – oil ring tends to bind.
7. Vibration causing oil ring to bounce and slow down.

Sealing Parts

Even though joints may seem to match perfectly, minute clearances exist through which oil may leak.

Apply sealant as follows:

1. Surfaces shall be clean of dirt, grease, and oil sealant. Use a non-oil base solvent if necessary.
2. The mating surfaces should be flat with no nicks raised above the surface. There should be no gap when mating surfaces are together.
3. For 500, 580, and 1120 frames, apply a small bead of silicone RTV at the bearing housing parting surfaces. Loctite 518 may be used in replace of RTV in environments where silicon is prohibited. Do not apply too much sealant as excess will be squeezed out and get into labyrinth seals, bearing, oil cavities, etc. Apply a uniform, thin layer (about 0.05" thick) of Curil T* to the floating oil seal surfaces that mate with the bearing housing. Allow Curil T to cure on the seals for 15 minutes before insertion into bearing housing.
4. For 680 and 800 frames, apply a small bead of silicone RTV to all mating surfaces of parts where oil is present, including fixed oil seals and parting lines.
5. Assemble parts.

*CURIL-T may be ordered through Siemens Customer Service in Norwood, Ohio. Part number 53-688-487-001 should be used for ordering purposes.

Bearing Lubrication

Grease Lubricated Antifriction Bearings

NOTE A common mistake is over-lubrication of bearings. When grease is added without removing the drain plug, the excess grease may be forced into and through the inner bearing cap and thrown on to the windings. If bearing is over-lubricated, bearing could run hot, and may lead to failure.

All antifriction bearing motors will have an affixed plate with lubricating instructions. The instructions on this plate should be followed to achieve optimum bearing life and to avoid consequential damage to rotating parts.

The frequency of relubricating bearings depends on three factors - speed, type of bearing, and service. Operating environment or application may dictate more frequent lubrication.

Relubricate with the type of grease specified on the lubrication plate mounted on the motor, or a compatible grease. Mixing of non-compatible greases can cause bearing failure.

Higher stator temperatures will result in increased bearing temperatures. Bearing temperatures should not exceed the limits as stated in Typical Motor Control Settings. For specific recommendation, consult factory.

Procedure for relubrication:

1. Stop the motor and lock out the switch.
2. Thoroughly clean the grease inlet fitting or plug. If the motor has plug, remove plug and clean the inlet.
3. Remove the drain plug and clean out any hardened grease.
4. Slowly pump the correct amount of grease into the grease inlet, per the lubrication plate mounted on the motor.
5. Start motor and allow to run at least one (1) hour to expel any excess grease from the drain opening before re-installing the drain plug.
6. Stop the motor and lock out the switch.
7. Re-install the drain plug.
8. Put the motor back in operation.

The amount of grease for bearings may be calculated by the following:

G = 0.1 x D x B

Where: G = Amount of grease in fluid ounces D = Outside diameter of bearing in inches B = Width of bearing in inches

Sleeve Bearings

It is important to maintain the correct oil level, as lack of lubrication is often the cause of bearing failure.

Inspect oil level and oil ring operation frequently. Oil ring operation can be observed through the sight glass mounted at the top of the bearing capsule. Oil rings should be perfectly round, free of burrs or rough edges, turn at constant speed and carry a noticeable amount of oil to the top of the journal. Failure of the oil ring to turn freely may be caused by:

1. Ring out of round (should be round to 0.062 inch)
2. Fouling on a projection of the bearing bushing.
3. Ring not balanced (heavy side will tend to remain down).
4. Adhesion to guide slot (trapezoidal section reduces adhesion).
5. Oil too cold or viscous, or oil level too high.
6. Shaft not level – oil ring tends to bind.

At the first sign of oil discoloration or contamination, replace with new oil. Rapid discoloration is caused by bearing wear, often from vibration or thrust. Change oil as required to keep clean.

Force Feed Lubrication

Oil is metered through an orifice in oil inlet line to allow the proper amount of lubricating oil to enter the bearing. Conventional oil rings are also supplied with the motor to insure temporary bearing lubrication in the event the force feed oil supply should fail. It is important to check oil flow frequently. Lack of lubrication may cause bearing failure.

Checking Sleeve Bearing Clearance

Excessive clearance can cause rapid bearing failure, and decreased air gap between stator and rotor at the bottom of the motor. Diametrical sleeve bearing clearances for the 500, 580, 680, and 800 frame motors are approximately 2 mils per inch of bearing diameter. Diametrical sleeve bearing clearances for the 1120 frame is in the range of 1.5mils per inch of bearing diameter.

An accurate check of bearing clearance is obtained with micrometer measurements of the shaft journal and bearing bore.

Bearing Replacement

Antifriction Bearings

For typical antifriction bearing configuration, see Figure 3.

Replacement bearings may be of a different manufacturer but must be equal to the originals used in the motor. When ordering bearings specify as follows:

1. The complete A.F.B.M.A. (Anti-Friction Bearing Manufacturers' Association) bearing number from the motor nameplate.
2. Identifying numerals and manufacturer stamped on the bearing.
3. Bearing tolerance class, i.e. - A.B.E.C.-1 (Annular Bearing Engineers' Committee Tolerance Class One).
4. Internal radial clearance, i.e. - A.E.B.M.A.-3 (Clearance Class Three).
5. Electric motor quality.

To Replace Antifriction Bearings

1. Remove bolts holding end caps to housings.
2. Remove bolts holding bearing housings to yoke.
3. Remove bearing housings.
4. Remove the bearing with a puller. See Figure 4.
5. Check shaft and housing diameter for proper size with micrometer.
6. Heat the new bearing in an oven (200°F). While it is hot, slide the bearing onto shaft make certain that the inner race makes a firm even contact with shaft shoulder. Do not subject bearing to impact.
7. Let bearing cool pack bearing caps with the proper grease.
8. Reassemble end caps and housings.

The amount of grease to be used when repacking a bearing after cleaning or replacement is shown in the table below.

*Pack all open bearings full between balls or roller but remove excess grease on outside of retainers.

Figure 3. Ball Bearing Construction

Protect the shaft end with a cap. If bearing is reusable, make certain the puller applies pressure against the bearing inner race only. If puller will not hook the bearing inner race, fabricate a split bushing and install it between the bearing and the puller hooks.

Figure 4. Removing Bearing with a Puller

Sleeve Bearing Replacement

The replacement of sleeve bearings can often be accomplished without uncoupling the load or otherwise disturbing the installation.

500 and 580 Frames (See Figure 5)

1. Check replacement bearings for nicks or shipping damage. Do not scrape.
2. Remove the upper half of the bearing bracket. NOTE: For 500 frame, WPII motors, the upper top enclosure must be removed before disassembly of the upper bearing bracket.
3. Carefully remove the top half of the bearing capsule by first lifting straight up, then pulling away from the bearing area. NOTE: The floating oil seals may remain in place during the replacement of the bearing bushing.
4. Remove the top half of the bearing bushing.
5. Remove bearing temperature probes if so equipped.
6. Displace the oil rings axially away from the bottom half of the sleeve bearing.
7. Raise the shaft slightly and support it.
8. Rotate the lower bearing half 180° and remove the lower half of the bearing bushing.
9. Reassemble, reversing the steps above. Apply sealant. (See MAINTENANCE, SEALING PARTS for proper sealing of this bearing design.) Be careful not to disturb or jam the seals when replacing the upper half of the bearing capsule. Carefully line up the anti-rotation key on the oil seals with the keyseat on the bearing capsule.
10. Lubricate. Turn motor by hand to be sure of proper fit and oil ring operation.
11. Start motor without load and check oil ring operation.

Figure 5. Sleeve Bearing Construction with Floating Type Oil Seals - 500 and 580 Frames

680 and 800 Frames (See Figure 6)

1. Check replacement bearings for nicks or shipping damage. Do not scrape.
2. Remove the upper half of the bearing enclosure (bracket).
3. Loosen the inner and outer oil guards and displace them axially a small amount so as to free upper half of bearing capsule.
4. Remove the upper half of the bearing capsule.
5. Remove the top half of the bearing bushing.
6. Remove bearing temperature probes if so equipped.
7. Displace the oil rings axially away from the bottom half of the sleeve bearing.
8. Raise the shaft slightly and support it in that position.
9. Rotate the lower bearing half 180° and remove the lower half of the bearing bushing.
10. Reassemble, reversing the steps above. (See MAINTENANCE, SEALING PARTS for proper sealing of this bearing design).
11. Lubricate. Turn motor by hand to be sure of proper fit and oil ring operation.
12. Start motor without load and check oil ring operation.

Figure 6. Sleeve bearing construction with labyrinth-type oil seals - 680 and 800 Frames.

1120 Frame (See Figure 7)

1. Check replacement bearings for nicks or shipping damage. Do not scrape.
2. Carefully remove the bearing housing cap by first lifting straight up, then pulling away from the bearing area.
3. Remove top half of bearing liner.
4. Remove the bolts at the split line of the oil ring, disengage the dowels, and remove the oil ring.
5. Remove bearing temperature probes if so equipped.
6. Raise the shaft slightly and support it.
7. Rotate the lower bearing half 180° and remove the lower half of the bearing liner.
8. Reassemble, reversing the steps above. Apply sealant. (See MAINTENANCE, SEALING PARTS for proper sealing of this bearing design).Be careful not to disturb or jam the seals when replacing the upper half of the bearing capsule.
9. Lubricate. Turn motor by hand to be sure of proper fit and oil ring operation.
10. Start motor without load and check oil ring operation.

Figure 7. Sleeve Bearing Construction 1120 Frame.

End Float – Sleeve Bearings

Control of rotor end float in sleeve bearing motors is maintained in the drive end bearing. The total end float is 0.5 inch. On the 500, 580, 680 and 800 frames, the bearings are located axially by shims between the bearing bushing and the bearing capsule shoulders. On the 1120 frame, the shims are located between the bearing housing mounting flange and the bearing bracket. The shims permit the bearing to be adjusted axially to maintain coincidence of electrical and mechanical center. Any adjustment of the axial position of one bearing should be accompanied by the same axial adjustment of the opposite end bearing.

The coupling should limit the end float of the shaft to ±0.18 inch from the mechanical center. The limited end float coupling prevents the rotor from rubbing against the bearing shoulders during operation.

Spare Parts

Identification

All units have an identification nameplate affixed to the frame (Figure 8). All the necessary information pertaining to the motor can be found on this plate including;

1. Serial Number
2. Type and Frame Size
3. Horsepower and Speed
4. Bearing Designations

It is important when ordering spare parts or discussing service to have as much data from this plate as possible.

Parts Identification

Figures 9 through 16, are of a standard design. Your motor may differ slightly.

A recommended list of spare parts is available upon request.

Figure 8. Identification Plate

Figure 9. Type CG & NCG, 500 Frame

Figure 10. Type CGII & NCGII, 500 Frame

Figure 11. 500 Frame Sleeve Bearings

Figure 12. Types CG & CGII, 580 Frame

Figure 13. 580 Frame Sleeve Bearings

Figure 14. Types CG & CGII, 680 & 800 Frames

Figure 15. 680 & 800 Frame Sleeve Bearings

Figure 16. Types CG & CGII, 1120 Frame

Motor Service Record

This section provides a template for recording motor details, maintenance history, and inspection records.

Vibration Analysis Sheet

Before vibration difficulties are reported, accurate vibration readings should be taken and consideration given to the following:

1. How does vibration level at center line of motor compare to that at motor feet and foundation?
2. Is motor on a fabricated base or grouted in concrete?
3. When power is cut, does the vibration decay immediately or does it gradually die away?
4. Is there a large shim pack under motor feet?
5. Does vibration level change when mounting bolts are loosened one at a time? Do feet distort when bolts are loosened?
6. Is motor for coupled or belt-drive use? Is a coupling used on a long shaft motor? If so, how long is the key and what is the length of the coupling?
7. Is there a resonant condition in the system which can be checked by a hammer test?

Notes

This section is for recording any additional notes or observations.