2018 International Congress on Advances in Nuclear Power Plants

APPLICATION OF HIGHER HARMONICS
DIAGNOSTIC METHOD OF ELECTRIC POWER
SOURCE FOR RAPID DETECTION OF FAILEDELECTRIC MACHINE IN A REAL NUCLEAR
FACILITY BY FIELD WORKERS

Non Profit Organization
Symbio Community Forum,Kyoto, Japan

Hidekazu Yoshikawa, Professor Emeritus Kyoto University
Junya Nitta, Arcadia Systems, Inc.

Contents• What is higher harmonics diagnostic method?
• Target of Harmonics Diagnosis• Realizing diagnostic device for predictive maintenance• HAMOS Configuration for continuous remote monitoring• How diagnostic result is presented to maintainers• Concluding remarks
Non Profit Organization
Symbio Community
Forum, Kyoto, Japan

What is higher harmonics diagnostic method?
• The electric current
flows through theelectric equipment
basically as the form of
distorted wave which isthe composite of basic
wave and many higher
harmonic waves.

What is higher harmonics diagnostic method?
• Higher harmonics diagnosis• If the equipment is working
method will diagnose thenormally, higher harmonicstate of electric equipment bycomponents are not so large
examining what kinds ofin the electric current.
• But when some problem occurs higher harmonics with theirpercentage are contained insomewhere in parts andthe distorted wave.
modules, specific orders ofhigher harmonics will appear
and exhibit higher percentage
in the distorted wave.

What is higher harmonics diagnostic method?
However, in order to develop auseful diagnosis device with theuniversal applicability to many
types of electrical equipment, itis necessary to collect as many
data as possible from manyequipment.

As many as 37,200 data ofvarious electric equipment had
been collected by the firstinventor of this diagnostic
device who is called Hiroshi
Koh for more than ten years
from 1991 until 2002.

What is higher harmonics diagnostic method?
By applying principal component
analysis method of multivariate
analysis for the equipment
database, a sort of analyzed
table by “contribution ratio table”
had been introduced.

“Contribution ratio table” gives the listof the ratios of higher harmonics
contained in the distorted wave forthe various types of degradation invarious parts of various electric
device.
How the higher harmonics diagnosis
is conducted by using “Contributionratio table”? It will be explained by an
example case in the next three slides.

Degradation observed in bearing

Photo 1 Wear of ball bearing

Photo 2 Scratch of bearing caseComparison of abnormal bearing of the pumpwith normal one in contribution ratio table
Order of harmonics

2nd

3rd

4th

5th

Contribution index fromthe measured higher
harmonics content ratio(basic figure)

0.944

0.154

0.274

0.103

NormalbearingHarmonics
content ratio(%)

3.1

2.6

1.3

2.1

Contribution
index

0.32

0.269

0.130.216

Harmonics
content ratio
(%)

2.7

1.4

1.1

4

Contribution
index

0.675

0.35

0.275

0.5

Abnormalbearing(wear ofballbearing)Harmonics Diagnosis and Its Benefit
HAMOS

Contactless and Live State
Measurement by search coil at theControl Panel of the local machine.

Enables overall system diagnosis ofAbnormality and/or Deterioration forvarious parts of Motor, Load, andInverter-Electric Power Balance is diagnosed to see how the Loading
Mode between motor and load. (See next slide)-Optimum Motor Efficiency to Minimize Motor Loss can beobserved.

Target of Harmonics Diagnosis
HAMOS■Diagnosis Target

The primary target of Harmonics Diagnosis is Motor System and Inverter, the driving powersource for every industrial moving equipment. In addition, transformer, capacitor, generator,UPS, and power transmission/distribution cable can be diagnosed as well.

■Measurement Location and Diagnosable PartHarmonics measurement at Control Panel enables diagnosis of the overall system. It is likethe blood tests of human body

For motor system
Measured between U and V at Control Panel

For inverter-controlled system
Measured between U and V of Primary/Secondary circuits at Control Panel
Primary

SecondaryINV• Electrolyticcapacitors• Control PCBA
• Power devices• Driver PCBA

• Coupling• Rotating
shaft

MotorLoad• Bearing• Bearing atat load
opposite end ofendload• Bearingsof load••••

Installation
Insulation of windings
Housing
Air gap• Coupling• Rotating
shaft

MotorLoad• Bearing at• Bearing
opposite end ofat load
load
end

• Bearingsof loadRealizing diagnostic device for predictive maintenance
HAMOS

KS series【Basic features】
KS-1000・KS-2000

Non-contact type electric equipment diagnostic equipment◆Preventive maintenance and predictive
maintenance become possible
It can detect symptom of abnormal state, degradation state,and failure prediction.

◆Reduction of maintenance cost

You can measure without requiring any technical skills and so
you do not need high technical maintenance personnel.

◆Capable of live line diagnosis
You do not need to stop running the facilities to diagnose.
It is also possible to investigate deterioration symptoms(overheating, discharge phenomenon, leakage current etc.)that can only be measured in live state.

【Benefits of introduction】

KS series is a diagnostic instrument thatanalyzes, diagnoses, digitizes, and evaluates"harmonic" in the electric current .
This is the sensing technology to grasp anddiagnose the state of equipment and to predict
abnormality.

◆ Equipment plan after introduction It is possible to efficiently
collect data useful for prolonged life / update planning inconservation work.
◆ Periodic inspection can be made more efficient. Since it ispossible to carry out necessary measures surely within a limited
time, the quality of equipment maintenance can be improved.
◆ By collecting data, it is possible to cope with aging offacilities and for environmental change, so that preventive
maintenance of machine equipment, extension of equipment life
12and improvement of performance can be realized systematically.

HAMOS System Configuration for continuous remote monitoring●Harmonics Measurements for Max 1280 Systems Can Be Made
Harmonics Sensors
A/D Converters

Functions and Features

Mail reception
at abnormality
occurrence

１２８MPX

10CH Compensation
CircuitMails

The Remote MPX can be extended to max 200m long with daisy-chained LAN cables,
where one lane consists of 16 channels, and max 8 lanes of the Remote MPXs can beconnected. Max 10 units of the Remote MPX can be connected to the Compensation
Circuit, and therefore status monitoring of max 1280 channels of systems can be madeby the harmonics measurement tool.

nKS2000

How diagnostic result is presented by KS-3000 A• The results of diagnosing electric
device by KS-3000A is presented
to the maintenance workers by asheet of paper.
• The estimated degree ofdeterioration of the targetedelectric device, and both thetarget device and its attributes aswell as the various diagnostic
results are described in structured
table format as seen from the rightsheet.

How diagnostic result is presented• Various abnormal factors which would deteriorate motor,
load and inverter to comprise the target electric device aretaken into account in the KS-3000A.
• Based on the estimated abnormality/ deterioration inpercentage, the degree of deterioration for individual factors
are classified either as A(normal), B1, B2, B3 (light, middle
and noticeable deterioration, respectively), or C (worrisomedeterioration).
• The advice on how to cope with the problem are also givenin accordance with the degree of degradation together withthe list of plausible cause of deterioration. Also given is theremedial action to prevent failure.

Where this diagnostic method has been employed• This diagnostic method has been widely used for automobile companies, rail
way companies, electric power companies not only in Japan but also in Korea.
• As for the actual application for nuclear power plant in Japan, it was applied by
my advice for three PWR nuclear power stations owned by Kansai ElectricPower Company in 2009.

• It was confirmed that all the tested electric devices had exhibited no particulardeterioration symptoms. So, all tested devices were like brand new devices,and we at that time thought that this fact would prove the effectiveness of timebased preventive maintenance practice employed in the Japanese nuclear
power plants.
• At present, KS-3000A has been employed for diagnosing various electric
devices at the Japanese reprocessing plant in Rokkasho-mura, Aomori, Japan.

Concluding remarks
The higher harmonic diagnosis is adiagnostic method of electric
equipment based on statistical data
analysis method.
It measures the content of higher
harmonic in the electric current
flowing though the failed equipment,
while disassembling the failed
equipment to validate the cause ofanomaly.

The database of higher harmonics
content versus failed part is utilized
to reduce a sort of causeconsequence co-relationshipbetween the order pattern of
higher harmonic component andthe specific cause and parts ofdegradation in various electricdevice.

Concluding remarks
Since this diagnostic method
depends on experiential data
statistics, it has both merit anddrawback. The drawback lies in thatno theoretical explanation is given on
why specific order pattern of higher
harmonic appear when a certain
failure or degradation occur in aspecific part.

The limit of scant database can beovercome by a new wave of big data
science by using the present-day
Internet of thing (IoT) and cloudcomputing with artificial intelligent (AI).
This is the new challenge of thepresented higher harmonics diagnostic
technology, and it is going by the coauthor’s company which is supportedby Ministry of Economy andInternational Trading (MEXT) as a partof “smart energy system project.”Thank you very much for yourkind attention.
Any question and comments?