C05_Exhibit_1_-_EASA_Standard_AR100-2015.pdf

EASA Standard AR100-2015

R E C O M M E N D E D P R A C T I C E

FOR THE REPAIR OF ROTATING

ELECTRICAL APPARATUS

Recognized as an American National Standard (ANSI)

A N S I / E A S A A R 10 0 - 2 015

EXHIBIT 1

EASA AR100-2015 Recommended Practice - Rev. August 2015

EASA AR100-2015

RECOMMENDED

PRACTICE

FOR THE REPAIR OF ROTATING

ELECTRICAL APPARATUS

Copyright © 2015. All rights reserved.

Electrical Apparatus Service Association, Inc.

1331 Baur Blvd. • St. Louis, MO 63132 USA

314-993-2220 • Fax: 314-993-1269 www.easa.com • easainfo@easa.com ii

TABLE OF CONTENTS

SECTION 1: GENERAL

1.1 PURPOSE

1.2 SCOPE

1.3 IDENTIFICATION

1.3.1 Service Center Labeling

1.3.2 Records

1.3.3 Nameplate

1.4 CONDITION ASSESSMENT AND

FAILURE INVESTIGATION

1.5 INSPECTION AND CLEANING

1.5.1 Inspection

1.5.2 Cleaning

1.6 TERMINAL LEADS

1.7 TERMINAL CONNECTORS

1.8 TERMINAL BOXES

1.9 COOLING SYSTEM

1.10 EXTERIOR FINISH

1.11 PACKAGING AND TRANSPORTATION

1.12 AUTHORIZATION TO SHIP

SECTION 2: MECHANICAL REPAIR

2.1 SHAFTS

2.1.1 Diameter Tolerances

2.1.2 Permissible Runout

2.1.3 Keyseat (Keyway) Width Tolerances

2.2 BEARINGS

2.2.1 Ball or Roller Bearings

2.2.2 Sleeve Bearings

2.2.2.1 Sleeve Bearing End-Thrust

2.2.2.2 Oil Rings

2.2.2.3 Seals

2.3 LUBRICATION

2.3.1 Grease

2.3.2 Oil

2.4 FRAME AND BEARING HOUSINGS

2.4.1 General

2.4.2 Mounting Surface Tolerances, Eccentricity and Face Runout

2.5 LAMINATED CORES

2.5.1 Rotating Elements

2.5.2 Stators

2.6 BALANCING

2.7 SLIP RINGS

2.8 COMMUTATORS

2.8.1 Machining

2.8.2 Undercutting and Beveling

2.9 BRUSHHOLDERS

2.10 BRUSHES

2.11 BRUSH SETTING FOR DC MACHINES

2.12 AIR GAP OF MACHINES

2.13 ACCESSORIES

2.13.1 Capacitors

2.13.2 Starting Components and Switches

2.13.3 Terminal Boards

2.13.4 Space Heaters

2.13.5 Temperature Sensors

TABLES

2-1 Shaft Extension Diameter Tolerances–

NEMA Machines 2-2 Shaft Extension Diameter Tolerances–IEC

Machines 2-3 Permissible Shaft Extension Runout–

NEMA Machines 2-4 Permissible Shaft Extension Runout–IEC

Machines 2-5 Shaft Extension Keyseat Width

Tolerances–NEMA Machines 2-6 Shaft Extension Keyseat (Keyway) Width

Tolerances–IEC Machines 2-7 Labyrinth Seal Diametral Clearance Guide 2-8 Mounting Surface Tolerances, Eccentricity, and Face Runout–NEMA Type C Face- Mounting Motors and Type D Flange- Mounting Motors

2-9 Mounting Surface Tolerances, Eccentricity, and Face Runout–NEMA Type P Flange- Mounting Motors

2-10 Mounting Rabbet (Spigot) Diameter Tolerances–IEC Flange-Mounted Machines

2-11 Mounting Surface Eccentricity and Face Runout–IEC Flange-Mounted Machines

2-12 Brush-to-Brushholder Clearance 2-13 Radial Ball Bearing Fit Tolerances 2-14 Cylindrical Roller Bearing Fit Tolerances

SECTION 3: REWINDING

3.1 INSPECTION

3.1.1 Core Laminations

3.1.2 Thermal Protectors or Sensors

3.2 REWINDING SPECIFICATION

3.3 STRIPPING OF WINDINGS

3.4 INSULATION SYSTEM

3.5 CONDUCTORS

3.6 STATOR, ROTOR, AND ARMATURE

COILS

3.6.1 Random-Wound Coils

3.6.2 Form-Wound Coils

3.7 FIELD COILS

3.7.1 Stationary Coils

Table of Contents, Page 1 iii

3.7.2 Rotating Coils

3.8 SQUIRREL CAGE AND AMORTISSEUR

WINDINGS

3.9 THERMAL PROTECTORS OR SENSORS

3.10 SHAPING AND LACING OF STATOR

WINDINGS

3.11 COIL CONNECTIONS

3.11.1 Making Connections

3.11.2 Insulating Connections

3.12 WEDGES

3.13 BANDING OF ROTORS AND ARMATURES

3.14 IMPREGNATION OF WINDINGS

SECTION 4: TESTING

4.1 SAFETY CONSIDERATIONS

4.2 INSULATION CONDITION INSPECTION

AND TESTS

4.2.1 Insulation Resistance Test

4.2.2 Polarization Index (P.I.) Test

4.2.3 Insulation Power Factor Tests

4.2.4 Turn-to-Turn Test

4.2.5 Winding Surge Test

4.2.6 Interlaminar Insulation Test

4.2.7 Bearing Insulation Test

4.2.8 Phase Balance Test

4.2.9 Polarity Test

4.2.10 Dummy Rotor Test

4.2.11 Impedance Test

4.3 RECOMMENDED WINDING TESTS

4.3.1 Stator and Wound-Rotor Windings

4.3.2 Squirrel Cage Windings

4.3.3 Armature Windings

4.3.4 Shunt, Series, Interpole, Compensating and Synchronous Rotor Windings

4.3.5 Interconnection of Windings

4.4 HIGH-POTENTIAL TESTS

4.4.1 Windings

4.4.1.1 New Windings

4.4.1.2 Reconditioned Windings

4.4.1.3 Windings Not

Reconditioned

4.4.2 Accessories

4.4.2.1 New Accessories

4.4.2.2 Accessories of Machines with

Reconditioned Windings

4.4.2.3 Accessories of Machines with

Windings Not Reconditioned

4.5 NO-LOAD TESTS

4.5.1 Speed

4.5.2 Current

4.5.3 Cooling System

4.5.4 Sound Level

4.5.5 Bearing Temperature

4.5.6 Vibration Tests

4.6 TESTS WITH LOAD

4.7 INSTRUMENT CALIBRATION

TABLES

4-1 High-Potential Test Using AC–New

Windings 4-2 High-Potential Test Using DC–New

Windings 4-3 High-Potential Test Using AC–New

Accessories 4-4 High-Potential Test Using DC–New

Accessories 4-5 Unfiltered Vibration Limits–Resiliently

Mounted Machines

APPENDIX: ELECTRICAL TESTING

SAFETY CONSIDERATIONS

A.1 PERSONAL SAFETY

A.1.1 Training A.1.2 Clothing A.1.3 Supervision A.1.4 First Aid and CPR

A.2 TEST AREA

A.2.1 Enclosure A.2.2 Gates A.2.3 Signs A.2.4 Lighting A.2.5 Safety Equipment A.2.6 Test Unit Clearance

A.3 UNIT UNDER TEST

A.3.1 Suitability for Test A.3.2 Exclusive Attention A.3.3 Grounding (Earthing) A.3.4 Base

A.4 TEST PANELS

A.4.1 Construction A.4.2 Voltages A.4.3 Warning Lights A.4.4 Disconnect A.4.5 Safety Switch A.4.6 Leads

A.5 HIGH-POTENTIAL GROUND (EARTH)

TEST

BIBLIOGRAPHY

STANDARDS ORGANIZATIONS &

OTHER RESOURCES

Table of Contents, Page 2 iv

Section 1 General and a new nameplate mounted adjacent to it with the word “redesigned” and the new rating and date of redesign shown. The original nameplate may be reversed (blank side out) to prevent misinterpreta-tion, but it should remain with the frame.

1.4 CONDITION ASSESSMENT AND

FAILURE INVESTIGATION

The service center should inspect and test the ap-paratus when received to confirm its condition and obtain data for any failure investigation. Initial data collection should proceed before any work is carried out. Inspect all parts for defects before and after cleaning. Document any evidence of distress, such as physical damage, overheating, tampering, inap-propriate lubrication, electrical tracking, or foreign object damage. If possible, obtain information about operating conditions at the time of failure. Collect and carefully examine any debris from any fault.

The primary cause of failure should be determined, if practical, and documented in the repair record.

1.5 INSPECTION AND CLEANING

1.5.1 Inspection

If required clean the external surfaces of the equip-ment to avoid contaminating internal components during disassembly. Disassembly should be done methodically. Record the condition of all components, take dimensions necessary for reassembly, condition assessment and fault diagnosis. Each component should be clearly and indelibly marked so that it can be placed in the correct location upon re-assembly.

It is important to preserve and carefully inspect any material or component that may have been involved in a failure. Inspect all parts for wear and damage before final cleaning.

Insulation should be examined for evidence of degradation or damage, such as:

(1) Puffiness, cracking, separation or discolor-ation as indication of thermal aging.

(2) Contamination of coil and connection surfaces.

(3) Abrasion or other mechanical stresses.

(4) Evidence of partial discharges (corona).

(5) Loose wedges, fillers, ties, banding, or surge rings.

(6) Fretting at supports, bracing or crossings (an indication of looseness or movement).

(Reference: IEEE Stds. 432, Sec. 5.)

Bars and end rings for amortisseur and squirrel cage windings should be examined for evidence of defects. Testing may be needed (see Paragraph 4.3.2).

1.1 PURPOSE

The purpose of this document is to establish recommended practices in each step of the rotat-ing electrical apparatus rewinding and rebuilding processes.

1.2 SCOPE

This document describes record keeping, tests, analysis, and general guidelines for the repair of induction, synchronous and direct current rotat-ing electrical apparatus. It is not intended to take the place of the customer’s or the machine manu-facturer’s specific instructions or specifications or specific accepted and applicable industry standards or recommended practices.

This document should be supplemented by ad-ditional requirements applicable to specialized rotating electrical apparatus including, but not lim-ited to, listed explosion proof, dust-ignition proof, and other listed machines for hazardous locations; and specific or additional requirements for hermetic mo-tors, hydrogen-cooled machines, submersible motors, traction motors, or Class 1E nuclear service motors.

1.3 IDENTIFICATION

1.3.1 Service Center Labeling

Machines or standalone components received for repair should have the repair company’s name or identifying logo and shop order number permanently affixed to machine or standalone components for future reference. This shop order number should be listed on the repair invoice.

1.3.2 Records

A record of each machine received for repair should be established at the time of receipt and kept on file for at least 3 years. The record should include the nameplate data, electrical test data (both before and after repair), mechanical measurements (both before and after repair), original winding data, final wind-ing data, and details of replaced parts. This record should be made available to the customer for review if requested. The primary cause of failure should be determined, if possible, and should be recorded on the apparatus repair record.

1.3.3 Nameplate

An electrical machine should have a permanent nameplate containing the principal information needed to put the machine into service. The original nameplate is preferred. If a machine is redesigned, the original nameplate should remain on the unit

Section 1, Page 1

1.5.2 Cleaning

All windings and parts should be cleaned. Dirt, grit, grease, oil, and cleaning agent residue should be removed. The parts that do not require immedi-ate work should then be clearly labeled to identify the customer or job number and stored to prevent damage, contamination or corrosion.

1.6 TERMINAL LEADS

All apparatus equipped with lead wire should have insulated lead wire that meets or exceeds machine rated current, temperature class and voltage. The temperature rating should be appropriate for the duty and any oven curing process, and allow for the effect of heat transfer to the terminals.

All leads should be suitably marked or colored where necessary to indicate correct connection. Lead markings should conform to original manufacturer markings, NEMA Stds. MG 1 or IEC Stds. 60034-8, whichever is applicable.

Leads and markings should be of sufficient du-rability to withstand the environment involved and be of sufficient length for ease of connecting to power supply at the terminal box or to terminal blocks. Leads on totally enclosed apparatus should be properly sealed to meet environmental operating conditions.

A print or plate should be furnished, where neces-sary, indicating correct connections.

1.7 TERMINAL CONNECTORS

The recommended method of attaching terminal connectors (lugs) to lead wire is by crimping or pressure indenting the lug barrel, using a lug sized to suit the particular cable stranding provided, in accordance with recommendations of the lug manu-facturer.

Damaged or missing lugs should be repaired or replaced.

1.8 TERMINAL BOXES

Missing terminal boxes should be replaced, and damaged terminal boxes should be repaired or re-placed. See NEMA Stds. MG 1, 4.19 for guidance on replacement terminal boxes. Gaskets and seals that are removed should be replaced.

1.9 COOLING SYSTEM

The fans and cooling ducts should be clean and operational. Cover plates and air baffles should be clean and in place. Damaged or missing parts of the cooling system should be repaired or replaced.

1.10 EXTERIOR FINISH

Apparatus should be externally cleaned and painted, unless the customer requests otherwise.

1.11 PACKAGING AND

TRANSPORTATION

After completion of the repair and testing, the ma-chine should be packed in a manner suitable for the form of transport to be used. Packing and transport should be as arranged with the customer. Blocking of the shaft is recommended, depending on the type of machine, mode of transport and the distance to be traveled. Where blocking is used, it should be clearly identified. Oil-lubricated machines should be shipped without oil, and the need for lubricant clearly identified.

1.12 AUTHORIZATION TO SHIP

Repaired machines that have passed all required repair related tests and inspections should have the indication of acceptability, for example, “OK to ship” entered in the repair record. The service cen-ter should identify those authorized to make this determination.

Section 1, Page 2

Section 2 Mechanical Repair manufacturer’s specifications if available. Other-wise, the values in Table 2-7 are provided as a guide.

Measure the final seal dimensions.

2.3 LUBRICATION

2.3.1 Grease

If bearings require grease lubrication, grease in-lets should be equipped with fittings and the inlet passages and tubes cleaned and filled with appropri-ate grease. Lubricant should be compatible with the customer’s lubricant. Open bearings should be filled with grease during assembly.

In the absence of the machine manufacturer’s lubrication instructions, the grease reservoir should be filled to approximately 1/3 capacity.

2.3.2 Oil

Lubricant, including oil for test operation, should be compatible with the customer’s lubricant. There should be a means to indicate proper oil level, such as an oil sight gauge. Evidence of oil leaks should be investigated and the cause corrected.

2.4 FRAME AND BEARING HOUSINGS

2.4.1 General

Frame and bearing housings should be examined for defects. Cracks and breaks should be repaired and fits restored to manufacturer’s specifications.

2.4.2 Mounting Surface Tolerances, Eccentricity and Face Runout

• NEMA Type C face-mounting motors and Type D flange-mounting motors: See Table 2-8.

• NEMA Type P flange-mounting motors: See Table 2-9.

• IEC flange-mounted machines: See Table 2-10 and Table 2-11.

2.5 LAMINATED CORES

Examine stator and rotating element laminations for evidence of hot spots, physical damage or miss-ing components.

2.5.1 Rotating Elements

Inspect rotating element core for evidence of loose fit on the shaft, sleeve or spider on which the lamination stack is assembled. The outer diameter of the rotating element laminations should be true and concentric with the bearing journals.

2.5.2 Stators

The stator laminations should not be loose in the frame. If applicable, the bore of the stator lamina-tions should be true and concentric with the rabbet

2.1 SHAFTS

Shafts should be checked for wear, cracks, scoring and straightness. Shaft extension dimensions should be checked as follows.

2.1.1 Diameter Tolerances

• NEMA frame size machines: See Table 2-1.

• IEC frame size machines: See Table 2-2.

2.1.2 Permissible Runout

• NEMA frame size machines: See Table 2-3.

• IEC frame size machines: See Table 2-4.

2.1.3 Keyseat (Keyway) Width

Tolerances

• NEMA frame size machines: See Table 2-5.

• IEC frame size machines: See Table 2-6.

Keyseats should be true and accommodate keys to a tap fit.

2.2 BEARINGS

Bearings should be inspected for failure modes such as spalling, contamination, fretting, fluting, and scoring. Bearings and bearing arrangements should be identified and documented. Insulated bearings should be tested (see 4.2.7).

2.2.1 Ball or Roller Bearings

Bearing housing and shaft bearing fits should be measured and compared to design specifications (Reference: ANSI/ABMA Stds. 7 as a guide). Any fits that are not within tolerance should be restored.

See Tables 2-13 and 2-14. Replacement bearings should be equivalent to the original manufacturer’s specifications unless redesigned by agreement with, or at the instruction of the customer.

2.2.2 Sleeve Bearings

The sleeve bearing fit in the housing and the diametral clearance should be measured and set to original equipment manufacturer’s specifications if available. Note: Not all sleeve bearing bores are cylindrical.

2.2.2.1 Sleeve Bearing End-Thrust

Bearings of horizontal machines should be posi-tioned on the shaft to eliminate end-thrust against either bearing.

2.2.2.2 Oil Rings

Oil rings should be true and rotate freely. Retain-ers, when provided, should be inspected and replaced if necessary.

2.2.2.3 Seals

Seal clearance should be set to original equipment

Section 2, Page 1

(spigot) diameter of the frame.

2.6 BALANCING

Dynamic balancing of the rotating element should be to the level specified by the customer. In the absence of a requested level, dynamic balancing to balance quality grade G2.5 (ISO 1940/1) for ma-chines rated 2500 rpm or slower, and to the level of grade G1.0 for machines rated above 2500 rpm should enable the machine to meet final vibration limits as defined in Paragraph 4.5.6.

Note: Locate balance weights so that they do not interfere with other components.

2.7 SLIP RINGS

The slip rings should be turned to concentricity with the shaft bearing seats.

The surface finish should be between 40 and 60 micro-inches (1.02 and 1.52 microns). For those de-signs where the slip rings are equipped with a spiral groove to reduce brush operating temperature, both edges of the groove should be lightly chamfered.

Slip rings should have sufficient stock to ensure proper brush performance. Manufacturer’s limits should apply.

2.8 COMMUTATORS

2.8.1 Machining

The commutator should be turned to concentricity with the shaft bearing seats.

The surface finish should be between 40 and 60 micro-inches (1.02 and 1.52 microns). No flat spots or high, low or loose segments should exist.

Commutators should have sufficient stock to ensure proper brush performance. Manufacturer’s limits should apply.

2.8.2 Undercutting and Beveling

The mica should be undercut, or left flush, as re-quired by the application. When undercut, the mica should be removed along the sides of the bar for at least the complete length up to the riser or dust groove and to a depth of approximately the width of the slot. Undercut areas should be free of foreign material and high mica.

Beveling may be required for those commutators that have rough segment edges resulting from work-hardening of the copper during the undercutting process.

2.9 BRUSHHOLDERS

Brushholders should be clean and free of any de-bris, oil, or dirt. Movable brushholder parts should be free working. The brush fit in the brushholder box should be inspected for excessive clearance, and worn brushholders should be replaced. Clearances should be as specified in Table 2-12.

Brush stud insulation should be free of cracks and should not be charred or have missing components.

In the final assembly of the machine, brushhold ers should be adjusted for clearance to the commuta-tor or slip rings of 0.060 inch (1.5 mm) to 0.125 inch (3 mm), depending on the size of the unit. Manufac-turer’s specifications should apply.

For commutator machines, it should be verified that the brushholders align the brushes with the commutator bars and maintain equal circumferen-tial spacing between brushes.

Spring pressure should be measured and adjusted to a range recommended by the original equipment manufacturer or the brush manufacturer for the specific application and brush type.

Brushholders and jumpers should be high-poten-tial tested to the machine frame at the test voltage specified for the corresponding winding circuit (see Subsection 4.4).

2.10 BRUSHES

Brush shunts should be tight in the brush and connections to the holder should be clean and tight and maintain clearance to other components.

The face of the brush should be seated, or con-toured, to make full contact with the commutator surface or slip rings. The brush fit in the brushholder box should be inspected for side clearance (see Table 2-12) and for excessively worn brushes. Brushes worn beyond useful length should be replaced.

Brushes in the same circuit of a machine should be of the same grade unless otherwise specified by the original equipment manufacturer. For DC ma-chines, brushes should be the size and grade to give successful commutation in normal service.

2.11 BRUSH SETTING FOR DC

MACHINES

In the final assembly, the brush rigging should be positioned so that the brushes are set for brush neu-tral, with brush position clearly marked. Accepted methods of determining this position vary widely, and no single standard procedure applies.

Note: In an assembled DC machine, each brush must contact at least two commutator bars at a time. Then, the brush short-circuits the armature coil connected to these bars. The brushes are consid-ered to be set for brush neutral when the armature coils shorted by the brushes are midway between main poles.

2.12 AIR GAP OF MACHINES

The air gap of the machine should be uniform

(within plus or minus 10% of the average), or to original manufacturer’s specifications.

In a DC machine, the air gaps of the main poles should be uniform, and the air gaps of the interpoles should be uniform.

Section 2, Page 2

Section 2, Page 3

2.13 ACCESSORIES

2.13.1 Capacitors

Capacitors should be tested for rated capacitance and subjected to a high-potential test (see Paragraph 4.4). Capacitors should be replaced if damaged.

2.13.2 Starting Components and Switches

Short circuit devices, centrifugal mechanisms, switches, and starting relays should be verified for electrical and mechanical operation at correct speed and voltage. These items should be replaced if damaged.

2.13.3 Terminal Boards

Terminal boards should be replaced if damaged, with components of the same ampacity and tempera-ture rating of the original components.

2.13.4 Space Heaters

Space heaters should be tested at operating volt-age for rated current or power and subjected to a high-potential test (see Paragraph 4.4). They should be replaced if damaged.

2.13.5 Temperature Sensors

Bearing and winding sensors or protectors should be identical with or equivalent to the original devices in electrical and thermal characteristics.

Table 2-2. SHAFT EXTENSION DIAMETER TOLERANCES

IEC MACHINES

DIMENSIONS IN MILLIMETERS EQUIVALENT DIMENSIONS IN INCHES

Tolerance Designation

Nominal Shaft Diameter Tolerance Shaft Diameter Tolerance

Over Up To Over Up To j6* 6 10 +0.007 -0.002 0.236 0.394 +0.0003 -0.0001 j6* 10 18 +0.008 -0.003 0.394 0.709 +0.0003 -0.0001 j6* 18 30 +0.009 -0.004 0.709 1.181 +0.0004 -0.0002 k6 30 50 +0.018 +0.002 1.181 1.969 +0.0007 +0.0001 m6 50 80 +0.030 +0.011 1.969 3.150 +0.0012 +0.0004 m6 80 120 +0.035 +0.013 3.150 4.724 +0.0014 +0.0005 m6 120 180 +0.040 +0.015 4.724 7.087 +0.0016 +0.0006 m6 180 250 +0.046 +0.017 7.087 9.843 +0.0018 +0.0007 m6 250 315 +0.052 +0.020 9.843 12.402 +0.0020 +0.0008 m6 315 400 +0.057 +0.021 12.402 15.748 +0.0022 +0.0008 m6 400 500 +0.063 +0.023 15.748 19.685 +0.0025 +0.0009 m6 500 630 +0.070 +0.026 19.685 24.803 +0.0028 +0.0010

*In some countries the k6 tolerance is used instead of j6.

Reference: IEC Stds. 60072-1, C.1.4. Dimensions shown in inches are rounded off.

Table 2-1. SHAFT EXTENSION DIAMETER TOLERANCES

NEMA MACHINES

DIMENSIONS IN INCHES EQUIVALENT DIMENSIONS IN MILLIMETERS

Shaft Diameter Tolerance Shaft Diameter Tolerance

0.1875 to 1.5000, incl. +0.000 -0.0005 4.76 to 38.1, incl. +0.000 -0.013 Over 1.5000 to 6.500, incl. +0.000 -0.001 Over 38.1 to 165.1, incl. +0.000 -0.025

Reference: NEMA Stds. MG 1, 4.9.1. Dimensions shown in millimeters are rounded off.

Table 2-3. PERMISSIBLE SHAFT EXTENSION RUNOUT

NEMA MACHINES

DIMENSIONS IN INCHES EQUIVALENT DIMENSIONS IN MILLIMETERS

Shaft Diameter Shaft Runout* Shaft Diameter Shaft Runout*

0.1875 to 1.625 incl. 0.002 4.76 to 41.3, incl. 0.051 Over 1.625 to 6.500, incl. 0.003 Over 41.3 to 165.1, incl 0.076

*Maximum permissible change in indicator reading when measured at the end of the shaft extension.

Note: The permissible shaft runout tolerance has not been established where the shaft extension length ex-ceeds the NEMA standard. However, runouts for shafts longer than standard are usually greater than those indicated above.

Reference: NEMA Stds. MG 1, 4.9.7. Dimensions shown in millimeters are rounded off.

Section 2, Page 4

Table 2-6. SHAFT EXTENSION KEYSEAT

(KEYWAY) WIDTH TOLERANCES

IEC MACHINES

DIMENSIONS IN MILLIMETERS EQUIVALENT DIMENSIONS IN INCHES

Nominal Width of Keyseat (Keyway) Tolerance*

Width of Keyseat (Keyway) Tolerance*

Over Up To Over Up To 2 up to 3 -0.004 -0.029 0.078 0.118 -0.0002 -0.0011

3 6 0 -0.030 0.118 0.236 0 -0.0012 6 10 0 -0.036 0.236 0.394 0 -0.0014

10 18 0 -0.043 0.394 0.709 0 -0.0017 18 30 0 -0.052 0.709 1.181 0 -0.0020 30 50 0 -0.062 1.181 1.969 0 -0.0024 50 80 0 -0.074 1.969 3.150 0 -0.0029 80 100 0 -0.087 3.150 3.937 0 -0.0034

*Normal keys, Tolerance N9.

Reference: IEC Stds. 60072-1, C.1.5. Dimensions shown in inches are rounded off.

Table 2-4. PERMISSIBLE SHAFT EXTENSION RUNOUT

IEC MACHINES

DIMENSIONS IN MILLIMETERS EQUIVALENT DIMENSIONS IN INCHES

Nominal

Shaft Diameter Shaft

Runout* Shaft Diameter Shaft Runout*

Over Up To Over Up To 6 10 0.030 0.236 0.394 0.001

10 18 0.035 0.394 0.709 0.001 18 30 0.040 0.709 1.181 0.002 30 50 0.050 1.181 1.969 0.002 50 80 0.060 1.969 3.150 0.002 80 120 0.070 3.150 4.724 0.003

120 180 0.080 4.724 7.087 0.003 180 250 0.090 7.087 9.843 0.004 250 315 0.100 9.843 12.402 0.004 315 400 0.110 12.402 15.748 0.004 400 500 0.125 15.748 19.685 0.005 500 630 0.140 19.685 24.803 0.006

This table applies to rigid foot-mounted and flange-mounted machines.

* Maximum permissible change in indicator reading when measured midway along the shaft extension length.

Reference: IEC Stds. 60072-1, C.1.6. Dimensions shown in inches are rounded off.

Table 2-5. SHAFT EXTENSION KEYSEAT WIDTH TOLERANCES

NEMA MACHINES

DIMENSIONS IN INCHES EQUIVALENT DIMENSIONS IN MILLIMETERS

Width of Keyseat Tolerance Width of Keyseat Tolerance

0.188 to 0.750, incl. +0.002 -0.000 4.78 to 19.1, incl. +0.051 -0.000 Over 0.750 to 1.500, incl. +0.003 -0.000 Over 19.1 to 38.1, incl. +0.076 -0.000

Reference: NEMA Stds. MG 1, 4.9.2. Dimensions shown in millimeters are rounded off.

Section 2, Page 5

Table 2-8. MOUNTING SURFACE TOLERANCES, ECCENTRICITY AND FACE RUNOUT

NEMA TYPE C FACE-MOUNTING MOTORS AND

TYPE D FLANGE-MOUNTING MOTORS

DIMENSIONS IN INCHES EQUIVALENT DIMENSIONS IN MILLIMETERS

Rabbet

Diameter Tolerance on

Diameter Eccentricity & Face Runout*

Rabbet Diameter

Tolerance on Diameter

Eccentricity & Face Runout*

Less than 12 +0.000 -0.003 0.004 Less than 304.8 +0.000 -0.076 0.102 12 to 24 +0.000 -0.005 0.007 304.8 to 609.6 +0.000 -0.127 0.178

Over 24 to 40 +0.000 -0.007 0.009 Over 609.6 to 1016 +0.000 -0.178 0.229 *Maximum permissible change in indicator reading.

Reference: NEMA Stds. MG 1, 4.12, Table 4-5. Dimensions shown in millimeters are rounded off.

Table 2-7. LABYRINTH SEAL

DIAMETRAL CLEARANCE GUIDE

DIMENSIONS IN INCHES

Shaft Diameter*

3000 to 3600 rpm Diametral

Clearance** Shaft Diameter*

1800 rpm or lower Diametral

Clearance** From Up To (+.002”/-.000”) From Up To (+.002”/-.000”)

3.000 3.500 0.009 3.000 3.500 0.012

3.500 4.000 0.010 3.500 4.000 0.014

4.000 4.500 0.012 4.000 4.500 0.016

4.500 5.000 0.014 4.500 5.000 0.018

5.000 5.500 0.015 5.000 5.500 0.020

5.500 6.000 0.017 5.500 6.000 0.022

6.000 6.500 0.018 6.000 6.500 0.024

6.500 7.000 0.020 6.500 7.000 0.026

7.000 7.500 0.021 7.000 7.500 0.028

EQUIVALENT DIMENSIONS IN MILLIMETERS

Shaft Diameter*

3000 to 3600 rpm Diametral

Clearance** Shaft Diameter*

1800 rpm or lower Diametral

Clearance** From Up To (+.050mm/-.000mm) From Up To (+.050mm/-.000mm)

76 89 .230 76 89 .305 89 102 .255 89 102 .355

102 114 .305 102 114 .405 114 127 .355 114 127 .455 127 140 .380 127 140 .510 140 152 .430 140 152 .560 152 165 .455 152 165 .610 165 178 .510 165 178 .660 178 191 .535 178 191 .710

Speeds given are synchronous speeds corresponding to the applicable line frequency and winding poles. Dimensions shown in millimeters are rounded off.

The above table is to be used for horizontal machines with bronze/brass labyrinth seals, absent specific clearance recommendations from the manufacturer. Galling materials, such as cast-iron, may require greater clearance. Vertical machines may require less clearance. Labyrinth seal clearance must always be greater than the bearing clearance. A general rule of thumb suggests labyrinth seal clearance should be 0.002” - 0.004” (.050 - .100 mm) greater than the sleeve bearing clearance.

* The shaft diameter is the diameter at the seal fit; and “up to” means “up to but not including.”

** The diametral clearance is the clearance for the applicable range of shaft diameter.

Section 2, Page 6

Table 2-9. MOUNTING SURFACE TOLERANCES, ECCENTRICITY AND FACE RUNOUT

NEMA TYPE P FLANGE-MOUNTING MOTORS

DIMENSIONS IN INCHES EQUIVALENT DIMENSIONS IN MILLIMETERS

Rabbet

Diameter Tolerance on

Diameter Eccentricity & Face Runout*

Rabbet Diameter

Tolerance on Diameter

Eccentricity & Face Runout*

Less than 12 +0.003 -0.000 0.004 Less than 304.8 +0.076 -0.000 0.102 12 to 24 +0.005 -0.000 0.007 304.8 to 609.6 +0.127 -0.000 0.178

Over 24 to 40 +0.007 -0.000 0.009 Over 609.6 to 1016 +0.178 -0.000 0.229 Over 40 to 60 +0.010 -0.000 0.012 Over 1016 to 1524 +0.254 -0.000 0.305

*Maximum permissible change in indicator reading.

Reference: NEMA Stds. MG 1, 4.13, Table 4-6. Dimensions shown in millimeters are rounded off.

Table 2-10. MOUNTING RABBET (SPIGOT)

DIAMETER TOLERANCES

IEC FLANGE-MOUNTED MACHINES

DIMENSIONS IN MILLIMETERS EQUIVALENT DIMENSIONS IN INCHES

Tolerance Designation

Nominal Rabbet (Spigot)

Diameter Tolerance Rabbet (Spigot) Diameter Tolerance

Over Up To Over Up To j6 30 50 +0.011 -0.005 1.181 1.969 +0.0004 -0.0002 j6 50 80 +0.012 -0.007 1.969 3.150 +0.0005 -0.0003 j6 80 120 +0.013 -0.009 3.150 4.724 +0.0005 -0.0004 j6 120 180 +0.014 -0.011 4.724 7.087 +0.0006 -0.0004 j6 180 250 +0.016 -0.013 7.087 9.843 +0.0006 -0.0005 h6 250 315 0 -0.032 9.843 12.402 0 -0.0013 h6 315 400 0 -0.036 12.402 15.748 0 -0.0014 h6 400 500 0 -0.040 15.748 19.685 0 -0.0016 h6 500 630 0 -0.044 19.685 24.803 0 -0.0017 h6 630 800 0 -0.050 24.803 31.496 0 -0.0020 h6 800 1000 0 -0.056 31.496 39.370 0 -0.0022 h6 1000 1250 0 -0.066 39.370 49.213 0 -0.0026 h6 1250 1600 0 -0.078 49.231 62.992 0 -0.0031 h6 1600 2000 0 -0.092 62.992 78.740 0 -0.0036 h6 2000 2200 0 -0.110 78.740 86.614 0 -0.0043

Note: This table applies to machines with FF, FT and FI mounting flanges.

Reference: IEC Stds. 60072-1, C.1.7. Dimensions shown in inches are rounded off.

Section 2, Page 7

Table 2-11. MOUNTING SURFACE ECCENTRICITY AND FACE RUNOUT

IEC FLANGE-MOUNTED MACHINES

DIMENSIONS IN MILLIMETERS EQUIVALENT DIMENSIONS IN INCHES

Nominal Rabbet

(Spigot) Diameter Eccentricity & Face Runout*

Rabbet (Spigot) Diameter Eccentricity &

Face Runout*Over Up To Over Up To 40 up to 100 0.080 1.575 3.937 0.003

100 230 0.100 3.937 9.055 0.004 230 450 0.125 9.055 17.717 0.005 450 800 0.160 17.717 31.496 0.006 800 1250 0.200 31.496 49.213 0.008

1250 2000 0.250 49.213 78.740 0.010 2000 2240 0.315 78.740 88.189 0.012

Note: This table applies to machines with FF, FT and FI mounting flanges.

*Maximum permissible change in indicator reading.

Reference: IEC Stds. 60072-1, C.7. Dimensions shown in inches are rounded off.

Table 2-12. BRUSH-TO-

BRUSHHOLDER CLEARANCE

DIMENSIONS IN MILLIMETERS EQUIVALENT DIMENSIONS IN INCHES

Nominal Brush Dimensions Width and Thickness

Clearance Nominal Brush

Dimensions Width and Thickness

Clearance Max. Min. Max. Min.

1.6 2.5

0.144 0.044 1/16 0.0056 0.00175

3.2 0.158 0.050 1/8 0.0062 0.0020

0.178 0.050 3/16 0.0070 0.0020

6.3

0.193 0.055 1/4 5/16 3/8

0.0076 0.0022

12.5

0.232 0.072 7/16 1/2 5/8

0.0091 0.0028

0.254 0.080 3/4 7/8

0.0100 0.0032

0.300 0.100 1-1/4 1-1/2

0.0118 0.0039

0.330 0.110 1-3/4

0.0130 0.0043

Reference: IEC Stds. 60136, Table I. Dimensions shown in inches are rounded off.

To avoid confusion between dimensions in millimeters and in inches, brushes and brushholders may have markings as follows: metric dimensions ❒; inch dimensions ∆.

NOTE: Replacement of a brush made to inch dimensions with a brush made to mil-limeter dimensions (or vice versa) might cause problems because of an improper fit in the brushholder.

Section 2, Page 8 Ta b le

-1

3.

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Section 2, Page 9

Ta b le

-1 4.

C Y

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. A da pt ed fr om

A

BM

A St d.

, T ab le s

1, , 3 a nd

. T he a bo ve s ha ft

(in te rfe re nc e) fi ts a nd h ou si ng

(c le ar an ce ) fi ts a re p ra ct ic al fo r m os t s ta nd ar d el ec tri c m ot or a pp lic at io ns . W he re w id er to le ra nc es

(h ou si ng fi ts

) a re p er m is si bl e, u se to le ra nc e cl as s h7 in st ea d of h

6.

S om e ap pl ic at io ns s uc h as h ol lo w s ha ft m ot or s, s pi nd le m ot or s an d vi br at or m ot or s re qu ire a d iff er en t t ol er an ce c la ss th an s ho w n in th e ta bl e.

Section 3 Rewinding

3.1 INSPECTION

3.1.1 Core Laminations

Core testing of stators and armatures should be performed before burnout or other equivalent process and after winding removal, and the results should be compared. Stator and armature cores should be tested for hot spots and losses (see Para-graph 4.2.6).

3.1.2 Thermal Protectors or Sensors

Thermostats, resistance temperature detectors (RTDs), thermocouples and thermistors should be checked for electrical and physical defects.

3.2 REWIND SPECIFICATION

The winding should maintain the same electrical characteristics as the original. Winding data should be reviewed for accuracy.

3.3 STRIPPING OF WINDINGS

Core temperature should be controlled to avoid degradation of the interlaminar insulation and distortion of any parts. The temperature should not exceed 700°F (370°C) for organic and 750°F (400°C) for inorganic coreplate. If a burnoff oven is used, the oven should have a water suppression system. Parts should be oriented and supported in the oven so as to avoid distortion of the parts. After the winding is removed, the core slots should be inspected to ensure they are free of sharp edges and foreign materials.

3.4 INSULATION SYSTEM

The entire insulation system, materials, and meth-ods of application should be equal to or better than that used by the original machine manufacturer.

All components of the insulation system must be compatible with each other with respect to electrical, mechanical, and thermal characteristics. The insu-lation system should withstand the high-potential tests described in Subsection 4.4 and the normal operation of the machine.

3.5 CONDUCTORS

The current-carrying capacity, insulation, and mechanical qualities of the conductors should be suitable for the environment in which the machine is to operate. If the conductor material is changed, it should be equal to or better than the original mate-rial in all aspects of performance and application.

3.6 STATOR, ROTOR, AND

ARMATURE COILS

Coil extensions should not be longer than the originals. The wire cross-sectional area should be at least equal to the original manufacturer’s speci-fications.

3.6.1 Random-Wound Coils

Coils should be wound and inserted in the core slots with a minimum of crossed conductors. Care should be taken not to damage the insulation or conductors. Coils should be wedged with full-length top sticks to hold them securely in the slots. Inter-phase insulation should be used (where applicable).

3.6.2 Form-Wound Coils

The fabricating of coil loops and the forming of these loops into the coil shape should be accom-plished without damage to the conductor insulation.

Each layer of coil insulation should be uniformly and tightly applied to minimize stress points and air voids.

Coils should be placed in the core slots without damaging the coil insulation. Coils should tightly fit slots. Coils should be wedged to hold them securely in the slots. Surge rings or similar supports should be secured to the coils and the coils laced to one another as necessary to minimize coil distortion and movement.

3.7 FIELD COILS

3.7.1 Stationary Coils

Varnish treatment of shunt, series and interpole coils is acceptable for coils originally manufactured by this method; otherwise, vacuum pressure im-pregnation may be utilized when a complete bond between insulation and conductors can be ensured.

The insulation of the outer coil layer should be sufficient to withstand surges or inductive voltage spikes.

3.7.2 Rotating Coils

High rigidity and bonding of all the components is required to withstand centrifugal forces. A high bond strength thixotropic resin should be used.

Coils and pole pieces should be securely wedged and braced when installed.

3.8 SQUIRREL CAGE AND

AMORTISSEUR WINDINGS

Bars for squirrel cage and amortisseur wind-ings should fit tightly in the core slots. End rings should be secured to the bars by welding or braz-ing, as appropriate for materials used. The winding should maintain the same electrical, thermal and mechanical characteristics as the original unless

Section 3, Page 1 redesigned by agreement with, or at the instruction of, the customer.

For balancing, see Subsection 2.6.

3.9 THERMAL PROTECTORS OR

SENSORS

Thermostats, resistance temperature detectors (RTDs), thermocouples and thermistors should be identical with or equivalent to the original devices in electrical and thermal characteristics and placed at the same locations in the winding. Thermal protec-tors or sensors should be removed or omitted only with customer consent.

3.10 SHAPING AND LACING OF

STATOR WINDINGS

End windings should be shaped and laced as needed to provide the necessary clearance to the rotor, stator, frame, bearing housings, air deflectors and frame hardware. On machines with metal surge rings (coil supports), the rings should be suitably insulated, accurately fitted and laced to the coils to ensure adequate support for the winding. The wind-ing should maintain the same electrical, thermal and mechanical characteristics as the original unless redesigned by agreement with, or at the instruction of, the customer.

Restrictions to air flow should be avoided.

3.11 COIL CONNECTIONS

3.11.1 Making Connections

Connections which are made by crimping, solder-ing, brazing, or welding should use materials that have adequate conductivity and are mechanically strong enough to withstand the normal operating conditions. Materials such as solder paste, fluxes, inhibitors and compounds, where employed, should be neutralized after using. These materials should be suitable for the intended use and of a type that will not adversely affect the conductors. Soldered joints should not be used in place of brazed or welded joints.

Connections and splices should be so constructed as to have resistance no greater than that of the conductors.

3.11.2 Insulating Connections

Connections should be adequately insulated to withstand the temperature and voltage ratings of the machine and be mechanically adequate to withstand normal operation. Connections and leads should be laced, tied, or otherwise securely fastened to prevent movement.

The insulation should be applied so as to allow the varnish/resin to penetrate.

3.12 WEDGES

Wedges for stators, armatures and rotors should have adequate mechanical strength and thermal rating to withstand normal operation of the machine.

Magnetic wedges should be replaced with equivalent magnetic wedges

Wedges should fit tightly in the slots.

3.13 BANDING OF ROTORS AND

ARMATURES

Resin-filled glass banding tape may be applied directly to the winding. It should be applied at the manufacturer’s recommended tension and method of curing. The banding should be of sufficient thick-ness and width to restrain the coils during normal operation.

When wire banding is used, it should be applied to the winding over banding insulation. The band-ing should match the original in location, material (magnetic or non-magnetic), wire size and number of turns. The wire should be applied with sufficient tension to hold the coils in place without distorting them.

Caution: Replacing wire banding with resin-filled glass banding may change the magnetic circuit configuration, affecting commutation and thermal rating of the winding. Similar effects may result from replacing glass banding with wire banding.

3.14 IMPREGNATION OF WINDINGS

Windings of rewound machines should be pre-heated, varnish/resin treated and cured using a method of application and a material of sufficient thermal rating to withstand the normal operation of the machine. The treatment should be compatible with the entire insulation system and suitable for the environment in which the machine is to operate.

Section 3, Page 2

Section 4 Testing results of tests on similar machines. No standard interpretation of results has been established (Ref-erence: IEEE Stds. 432, Sec. 8.1).

4.2.4 Turn-To-Turn Test

Accepted methods of testing turn-to-turn insu-lation vary widely. No single standard procedure applies, although several standards address the subject (IEEE Stds. 432, 522, and 792; and NEMA Stds. MG 1, 12.5).

4.2.5 Winding Surge Test

The winding surge test is most often applied to complete new or used windings using a test voltage of twice the circuit rating plus 1000 volts.

4.2.6 Interlaminar Insulation Test

Testing of alternating current cores should be performed with a core loss tester or by the loop test method; or by an EL CID test. The magnetic flux level for the after winding removal test should be within 5% of the before winding removal level. Any increase in losses or hot spots should be investigated;

and damaged laminations should be repaired or replaced.

4.2.7 Bearing Insulation Test

Insulation resistance (IR) tests should be 1 megohm or greater for motors operating from a sinusoidal or direct current power supply. Bearing

4.1 SAFETY CONSIDERATIONS

See Appendix for safety considerations.

4.2 INSULATION CONDITION

INSPECTION AND TESTS

Tests should be performed to indicate the suit-ability of the insulation for continued operation.

Insulation resistance (IR) tests should be performed with acceptable results before the high-potential tests. Other tests, indicated below, may also be ap-plied. All test results should be retained. Trends in results are often better condition indicators than the absolute values.

4.2.1 Insulation Resistance Test

Test voltage should be applied for one minute.

(Reference: IEEE Stds. 43, Sec. 5.4 and 12.2.)

GUIDELINES FOR DC

VOLTAGES TO BE APPLIED DURING

INSULATION RESISTANCE TEST

Winding Rated Voltage (V)a

Insulation Resistance Test Direct Voltage (V)

<1000 500 1000 - 2500 500 - 1000 2501 - 5000 1000 - 2500

5001 - 12,000 2500 - 5000 >12,000 5000 - 10,000 a Rated line-to-line voltage for three-phase AC machines, line-to-ground (earth) for single-phase machines, and rated direct voltage for DC machines or field windings.

Reference: IEEE Stds. 43, Table 1.

4.2.2 Polarization Index (P.I.) Test

The polarization index (P.I.) test should be per-formed at the same voltage as the test in Paragraph

4.2.1 for ten minutes. The recommended minimum value of polarization index for windings rated Class B and higher is 2.0 (References: IEEE Stds. 43, Sec.

12.2; and IEEE Stds. 432, App. A2).

If the one minute insulation resistance is above 5000 megohms, the calculated polarization index (P.I.) may not be meaningful. In such cases, the P.I.

may be disregarded as a measure of winding condi-tion (Reference: IEEE 43, Sec. 12.2.2).

4.2.3 Insulation Power Factor Tests

Insulation power factor, dissipation factor, and tip-up tests may be performed on large machines.

Interpretation of results is by comparison with

Section 4, Page 1

RECOMMENDED MINIMUM INSULATION

RESISTANCE VALUES AT 40 C

(All Values in MΩ)

Minimum Insulation Resistance Test Specimen

IR1min = kV + 1 For most windings made before about 1970, all field windings, and others not described below.

IR1min = 100 For most DC armature and AC windings built after about 1970 (form-wound coils).

IR1min = 5 For most machines with random-wound stator coils and form-wound coils rated below 1 kV.

Notes:

1 IR1min is the recommended insulation resistance, in megohms, at 40°C of the entire machine winding.

2 kV is the rated machine terminal-to-terminal voltage, in rms kV.

Reference: IEEE Stds. 43, Table 3.

insulation systems used in variable frequency drive applications should be evaluated to provide adequate impedance for the given drive application. [Note:

There is no industry consensus on a minimum in-sulation resistance or impedance value for bearings used with variable frequency drives.]

4.2.8 Phase Balance Test

The phase balance test applies balanced reduced voltage 3-phase power to the stator and the current is measured and checked for balance.

4.2.9 Polarity Test

The polarity test applies direct current, usually to a single phase, and the magnetic polarity of the coil groups are checked.

4.2.10 Dummy Rotor Test

The dummy rotor test uses an artificial rotor such as a small rotor with a loose fit on a shaft. Reduced voltage 3-phase power is supplied to the stator and the rotor is moved circumferentially along the bore to check for continuous rotor rotation.

4.2.11 Impedance Test

The impedance test applies an AC voltage to the two leads of a coil and the voltage and current are measured. Using Ohm’s Law the impedance is calcu-lated. The impedance of the individual coils is then compared for relative equality among coils that are intended to have equal electromagnetic qualities.

4.3 RECOMMENDED WINDING TESTS

Windings should be tested to ensure that there are no grounds (earth faults), short circuits, open circuits, incorrect connections or high resistance connections.

4.3.1 Stator and Wound-Rotor Windings

The IR, winding surge and winding resistance tests should be performed. In addition one or more of the following tests may be performed:

(1) Phase-balance test.

(2) Polarity test.

(3) Artificial rotor (dummy rotor) test (low voltage energization).

(4) Polarization index test or dielectric absorption test.

(5) Insulation dissipation or power factor test.

(6) Turn-to-turn test.

(7) Partial discharge testing for inception and extinction voltage levels.

4.3.2 Squirrel Cage Windings

One or both of these tests should be performed:

(1) Growler test.

(2) Single-phase test.

4.3.3 Armature Windings

An insulation resistance test should be performed.

In addition, one or more of the following tests should be performed:

(1) Growler test.

(2) Winding surge test.

(3) Bar-to-bar resistance test.

4.3.4 Shunt, Series, Interpole, Compensating and Synchronous Rotor Windings

An insulation resistance test should be performed.

In addition, one or more of the following tests should be performed:

(1) Winding resistance test.

(2) Winding surge test.

(3) AC voltage drop test.

(4) Impedance test.

4.3.5 Interconnection of Windings

Shunt, series, interpole, compensating, and syn-chronous rotor windings should be tested to ensure that the polarities and connections are correct.

Terminal and lead markings should comply with Subsection 1.6.

4.4 HIGH-POTENTIAL TESTS

High-potential tests should be performed on wind-ings and certain accessories of electrical machines at a specified voltage. To avoid excessive stressing of the insulation, repeated application of the high-potential test voltage is not recommended.

Machines to be tested must be clean and dry.

Inspection and insulation resistance tests with acceptable results should be performed before the high-potential tests. Insulation resistance tests should be repeated at the completion of the high-potential tests.

When a high-potential test is conducted on an as-sembled brushless exciter and synchronous machine field winding, the brushless circuit components (di-odes,…