Luse Coils Generator & Turbine Repair Serices

SERVING Industry SINCE 1923

And Our Partnership Team providing Inspection ,

Testing , & Repair of Generators, Turbines, & Stators

Generator Testing & Inspection

Generator Services

• Field Services

• Stator Services

• Testing & Inspections

• Hydraulic Integrity Test (HIT)

• Liquid-Cooled Clip Repairs

• High Voltage Bushings

• Reverse Engineering

Generator Field Services

Turnkey Rewinds

Technical Direction

Retaining Ring Change Outs Using Induction

Heating

Retaining Ring Machining & Insulation

Repairs of Elongation, Foreshortening & Top

Turn Isolation

Main Lead Manufacturing

Containment Facilities & Asbestos Abatement

Copper Dust Inspections

Bore Copper Inspection & Replacement

NDE of Wedges, Forging & Rings

Hydrogen Seal Inspection

Turnkey Collector Ring Services

Painting of Forgings

Application of Tagging Compounds

Turnkey Transportation

Generator Stator Services

Conventional and Liquid-Cooled Rewinds

Turnkey Disassembly & Assembly

New Stator Bars, Including Liquid-Cooled

Project Management & Technical Direction

Bar Insulation Repair

Repair of core iron

End Winding Redesign & Installation

Re-Wedging & Upgrades, Including TIL-

1197

Tagging Compounds for Core Monitoring

Installation of Flux Probes, Buss & Slot

Couplers

Installation of New RTDs

Electrical Testing & Inspection Services

AC & DC Hi Potential Test

AC Impedance Tests

Digital ELCID

Meggar

Boroscopic Inspections

Pole Balance Drop

Calculation of Polarity Indexes

DC Leakage

Wedge Surveys and Mapping

Resistance Testing of RTDs

Visual Inspections

Capacitance Mapping

Retaining Ring Inspections

H.I.T. Skids / Flush & Bake Skids

For Liquid Cooled Generators

Five Skids

Tools to Address TIL 1098

Fast Dry Out of Cooling System for

Elec. Testing

Prep For Vacuum & Pressure Decay

Tests

Flush & Bake Skids:

Flush Stator Cooling System & Bars

After Rewind

Cures Epoxies & Conforming

Materials

Reduces Bake Cycle Significantly

High Voltage Bushing Refurbishment

New or Refurbished High Voltage

Bushings :

Re-manufacture & rebuild nearly all

models

Refurbishment cost much less than new

bushings

Provides an opportunity to upgrade

bushing components

Faster turn-around than waiting for new

bushings

We maintain a finished inventory of

common bushings

Porcelain or composite insulators

Complete electrical testing

Turnkey installation

Rotor Testing & Inspection

Components of a Field

Collector Rings

Journal

Fan Ring

Retaining Ring

Body

Slot

Blocking

Coils

Coupling

Components of a Field Slot

Wedge

Creepage

Turns

Turn Insulation

Slot Armor

Sub Slot Armor

Typical Electrical Field Test on a Generator Rotor

Megohm Test (megger)

Winding Resistance Test

AC Impedance Test

Pole Balance Test

Visual Inspections

Field Testing

Megohm Test (megger)

Checks Ground Wall Insulation

Slot Liners

Creepage Blocks and Slot Bottom Covers

Retaining Ring Insulation

Terminal Stud Insulation

Bore Copper Tube

Collector Ring Sleeves

Field Winding Resistance Test

Measurement is converted to standard temperature specific to the

manufacturer

Field Winding Resistance Test

Typical Issues to Identify

Lower than Normal Resistance Means

Turn

to Turn Shorting is Present

Higher than Normal Resistance Could

Mean

a Few Different Things:

Cracked Conductor

Elongated Conductors

Bad Connection

Field Testing

AC Impedance Test

Checks for Turn to Turn Shorting

Rotor Acts as an Inductor when

Passing AC

Current Through the Windings

The Current Flow is “Choked” or

Restricted by

the Number of Turns Around the Iron

Core

(Rotor Body)

AC Impedance Test Set

Voltage is raised in 10V steps and current is measured at

each step.

Also, Impedance (Ohms) is calculated

Pole Balance Test

Only Performed if Access is Available to

the Pole to Pole Connector (or Very Close

By)

Usually Performed with AC

Voltage Applied as High as Practical--

Usually 100V

Voltage is Measured from Inboard Collector

Ring to the Pole Jumper and then from the

Field Testing

Field During Rewind

Bore Copper Assembly

Stator Testing

Stator (Armature) Testing

Winding Resistance Test

Megohm Test (megger)

DC Leakage Test

DC Hipot

RTD Resistance Test

RTD Megger Test

Winding Resistance Test

oMeasured with a Digital Low Resistance

Ohm

Meter (DLRO)

• Also Known as a “Bridge”, “Ductor”,

“Micro Ohm Meter”

Regardless of Name, All are a 4 Wire Kelvin

Bridge Device

Stator Field Testing

Stator Field Testing

Megohm Test (megger)

Checks Ground Wall Insulation

Taped Insulation on Bars/Coils

Porcelain or Epoxy Insulation on

Terminal and Stand-off Bushings

Hoses on Water or Oil Cooled

Machines

Stator Field Testing

Megohm Test (megger)

Usually Performed at 2500 V or 5000 V

for 10 Minutes

All Megger Tests are DC

Achieve a Final Megohm Reading and

Polarization Index (PI)

PI = R10 / R1

Stator Field Testing

Megohm Test (megger)

Reduced Creepage Paths (Distance to

Ground) Can Lead to Low Megohm

Readings

Dirty or Contaminated

Bushings/Terminals

Insulation Migration (Big Problem in

Certain Asphalt-Mica Machines)

Stator Field Testing

AEMC Electronic

Megohm Meter

Stator Field Testing

DC Leakage Test

A High Voltage Test of the Stator

Windings Used to Gain Quantitative

and Historical Data as to the

Condition of the Insulation

DC Tests in General are Sensitive

Indicators of the Presence of

Cracks, Fissures, Reduced

Creepage Paths, Moisture and Dirt

Stator Field Testing

DC Leakage Test

Consists of a Series of Insulation

Resistance Measurements Taken at

Increasing Voltage Steps on a

Scheduled Time Basis

A 10 Minute Preliminary Di-electric

Absorption Test Determines the

Absorption Ratio of the Insulation

(N number)

Stator Field Testing

DC Leakage

Test Underway

Stator Field Testing

DC Leakage Test

Sphere-Gap Voltmeter Is Used to

Verify Voltmeter and for Overvoltage

Protection

Sphere-Gap Voltmeter (Spheres) Are

Set to Arc Over at 10 to 15% Higher

Than Max Test Voltage

Set High Enough So That It Does Not

Add Significant Leakage Current

Stator Field Testing

80 KV DC Hipot, Isolation

Transformer and Sphere-Gap

Voltmeter

Stator Field Testing

DC High Potential Test (Hipot)

Final Suitability for Service Test

Substitute for AC Test, Which

Requires a Large and Expensive Piece

of Equipment

May or May Not Be Required by

Insurance Company

Stator Field Testing

DC High Potential Test (Hipot)

Often Times Is Performed as the

Last Step of a DC Leakage Test

Leakage Value Is Not Important

Since Extraneous Leakage Currents

Can Be Very High

Surface Tracking

Ionization of Air Near Terminals

Stator Field Testing

RTD Testing

Resistance Test

Resistance Is Measured

Between Each Leg (wire)

Excel Spread Sheets Calculates

Temperature

Checked to Insure That All

RTDs are Functional

Stator Field Testing

RTD Testing

Megger Test (Slot RTDs Only)

Resistance to Ground Is

Measured at 500 Volts

Checked to Insure That

RTDs are Not Capable of

Creating Circulating

Currents Which Could

Result In Localized Heating

and Back Feeds into the

Meters

Stator Photos

End Windings

and Core on

Large Water

Cooled

Generator

Stator Photos

Stand-Off

Insulator

Stator Photos

PTFE Hoses

on Water

Cooled Stator

Stator Photos

Tape

Separation on

Asphalt-Mica

Bar

Stator Photos

Typical GE RTD

Panel

Turbine-Generator Repair Facility

• 170, 000 Square Feet

• 90 Ton Crane Capacity

• Dedicated Blast Cleaning

• High Speed Balance Facility

(late 2013)

Reverse Engineering: Addressing Critical Needs

Reverse Engineering: Addressing Critical Needs

Focused on Stator Components (Free)

We Come to You

Experienced Staff

State-of-the-Art Equipment

Supported by In-house CAD & Engineering

Digital Material Composition Analysis

Quick Turn Around

THANK YOU FOR YOUR TIME !

QUESTIONS ?

YOUR INFORMATION REQUESTS RECEIVE OUR HIGHEST PRIORITY

Jim Ford

630.240.6381

jford@luse.com

John Provencher

708.363.3838

jprovencher@luse.com