Ppm pre-preventive maintenance of electrical

7/29/2019 Ppm pre-preventive maintenance of electrical

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Title 36pt Times New Romanwith keywordin drive boxSubtitle 24pt Arial Narrow

Presenters NamePresenters TitleDate

keyword


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Topics

Definition of Preventive Maintenance (PM)

Reasons for the increased need of PM

Advantages of a PM system

Risks of running a PM system

When to use a PM system

The law of PM

Guide to a successful PM system

Execution process Conclusion

Readings


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What is Preventive Maintenance?

Preventive maintenance is a schedule of

planned maintenance actions aimed atthe prevention of breakdowns andfailures. The primary goal of preventivemaintenance is to prevent the failure of

equipment before it actually occurs. It isdesigned to preserve and enhanceequipment reliability by replacing worn

components before they actually fail.


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Reasons for the need of a PM system

Increased Automation

Business loss due to production delays

Production of a higher quality product

Just-in-time manufacturing

Need for a more organized, planned environment


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Advantages of a PM system

Reduced production downtime, resultingin fewer machine breakdowns.

Better conservation of assets and

increased life expectancy of assets,thereby eliminating prematurereplacement of machinery andequipment.

Timely, routine repairs circumvent fewerlarge-scale repairs.


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Continued -

Reduced cost of repairs by reducing secondary failures. When partsfail in service, they usually damage other parts.

Better quality products

Identification of equipment with excessive maintenance costs

Improved safety and quality conditions.


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Brainstorming Exercise

Are there any risks of running a PM system?

If there are risks when would it be a good time to use PM?


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Potential errors or damage

of a PM system

Damage to an adjacent equipment during a PM task.

Reintroducing equipment mortality by installing new parts ormaterials.

Damage due to an error in reinstalling equipment into its originallocation.


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When Does Preventive Maintenance Make

Sense

This is a logical choice that considers two conditions

- #1. The component in question has an increasing failure rate.

- #2. The overall cost of the preventive maintenance action must be less than theoverall cost of a corrective action.

If both of these conditions are met PM would make sense


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The Law of PM

Higher the value of the plant assets andequipment per square foot of plant, thegreater will be the return on a PM program.

E.g. - downtime in an automobile plant assembly line at one

time cost $10,000 per minute. Relating this to lost productiontime an automobile manufacturer reported that theestablishment of a PM program in their 16 assembly plantsreduced downtime from 300 hours per year to 25 hours peryear. With results such as this no well-managed plant can

afford not to develop a PM program.


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How to determine the optimum age of

replacement?


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How to determine the optimum age of

replacement?

A more technical approach.

Where:

R(t) = reliability at time t.

CP

= cost of planned replacement.

CU= cost of unplanned replacement CPUT(t) = The optimum replacement time


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The key for a successful PM system

Scheduling Should be automated to the maximum extentpossible

Execution Should be done before the actual break downoccurs.


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Execution

The Bath Tub Model Three

stages of new parts1. Infant morality stage

2. A fairly long run stage

3. Wear out stage

Traditional View according toBath Tub Model Replacecomponents just before theyentered wear out stage


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Execution

Traditional view says

Wear out stage = Increased rate of failure.

Point to Ponder

Since, wear out stage represents increased rate of failure,wouldnt it be plausible to execute the PM program at this stage?


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What really should PM focus on?

Cleaning Found through testing Lubrication and inspection

And correcting deficiencies

Predetermined parts replacement

should be minimal and done onlywhere statistical evidence clearlyindicates wear-out characteristics


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In the absence of data

Age exploration programs

Statistical analysis

Cost shouldnt be a primary factor in deciding against data collectionfor a PM


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Motivating Preventive Maintenance

Workers

Training programs most effective

Establish inspection and preventive maintenance as a recognized,

important part of the overall maintenance program.

Assign competent, responsible people to the preventive maintenanceprogram.


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Continued -

Follow-up to assure quality performance and to show everyone that managementdoes care.

Provide training in precision maintenance practices and training in the righttechniques and procedures for preventive maintenance on specific equipment.

Set high standards.

Publicize reduced costs with improved up-time and revenues, which are the resultof effective preventive maintenance


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Summary

PM is not difficult to achieve. It is an essential part for cost reduction

There is an element of risk involved in PM

Careful planning and execution will reduce the risk of PM

The biggest benefits of a PM program occur through painting,lubrication, cleaning and adjusting, and minor componentreplacement to extend the life of equipment and facilities.


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Why and what has to be maintained

on breakers ?

Case

Mechanism

Arc chute

Main contacts Control unit

Connection systems

Auxiliary Devices

Communication system

Example for Breaker Maintenance


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Maintenance of case Function of case :

- isolate the main contacts and protect from arcingeffects

- support the mechanism, tripping device, auxiliarydevices, terminals

- Must withstand the stresses during short circuit

Damaged case is the consequence of

- shocks,

- moisture,

- high short circuit,

- overheating ( loose connection)

Preventive maintenance includes :

- visual inspection of dust, dirt, grease, moisture,cracks, soot,

- cleaning, ( dust, dirt, soot,) with dry cloth, brush orvacuum cleaner

- replacement in case of cracks


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Maintenance of the mechanism

Breaker mechanism

- Spring energy on Masterpact- Tumbler on Compact NS

- operate the contacts to establish and interruptthe circuit

Chassis mechanism

- to rack in and out the breaker, test the breaker


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Jammed mechanism is the consequence of :dust :

shocks : bending of mechanical partcorrosive atmosphere : rust and corrosionof metallic partNo operation for a long time

Preventive maintenance includes :dust removal : vacuum cleanerrecommendedcleaning : dry cloth, brush, solventprohibitedgreasing : only Schneider recommendedgreases, in small quantity

operation of breaker / chassis : to give thespring charged energy and themechanism their original characteristics

Maintenance of the mechanism Contd.


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Maintenance of the arc chute (Power breaker only)

Function of arc chute :- splitters : extinguish the arc and

absorb the energy under normalcondition and electric fault- filter : blow the pressured gas

out , cool down the gas

Arc chute deteriorates- under In : the insulation material

of the arc chamber can perforate- under Icc : the metal part is

vaporised


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Maintenance of main contacts (Power breaker only) Contd.

Arc chute in bad condition may resultin a non interruption of the arc,

decrease of the isolating function andultimately destruction in case of highshort circuit current.

Filters : avoid compound (made ofdust + grease) covering the filter

Preventive maintenance includes :periodic inspection after a fault :splitters should not present holesand be too thin, plastic part shouldnot have holes ( decrease of

insulation level)replacementcleaning of filter


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Maintenance of main contacts (Power breaker only) Function of main contacts :

- To make or break the circuit under normal (

In) or fault conditions (overload and Short-circuit )

Contacts get worn during each mechanicaland electrical open / close operation andafter short circuit ( maxi 2 cycles at Icu)

Worn contacts will result in :

- over heating of the breaker ( increase ofcontact resistance)

- decrease of life expectancy

- measurement of individual pole resistancereplacement


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Worn contacts will result in :over heating of the breaker ( increase of

contact resistance)decrease of life expectancy

Preventive maintenance includes :periodic visual check, control of themechanical contact wear indicator and

electronic wear indicator on Micrologic P &Hmeasurement of individual pole resistancereplacement

Preventive maintenance includes :periodic visual check, control of the

mechanical contact wear indicator andelectronic wear indicator on Micrologic P &H


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Maintenance of electronic control unit

Function of control unit :

- permanently analyse the phase current compare it to the protection set and in case of fault

trips the breaker

Control unit is sensitive to :

- environment : ambient temperature, humidity, corrosive atmosphere,

- operating conditions : vibration, electro-magnetic field,

A malfunctioning of the trip unit will result in :

- a non interruption of the fault current

- damage of equipment and breaker


- periodic push to trip test or trip test- control of the complete tripping channel

- curve adjustment

- saving of log event, settings ( Micrologic P & H)


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Maintenance of thermal-magnetic trip unit

Function of thermal-magnetic trip unit :

- Connected permanently in series with the phase currents

- based on the bending of a bimetal for overload and the movement of a magnet in a strongmagnetic field

Thermal -magnetic trip unit is sensitive to :

- ambient temperature, corrosive atmosphere

A malfunctioning of the trip unit will result in :

- a non interruption of the fault current

- damage of equipment and breaker


- primary injection test to trip the breaker

M i t f ti t


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Maintenance of connection systems Function of connection systems :

- Link together various types of devices by mean of electricaldistribution systems (bus bars, cables, auxiliary wires, ).

Bad connection ( too tight or too loose) will result in :

- Thermal effect leading to destruction of devices

- short circuit or fire


- For fixed connectors : No need of control if done with Schneiderrecommendation . otherwise : check temperature rise, if loose,dismantle and tighten with new screws, bolts & washers

- For sliding connectors : (mainly chassis)

- periodic cleaning and greasing with Schneider

recommended grease

- if corrosive atmosphere ( SO2 / H2S) : clean withspecial solution ( Thioure) and re grease

- Wires : check tightening and the insulation material

i f ili d i


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Maintenance of auxiliary devices

Function of auxiliary devices :

- Shunt trip release, under voltage release, OF contacts,

SD/SDE alarm contacts , electrical motor MCH Malfunctioning of the auxiliary device will result in a wrong

operation of the breaker

the consequences can be :- no safety operation ( emergency)

- wrong operation in the circuit

Preventive maintenance includes :- functional test of auxiliary device at nominal voltage

- replacement

PPM S h d l F T hi (M i P l)


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PPM Schedule For Township(Metering Panel)

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Sl No

Name of the

Cluster

Name of

the block

Date of PPM to

be carried outPPM start time PPM end time

Activity to be carried out

1 A & B 11/5/2012 9:00 15:00

All eletrical panel( Metering Panel, Utility Panel )

cleanning & all Basbas & cable conection check &

tightness

2 C & D 11/6/2012 9:00 15:00



tightness

3 E & F 11/7/2012 9:00 15:00



tightness

4 G & H 11/8/2012 9:00 15:00



tightness

5 J ,K & L 11/9/2012 9:00 15:00



tightness

6 M & N 11/10/2012 9:00 15:00



tightness

7 O & P 11/12/2012 9:00 15:00



tightness

8 Aminety 11/15/2012 9:00 15:00

Electrical Panel Cleaning & all busbar & cable connection

check & tightness

9 A & B 11/16/2012 9:00 15:00

All eletrical panel( Metering Panel, Utility Panel)


tightness

10 C , D & E 11/17/2012 9:00 15:00



tightness

11 F & G 11/19/2012 9:00 15:00



tightness

12 J & K 11/20/2012 9:00 15:00



tightness

13 Aminety 11/21/2012 9:00 15:00

Electrical Panel Cleaning & all busbar & cable connection

check & tightness

Koel

Sankha

PPM Schedule For Township(Substations)


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34

Sl No

Name of the

Cluster

Name of the

block

Date of PPM to be

carried outPPM start t ime PPM end time

Activity to be carried out Efected Area

1 LT Panel # 6 1-Mar-13 9:00 15:00

Eletrical Feeder panel cleanning , Breaker Rackout,Rackin

check, Breaker Contact check. All Busbar & cable conection

check & tightness

SA/SB,SC/SD,WTP,PROJECT

OFFICE,KA/KB,KC/KD/KE,

KF/KG,KH/KJ,KF/KG

2 LT Panel # 7 2-Mar-13 9:00 15:00



check & tightness

SE/SF,SG/SH,SJ/SK/SL,

SM/SN,SO/SP,COMMERCIAL

LT Panel # 5 3-Mar-13 9:00 15:00



check & tightness SPARE

3 LT Panel # 3 4-Mar-13 9:00 15:00



check & tightness

STUDIO/MA/MB,MC/MD/ME,

MF/MG

4 LT Panel # 4 5-Mar-13 9:00 15:00



check & tightness

MAINGATE/BANGALOW/

HOSTEL

5 LT Panel # 1 6-Mar-13 9:00 15:00



check & tightness

HATI BLOCK/COMMUNITY

CENTER,TEMPLE,APPOLO

6 LT Panel # 2 7-Mar-13 9:00 15:00



check & tightness BRAHMANI BLOCK

Substation # 3

Substation # 1

Substation # 2

PPM Schedule For Township(Substations)


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THANK YOU

Ppm pre-preventive maintenance of electrical

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