lcm 500 presentation_2

7/14/2019 LCM 500 Presentation_2

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LCM 500

LeakageCurrent

Monitor

Presented by

Michal Slodkiewiczwww.doble.no


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Overview of presentation

Motivation and background

IEC 60099-5 available diagnostic methods

Requirements

LCM 500 unit and attached accessories

Performing self-test of LCM 500 unit

Preparation database of surge arrester

Grounding of the LCM 500 unit

Deployment of LCM 500 accessories during measurement on-side

Risk assessment


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Motivation and background

The MOSA is a cheap and passive component, but protectingcrucial apparatus

Overlooked despite of severe consequences if it fails

MOSAs can age and fail due to a variety of reasons

May offer inadequate over voltage protection, especially ifthe rated voltage is selected to low.

Diagnostic indicator: Resistive leakage current increases withtime increasing risk of failure


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Why test Metal Oxide Surge Arresters?

Utilize the lifetime of the operating MOSAs.

Prevent arrester failures by replacing aged arresters

before breakdown.

Avoid disturbances and costly outages of the electric

power supply.

Reduce the risk for damages to other equipment, for

instance transformer bushings.

Increase the safety for the utility/maintenance staff.


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Mechanism for degradation of MOSA

Sealing defects

Discharging due to surface contamination

Overloading

Long term aging during normal service

Internal partial discharges


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Degradation of MOSA

One consequence of the degradation of the MOSA isan increase with time of the resistive component ofthe continuous leakage current

Increase in resistive leakage current will cause an

increase in power losses and hence increasedtemperature in ZnO-blocks

The resistive current may exceed a critical limitwhere the accumulated energy in the ZnO-blocksexceeds the energy capability of the arrester. Thearrester will then get thermally unstable and fail.


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An arrester failure may appear in different ways:

Arrester with porcelain housing may explode

The arrester can be causing an earth fault due to internalflashover

Aged or overloaded arresters may have reduced protectionagainst overvoltages, i.e. it is not protecting the apparatus

it is supposed to protect.

Degradation of MOSA


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Requirements for surveyed surge arrester

1. Metal Oxide Surge Arrester - MOSA

2. Separate grounding wire

3. Insulated base for each arrester


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Why use insulated base arresters and separate earth leads:

Gives complete control of arrester current leading to the ground

Allows an easy on-line in service condition assessment test of theMOSA. Without insulated base you have to take the arrester out ofservice for proper condition testing.

If a surge counter is present, the clip-on should be placed above thecounter to avoid circulating currents from the counter ground loop.

Requirements for surveyed surge arrester


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IEC 60099-5 Part 5 Selectionand Application Recommendation


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Method B2 is rankedto be the best fieldmethod for

evaluation of ageingand deterioration ofMOSA.

Properties of on-site leakage current measurements:

A HV-DC test iseffective but off lineand complex

IEC 60099-5:Available diagnostic methods


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If the MOSA is energized by a pure sinusoidal voltage

(fundamental frequency only), the capacitive leakage

current will show a fundamental component I1c only,

while the resistive leakage current will show both a

fundamental component and a 3rd harmonic

component (I3r) due to its nonlinear properties.

The resistive components are said to be generated

by the arrester itself (due to the not linear current-

voltage characteristic) and can therefore be used as

a measure for the arrester condition.

IEC 60099-5: Metal Oxide Surge Arresters


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IEC 60099-5: Metal Oxide Surge Arresters

If harmonics are present in the operating voltage, this will

generate a significant 3rd harmonic component in the capacitive

leakage current in the arrester.

This capacitive 3rd harmonic component will be added to the

3rd harmonic component resistive component and create a

measuring error.

The LCM 500 uses a compensation method where the capacitive

component generated by the operating voltage is eliminated.


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Typical Voltage - Current Characteristics

The resistive currentcomponent:

is typically 5-20% of the totalleakage current under normal

operating conditions

is a sensitive indicator ofchanges in the voltage-currentcharacteristic

depends on the voltage and

temperature


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Equivalent Circuit of ZnO -Varistors

It

Ic200-3000 A Ir

10-600AU

Ir=It-Ic


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Leakage Current Measurements

Measurement of the total leakage current example:

Itot increases with only 1,5%

when the resistive vector is

doubled

This small change in Itot is not

measurable at a mAmeter

I

U

Ic1= 100

Ic2=100

Usyst

Ir2=20

I2total = 102

Ir1=10

I1tot = 100,5

1

2


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Recalculation of leakage current

By using arrester system data and measuring the ambienttemperature and operating voltage at the same time as thecondition monitoring is performed, it is possible to recalculatethe leakage current data to a common reference of:

20 C and U/Ur=0.7

The resistive leakage current values will then beapproximately the same independent of the test conditions

by taking account of the ambient temperature and operatingvoltage, measurements performed under different conditions can

be directly compared, and the measured values will be a reliableindicator of the arrester condition.


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Influence of ambient temperature and system voltageon resistive leakage current.

Temperature andsystem voltage influence


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1. LCM500 unit2. Current Probe

3. Field Probe

4. 12V DC cable

5. Field Rod adapter6. Power supply cable

7. Antenna

8. Grounding cable

9. Current loop wire

10.USB A+B cabel

11.Field test cable

www.doble.no

LCM 500-Leakage Current Monitor

2

14

3

8

76

911

10

5


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LCM 500-Leakage Current Monitor

Optional Accessory

Field Probe Rod delivered in separate transportcase. Rod is divided on 3 pieces for 1m each piece.

Cannot be used as a Hot Stick!


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Mains powersupply

Light diodes

LCD displayFour pushbuttons

Turning knob

External DCpower sypply

Power switch

Antenna input

Self test Communication ports

Select button

LCM 500 Front Panel


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LCM 500 Self-test outputs

FIELD

Simulated field probe signal to be

connected by coaxial cable (type RG58)

V.TRSF

Simulated voltage transformer signal to

be connected to the voltage transformer

adapter (optional accessory)

CURRENT

By connecting an electrical wire betweenthe two black connectors, a current loop

simulating total arrester leakage current

is created

Self-test outputs - perform function test of internal system


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LCM 500 Communication Ports

USB, RS232, Ethernet

By connecting data cables to one of above ports, the instrument cancommunicate with a PC using the enclosed Windows based data

management software LCMViewer.


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2-Clip-on current transformer CCT500:Measures the total current in thegrounding cable of surge arrester.

1-Field probe FP500 (antenna):Measures the capacitive currentfrom the electric field surroundingthe arrestor.

1

2

LCM 500 Wireless probes


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Performing self-test of LCM 500Circuit diagram


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MeasurementSystemTest

Teast:verifysystemSimul.:generatetestsignals

TestSimul. Main

LeakageCurrentMonitorLCM500

MeasSetupDbaseTest


Connect arrester and

antenna test signalsto probe before startStart Main

Performing self-test of LCM 500


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LCM500


Succeeded

Start Main

LCM500MeasurementSystem

TestFailedCONTACT

MANUFACTURERMeasured:Ir:205+/-8AIt:332+/-5A

Measurementin

progress

AquisitionstartedPLEASEWAIT!

>



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TROUBLE SHOOTING:

- Be sure that all connectionsbetween field test cablecrocodile clips are fastenproperly to Field Probe

- Observe that current loop is not invicinity or not around antenna


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Preparation of surge arrester inLCMViewer

i f i


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If you dont know therated voltage, thesoftware will recommend

a proper value based onsystem voltage andarrester type.

Define database of yoursurge arrester andtransfer this to the LCM500, use Add to LCMQueue button. Softwareautomatically will moveyou to Instrumenttab.


i f i


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Use Send Data to LCM

button in order send

data to LCM 500

instrument.


G tti ti


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1. Choose correct

ComPort for LCM 500

instrument.2. Use Test button to

check status of your

connection in Log

area.

Go to Instrument=>Setup, Logtab

Getting connectionbetween PC and LCM500


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Grounding of the LCM 500

The LCM 500 can be grounding in two ways:1.In laboratory testing or during charging battery by using

the power supply cable. Power supply plug has to be

connected to the local earth.

2.During field measurements grounding cable has to be

connected to local earth system in the substation.


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Grounding of the LCM 500


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Deployment of LCM 500 accessories

1. Gapless MOSA2. Insulated base

3. Grounding wire

4. Clip-on CT500

5. Counter

6. Field probe FP500

7. Arrester pedestal

8. Field Probe Rod9. LCM 500 unit

The Field Probe shouldNEVER exceed this limit

1

5

2

7

3

98

4


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Deployment of LCM 500 accessories


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LCM 500 Set-up Mode From Main Menu

LeakageCurrentMonitor

LCM500MeasSetupDbaseTest


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LCM 500 Set-up Mode From Main Menu

Language: only English.

Dump mode: ON is for use incontinuous measurements. Themeasurements will be dumpedcontinuously to the serial port. Whena PC with proper software is

connected the measurements can bedownloaded.

Time: battery backed real-time clock.

Backlight: time in sec. the light in the LCD display is turned on.

Baudrate: baudrate defines the data transfer speed duringcommunication with a PC and can be set to 9600 bit/sec. or 57600bit/sec.

Leanguage:English


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LCM 500 Measuring mode

LeakageCurrentMonitor

LCM500Meas SetupDbaseTest


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By pressing the MEAS button inthe main menu, the screenpresented on the left appears.

When database is transferred fromthe software, you will get access to

it in this menu.

If you press Setup in the above menu, you will enterthe measuring set-up mode

Station/Loc/Arrester:Nostationchosen


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LCM 500 Measuring set-up mode

Mode: In field test 3-phase mode should beset. 1-phase mode is for use in lab tests.

Temp: Choose between manual orautomatically setting of the temperature.

Line: The line-to-line operating voltage.

Choose between manual or automatic. Manualsetting is the most common. Automatic is forconnection to a PT combined with an adapter.

Transf:This ratio defines the voltage divider ratio of the voltage transformer

that can be connected for automatic voltage measurements. The ratio can be setfrom 1:1 up to 1:10000 in steps.

Mode:3-phase


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AutomeasurementStart :2011.02.10


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LCM 500 Perform a Measurement

If the measurement runs ok, the measuring result will be shown in

the LCD display like the example below.

Ircorr-total corrected resistive leakagecurrent with standard deviation(corrected value with regard to ambienttemperature and line voltage).

It-total leakage current

Ir-total uncorrected resistive leakagecurrent.

In addition the ambient temperature and the line voltage usedduring the measurement are displayed.

To save your measurement, press the Storebutton

90005STAA1PHR

Ircorr: 159AAnt.3rdharm.:0.8%It:587AIr: 89A24C 68kVRunStoreNewMain


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1. Click the Read

Measurements from

LCM to make the

transfer take place

2. Mark your SurgeArrester than use

Apply Measurements

(Auto only), all

performed

measurement will be

add to existing Surge

Arrester data.

Go to Instrument=>Measurementfrom Instrumenttab

Download the measurements


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Leakage Current Plot

The LCMViewer lets youcreate a graphical statisticalpresentation of your SurgeArrester measurements.

Easy way to compare

measurements for groupsof arressters.

Test Conditions

You can observe factor oftemperature, voltage andcontaining of 3th harmonicfrom taken measurements.

Structure and data analysis


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Arrester Test Reports

LCMViewer will generatean arrester report ineither Excel or pdf files.

You can select content ofinformation to be includedin the report.

You can use your companylogo.

Structure and data analysis


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Doble LCM - Your best choice!

You should choose:

A simple in-service method

Doble LCM takes less then 5 minutes perarrester, in service

Reliability method verified by independentsources

LCM method recommended by arrester IECstandard

Convincing references

Developed together with ABB!

Now in Siemens surge arrester monitoring catalog!

www.doble.no


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Risk Assessment


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Evaluation of the Arrester Condition

Based on the level and development of resistive leakage current

Ir over time: Trend analyses

In general look for increasing trend

Perform a baseline reading when the arrester is new. If Ir increases by 3-4 times(typically), it is indicating severe aging

Compare the value to maximum recommended leakage current values

given by arrester manufacturers ABB and Siemens provide max values

Compare Ir to arresters of same design and type

The three phases in a line or bay

All similar arresters in the grid

Test interval

In beginning once a year to get knowledge about trend. Later on each 3-5 year

It depends on age of the arresters, the regional lightning activity, thesituation of overvoltages, quality of the apparatus etc.


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Eliminating possible sources of error

Some steps to consider in the final evaluation:

1. If total current It and resistive current Ir are unrealistically high:

Check if the arrester base and the arrester grounding is inorder. Circulating currents??

2. If Ir is higher than expected:

Temporary heating of the ZnO-blocks inside?? Consider to re-test in approximately 1 day to confirm the value.

If surge counter is present: is the clip-on CT connected aboveit?

3. If high reading is stable and confirmed, consider monitoringcontinuously or proceed with step 4.

4. Contact the arrester manufacturer and consider replacing


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150 %

200 %

Years with measurements

100 %

1 2 3 4 5 6 7 8

Three differentarresters with almostthe same leakagecurrent

Which of them is themost dangerous?

Leakage current trendExcample

www.doble.no


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Years with measurements1 2 3 4 5 6 7 8

The same threearresters as above,with measurementsover 8 years.

Which of them ismost dangerous?

The yellow hasincreased its leakagecurrent from ~85% to95% in 8 years

The red one from

65% to 100% in 8years

The blue from 25% to95% the last 3 years!

Leakage current trendExcample

www doble no

150 %

200 %

100 %

lcm 500 presentation_2

Documents

test of lcm

no7142019 lcm

unit deployment of lcm

risk of failure7142019

risk assessment7142019

degradation of mosa7142019

presentation motivation

arrester failures