Installation and Commissining of Transformer

8/12/2019 Installation and Commissining of Transformer

1/27

three-phase HV / LV transformersmineral oil-immersed distribution models

Instructions forinstallation,

commissioning

and maintenance

Contents

taking delivery 3

handling 4

insta lla tion 6

HV and LV connections 15

transformer opera tion in para llel 19

maintenance 20

a fter-sa les service 23precommissioning checks 24


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2 France Transfo

Warning

This g uide intended for s ta nda rdrange oil-immersed distribution

tra nsformers a s des cribed inFra nce Transfo prod uctcatalogues.

If in doub t, our After-Sa les S ervicerema ins wholly a t your dispos a l.

Tl. (33) 03 87 70 57 72

fax: (33) 03 87 70 56 21


3/27


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4 France Transfo

Tra nsformers a re usually s ta bilised during tra nsit by hea vy timber bea rers fixed tothe vehicle bed. It is therefore essential to remove these bearers before lifting thetra nsformer unit o ff the vehicle.

Tra nsformer units incorporate spec ific ha ndling devices .

Lifting by means of slings or a lifting beam(figure 1)

The unit must be ha ndled using the 2 lifting rings loc a ted on the tra nsformer cover.

Hauling(figure 2)

The tra nsformer must o nly be ha uled from its chassis . 30 mm dia meter holes havebeen drilled in the ends of cha ssis memb ers for this purpos e, except in the ca seof low ca pa city units or those built to a spec ia l spec ifica tion. Ha uling must onlybeen undertaken in two direc tions : a long a nd perpendicula r to the chassis centre-line.

Handling using a forklift truck(figure 2)

Forks must only lift the cha ssis from within the inverted c ha nnel sec tions , w ith idlerrollers remo ved .

or

1

hole for hauling

2

Handling


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Positioning of idler rollers(figure 3) either by lifting with slings or a lifting beam.

or by lifting with a forklift truck.In this case, position the forks of the truck within the inverted channel sections.Place heavy timber bearers, which are slightly higher than the idler rollers, cross-wise benea th the ends o f the c has sis members a nd low er the unit onto these tim-

bers.Position jacks and remove timber bearers one by one.At the same time, fix each idler roller in the required position (idlers swivel in2 direc tions ) using the loc king screw.Then, remo ve the jacks a nd a llow the unit to res t on its idler rollers.Ground clearance due to the idler rollers is essential for transformer cool-ing.

3

timber bearer idler rollers

Handling


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Ensure that machine characteristics shown on the rating plate correspond withinsta lla tion cond itions : prima ry vo lta ge(s), ta pping links.

This pla te ma y be moved a nd a ttached to a ny side o f the tank so that it is vis ibleonc e the ma chine is in position.

In general, insta lla tion must c omply w ith the requirements of IEC S tanda rd

71-1, 2 a nd 3 in rela tion to insula tion co-ordina tion.

E.g.: c a se of overhead-underground connection to be protec ted by lightninga rres ters insta lled a t bo th ends of the HV ca ble.

unit to be insta lled a t a ma ximum a ltitude o f 1000 m, unless otherwise s pec ifiedwith order, beca use a ir ra refaction a dversely a ffec ts c oo ling o f the w indings .

unless otherwise specified with order, transformers of standard design are

sized in accorda nce with IEC S tanda rd 76 for the follow ing a mbienttemperatures:

ma ximum : 40 C a vera ge da ily : 30 C a vera g e a nnua l : 20 C minimum : 25 C

When the transformer is live, the a mbient tempera ture inside the pla ntroo m mus tco mply with the abo ve values, unless the tra nsformer has been spec ia lly des ignedon the ba sis o f a pa rticula r spec ifica tion.

Installation


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7France Transfo

Determining the height and cross-sectional areas ofventilation wall openings (figure 4)In the general ca se involving na tura l coo ling (AN), the purpose o f the plantroomventila tion s ystem is to d isperse the hea t, resulting from the tota l hea t los sesgenerated by the operating transformer, by natural convection.

An efficient ventilation system comprises a fresh air inlet wall opening of cross-

sectiona l a rea S pos itioned low down in the room, a nd a ir outlet opening of cros s-sectional area S' positioned high up on the opposite wall of the room at a heightH above the air inlet opening.

It should be noted that res tric ted a ir c ircula tion a round the unit ca uses a reductionin availa ble power. For this reason, the tra nsformer must be positioned a t aminimum distance of 200 mm from any solid wall.

Design calculation:

P = sum of los ses under no loa d a nd losses d ue to loa d on tra nsformer, expressedin kW a t 75 C , plus los ses generated by a ny other unit in the sa me room.

S = cros s-sec tiona l a rea of fresh a ir inlet wa ll opening (deduc t pos sible a reaob structed by grill), expressed in m2.

S = cross -sec tiona l a rea of a ir outlet w a ll opening (ded uct pos sible a reaob structed by grill), expressed in m2.

H = differenc e in height between inlet a nd outlet w a ll opening c entre-lines ,expressed in m.

and

This formula is va lid for an a vera ge a nnua l a mbient temperature of 20 C a nd a t amaximum altitude of 1000 metres.

H

S

S

Groupe M erl in Gerin Us i ne de M aiz ires -ls -M etz (M os el le) Franc en216540

4

200 mmmini

S0 18P,

H-----------------= S 1 10 S,=

Installation


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8 France Transfo

Forced ventilation of plantroom (figure 5)A ventilation system of this type is required for a cramped or poorly ventilatedpla ntroom, or for a room in w hich the a mbient tempera ture is much higher than thetempera ture outside , in view of the a mbient tempera tures used for designing thetra nsformer. S hould the trans former be freq uently overloa ded, a forced ventila tionsystem c a n help to d isperse the hea t generated by the unit, a lthough it will not

reduce the a dverse effects o f such overloa ding on the eq uipment's life.An air extract fan discharging outside the plantroomma y be fitted to the outletwa ll opening, loc a ted a t high level, in order to increase na tura l convec tion in theroom; this fan can be thermostat-controlled.

Recommended disc harge ra te (m3/s) a t 20 C = 0.10 P

P = tota l hea t los ses to be dispersed , expressed in kW, for a ll eq uipment insta lled .

GroupeM erl inGerin Us ine de M aiz ires -ls -M etz (M os elle) Franc e n216540

H

S

S

5

200 mmmini

Installation


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9France Transfo

Setting the voltagecommutator

Commutator setting is ca rried out in thefollow ing w ay:

- unscrew fully the red locking knob,

- s imultaneous ly pull a nd turn thecommutato r rota ting hea d until thepointer indicates the right setting,

- push the rota ting head ba ck ensuringthat the pointer is enga ged in thenotch for the setting req uired ,

- rescrew fully the red loc king knob

Tapping links

Set the tapping pointcommutator to the requiredposition:

Pos. 1: upper primary voltagePos. 2: ra ted prima ry voltage

Pos. 3: lower primary voltage

red locking knob

commutator rotating headindex

Adjustments to tapping point orvoltage commutators must beundertaken with the transformer

off-load and de-energized.

1

2

Double primary voltage

For units using 2 primaryvoltages, s elec t pos ition a srequired.

Pos. 1: HV1

Pos. 2: HV2

Installation


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Statutory restrictions for oil-immersed transformersEach c ountry issues its ow n regula tions covering the insta lla tion of o il-immersedtra nsformers on its territory.These regula tions invaria bly respond to conc erns for the protec tion of people,property a nd the environment. Available protec tion s ystems depend on thetechnolog y a dopted for the transformer co ncerned.

When the unit is in service, the volume o f the d ielec tric fluid used to coo l its coils(usua lly mineral oil complying with IEC S ta nda rd 296) varies continua lly, d ue totemperature variations in the windings.These volume changes must be " a bs orbed" by a suitab le expansion sys temwhich has g iven rise to tw o d is tinct tec hnolog ies :

Hermetically sealed type transformerThe unit's ta nk, conta ining the a ctive pa rt, is hermetica lly sea led : va ria tions involume are a bs orbed by expa nsion of the co oling fins positioned a round the ta nk,the d ielec tric fluid is not exposed to the s urrounding a ir.

Maintenance of this type o f unit is thus g rea tly reduced (see pa ge 20).

Installation


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Protection accessory: the protection relay (figure 6)Fitted direc tly to the trans former co ver, this rela y ens ures protec tion a ga instinterna l faults , prolonged overvoltages a nd fire risks a ssoc ia ted w ith the use o finflammable dielectric fluids.

The a cc essory co ntinuously mo nitors:- dielec tric fluid level,

- tank internal press ure,- dielec tric fluid temperature a t two d ifferent thresholds .

To operate properly, the protection rela y must be fully filled w ith fluid (level higherthan the float visible in the transparent section of the unit). If this is not the case,chec k the instructions which a ppea r inside ea ch ca sing.

To ensure optimum protection, the follow ing a ction a nd adjustments a re

recommended:Finding Recommended

adjustmentFault detected Action to be taken

Gas emitted or drop inlevel

Large floa t at the top Serious fault De-energize unit

P ressure switch 0.20 bar Serious fault De-energize unit

Thermostat threshold 1 90 C

Overvoltages

Activate alarmThermostat threshold 2 100 C Overvoltages De-energize unit

6

oil

sensors

Installation


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12 France Transfo

Faults detected on live transformer unit Dielec tric fluid level is detected a s low

The protec tion rela y is empty a nd the la rge floa t is a t the bo ttom.Ma y be due to:- a ir entering; there must be a dielec tric fluid lea k a nd thus o ily s ta ins s hould b e

vis ible on the ground.Accura tely loc a lise the fault, c a rry out repa ir, then rec heck the level with thebo dy o f fluid a t a temperature of 20 C, before sw itching the unit live a ga in(see oil gra des , pa ge 20),

- internal ga s emiss ion: ga s should b e s a mpled using a syringe a nd then ana ly-sed.Whils t a wa iting results, under no c ircumsta nces should the tra nsformer beswitched live again because a risk of total destruction exists.

S hould g a s a na lysis revea l a n inflamma ble ga s , conta ct FRANCE TRANS FOAfter-Sales Service (see page 23), or your SCHNEIDER correspondent.

Overheating is detectedThis ma y be due to :- improper cooling o f the transformer (insuffic ient a ir flow a round unit or pla nt-

room ventila tion),- continuous overvoltag e.

Excess pressure is detec tedThis ma y be due to :- overhea ting: see abo ve,- internal ga s emiss ion: see a bove,- topping up of dielec tric fluid w ith the body of fluid below 20 C ; drain the

overflow with the tra nsformer de-energised a nd the d ielec tric fluid a t 20 C .

Installation


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13France Transfo

Breather type transformer with expansion tank (figure 7)The tra nsformer tank is connec ted by pipew ork to a n expansion tank, mounteda bo ve the unit, w hich ens ures tha t the dielec tric fluid level rema ins suffic iently highin the transformer tank: variations in dielectric fluid volume are absorbed by theexpansion tank which remains at atmospheric pressure.

This type o f unit therefore requires ma intena nce w hich is both regula r a nd s uited

to the c lima tic cond itions in the vicinity o f the transformer (see pa ge 21).Protection accessory : the Buchholz relay

Fitted to the pipework linking the expansion tank to the transformer tank, thisa ccessory ensures protec tion aga inst interna l faults only, by monitoring dielec tricfluid levels a nd fluctua tions .

To ensure proper opera tion, the Buchholz rela y must be completely bled of air.

Faults detected on live transformer unit

Dielectric fluid level is detected as low.The B uchholz rela y is pa rtia lly empty, the top level floa t is a t the bottom.Rea sons for this low fluid level a re the s a me a s those g iven for the protec tionrelay (see pa ge 11) but in the present c a se, the rela y w ill activa te a utoma tica llythe a la rm.

Major discharge of oil towards the expansion tank is detectedA violent emission of g a s , resulting in serious elec trica l faults within thetransformer ta nk, lea ds to a la rge discharge of oil to the expa nsion tank, whichcauses the Buchholz relay bottom float to pivot; the transformer unit must bede-energised immed ia tely a nd permanently.Conta ct FRANCE TRANSFO After-Sa les S ervice (see pa ge 23), or your

S CHNEIDER correspondent.

7oil

Installation


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14 France Transfo

Dielectric fluid retention systemIn an environmenta l protec tion c ontext, the retention s ystem used must beca pa ble o f conta ining the tota l q uantity of d ielec tric fluid, unless otherwisespec ified by loc a l regula tions .

It ma y comprise :- a ra ised door threshold if the pla ntroom floo r is o il tight,

- a low oil tight wa ll a round the tra nsformer,- a steel trough pos itioned benea th the tra nsformer.

In the la st tw o c a ses, ens ure that the system d oes not adverse ly a ffec t tra nsformercooling by preventing air circulation around the tank cooling fins.

Installation


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Assembly and tightening torqueBushings must not be subjec ted to stresses resulting from c a ble or busbarco nnections ; such loa ds ca n ca use lea ks a t va rious joints.

Furthermore, the following connection details and tightening torque values shallbe complied w ith:

F

HV or LV connection to porcelain bushing(U 52 kV - M12 stud)

nut tighteningtorque: 25 Nm

M12 brass stud

loa d in ac cordancewith I.E.C. 137:

co nnecting terminalinclined < 30 , F = 50 daN

co nnecting terminalinclined > 30 , F = 30 daN

clearance:

approx.5mm

reminder:

1 N.m = 0.102 mkg

1 mkg = 0.98 da N.m

LV connection to busbar bushing

stee l bo ltlocknut

end lug

large diameter metric se riessteel plain washers

tin-pla ted co pper busbar bushing

N.B .: end lug, b olt and wa shers a re not supplied.

HV and LV connections


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Table of tightening torque values

Tightening torque g iven in N.m.

Tightening tolera nce 20%.The a bove torque va lues a re for a ssemblies inco rporating plain wa shers .However, w e recommend the incorpora tion o f contac t w a shers behind the pla inwa shers; the a bove torq ue values s hould be increa sed by 35% if this is done.

S teel a nd s ta inless s teel bo lts shall be greased prior to fitting.

If a luminium bo lts a re used, plea se refer to ma nufa cturer's recommenda tions .

Bolts Class 6.8anticorrosion-treated steel

Class A2-70and A4-70stainless steel

Class A2-80and A4-80stainless steel

Brass

M8 15.2 15.5 17.7 7.6

M10 30 30 35 15.1M12 52 53 60 25

M14 83 85 97 41

M16 130 133 152 55



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18 France Transfo

ProtectionHV bushings

Dra w-out c onnec tors (s tra ight or a ngle) ma y be kept plugg ed into the plug-inbushings using a padlockable locking device (padlock /lock not supplied);Relea se of this loc king s ystem ma y be ma de conditiona l on prior isola tion ofthe transformer from the HV supply (figure 8);

P orce la in bushings ma y be fitted with a sea la ble protec tive cover, w hosedesign w ill depend on the HV voltages , the configura tion a nd number of ca bles .

LV bushings

Busba r or porcela in bushings ma y be protec ted b y a sea la ble cover.

8



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19France Transfo

Connec tion o f severa l tra nsformers in pa ra llel lea ds to the follow ing cons tra ints: If their power outputs a re d ifferent, the tota l ava ila ble c ombined pow er output

will be s lightly les s (< 10%) tha n the s um of the power outputs for eachtransformer coupled sepa ra tely.

The power output of the la rges t tra nsformer should no t be more than tw ice tha tof the smallest unit.

Tra nsformers must be supplied by the s a me network.

Connections must be of the sa me length a nd ha ve simila r cha ra cteristicsbetw een the LV termina ls of the different units a nd the c oupling circuit-brea ker(figure 9).

Couplings must b e identica l.

S hort-circuit volta ges must be identica l ( 10%).

Differences in secondary voltages between the different units must not exceed 0.4%.

The switch sha ll be positioned identica lly on ea ch unit.

9recommend to advise

LV

Transformer operation in parallel


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20 France Transfo

Mineral oil and component materialsThe trans former is filled with minera l oil complying with ICE Sta nda rd 296.

Tra nsformer component ma teria ls a re free o f polychlorob iphenyls (P CB 's),polychloroterphenyls (P CT's ) a nd polychlorobenzyltoluene (P CBT).Moreover, the P CB co ntent of this unit is gua ra nteed to be less than the detecta blethres hold (2 ppm*) in s tric t complia nce w ith s ta nda rds currently in force .

Hermetically sealed type transformerUnder normal opera ting a nd environmenta l cond itions , ma intenance of thistransformer is reduced. It is in fact limited to regularly checking the tightness ofconnec tions a nd visual inspec tion o f transformer oil tightness .Under conditions of extreme pollution (depositing of dust, salt, chemicals, etc.),cleaning of porcelain or busbar bushings may be required.

As long a s the dielec tric fluid has not been exposed to the a ir for a pa rticula rrea son (tank opening, repa irs , fitting of a ccessories , topping up of o il, e tc.), onedielec tric withsta nd test, on a sa mple ta ken from the bottom of the tank (minimumbrea kdow n voltage 30 kV), every 10 yea rs is suffic ient.The tra nsformer is hermetica lly sea led a nd ha s no g a s cushion. In other words ,filling a nd c los ure have been ca rried out in such a w a y that pressures a re ba la nced(internal and external atmospheric pressure) under conditions approaching

normal, i.e. temperature of 20 C and press ure of 1013 mba r.

* pa rts per million.

Ce transformateurest garanti ralisavec des

constituants neufs etexempts detoutlmentde

rcuprationsusceptibledavoirt pollupar

des PCB .

We warrantthat this transformer has been

manufacturedwithnew materialandis totallyfree

fromsecondhandpa

rts pollutedwithPCBs .

Labelplaced

onalltransformers

Maintenance


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21France Transfo

If necessary, this transformer may be opened in accordance with the followingrecommendations:

Transformer is hot (> 20C)The unit's internal pres sure is higher than a tmospheric a nd opening it ca usesleakage of some dielectric fluid which can only be reinjected in full, once itstempera ture ha s returned to 20 C .Until this oc curs , the unit ca n fulfil its functions . How ever, replac ement of a ll the

dielec tric fluid los t a t the ea rlies t opportunity is preferable. Transformer is cold (< 20C)

The unit's internal pressure is low er tha n a tmos pheric a nd opening it c a uses adrop in oil level in the tank. After servicing and topping up dielectric fluid, ifreq uired, put the unit back into operation a nd purge w hen hot.To prevent excess pres sure in the ta nk, the volume of dielec tric fluid which ma yhave been a dd ed (during topping up) should b e dra ined, onc e the unit's

opera ting tempera ture has risen to 20 C.

Maintenance


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22 France Transfo

Breather type transformer with expansion tankBeca use the d ielec tric fluid is expos ed permanently to the s urrounding a ir, thefrequency of oil quality checks must be increased: once a year is an absoluteminimum, which should be further increased if a gradual deterioration of fluiddielec tric withsta nd is ob served (reminder: minimum b rea kdow n voltag e: 30 kV).If an a ir dehumidifier has been fitted to the expa nsion ta nk to filter the incoming a ir,the c olour of the s ilica gel it conta ins should be monitored:

- blue co lour : s ilica ge l is in a good c ond ition for ensuring d ehumidific a tion,- pink or white colour : s ilica ge l has a bs orbed humidity and ha s bec ome inef-

fective, it should therefore b e replaced (supplied by our After-Sa les S ervice,see page 23).

Also check tha t the g lass , loc a ted a t the b ottom o f the dehumidifier, is filled w ithoil to the req uired level, in order that dus t c a rried by the s urround ing a ir flow iseffectively reta ined .

Maintenance


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When ma king enq uiries or ordering spa re pa rts, it is es sentia l to q uote the ma incharacteristics given on the rating plate and, in particular, the unit serial number. TECHNICAL MEMO(data to be copied from unit rating plate)

No. :

Year :

P ow er output : kVA

Freq uency : Hz

Cooling :

Coupling :

Rated highvoltag e : kV

Low voltag e : V

Mas s of

dielec tric : kg

Tota l ma ss : kg

Groupe Schneider Usine de Maizires-ls-Metz (Moselle) France

NAL - 226489

complying ref.HzTREEPHASE TRANSFORMERaccording to year

impedancevoltage

connection%

high voltage low voltage

pos 3 V

voltages

pos 4 V

pos 1 V

pos 2 V

pos 5 V

currents A

V

A

kVA N insulation level KV

nature windings

primary in service on

cooling

dielectric

mass diel. kg

mass total kg

After-Sales Service

tel.: (33) 03 87 70 57 72

fax: (33) 03 87 70 56 21

After-Sales Service


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24 France Transfo

Operations prior to connecting transformer check da ta g iven on ra ting pla te in rela tion to needs (pow er output, voltage,

etc...)

ensure tra nsformer pla ntroom is clea n a nd c a nnot flood

ensure c orrec t ventila tion- pla ntroom a ir vents a re c lea r a nd of suitable a rea (pa ges 7 and 8)- suffic ient c lea ra nce be tween unit and s olid w a lls in pla ntroom (pa ge 7)- suffic ient c lea ra nce betw een unit a nd floor (unit res ting on idler rollers -

pag e 5)

check genera l condition a nd c lea nliness o f tra nsformer

measure values of insulation resistance using a 2,500 V insulation tester

If the mea sured values a re s ignific a ntly less than the usua l va lues, plea se ca llyour After-Sales Service (page 22).

check oil tightness of unit (welds , g a skets , va lves , d ra ins, plugs ).

Checks carried out on: ......................................... by: .........................................

Measuring points Measured values Usual values formineral oil

HV / earth

LV / earth

HV/LV

M

M

M

250 M

250 M

50 M

Precommissioning checks


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25France Transfo

Operations prior to switching transformer live ensure there is no foreign bod y on the unit (meta l filings , nuts a nd bo lts , etc .)

if the transformer is an hermetically sealed type unit fitted with a protectionrela y, check that the la rge floa t is a t the top a nd tha t the drain is properlyclosed (close by turning clockwise). Refer to instructions supplied with eachtra nsformer in rela tion to tes ting .

if the tra nsformer is a breather type unit w ith an expa nsion ta nk a nd B uchholzrela y, check tha t a ll a ir bubbles have been b led from the la tter unit a nd ca rryout rela y tes ting using the devices provided for this (rod to be pushed orpulled to a ctiva te a la rm o r trip).Check condition o f silica gel in the dehumidifier a nd the level of oil in the b ot-tom gla ss vessel.

ensure that c a bles a nd busba rs a re properly supported; no loa ds should b ea pplied to the tra nsformer connec tion lugs .

chec k wiring of protection or ventila tion auxilia ries with respec t to :- insula tion cleara nces a nd ca ble fixings,

operation.chec k tightness of connections (pages 16 and 17)

check earthing co ntinuity - to ensure the sa fety of operating personnel, the

transformer earthing system must be grounded. check that rota ting s witch head is c orrec tly se t to, a nd loc ked in, the req uired

position.

ensure that ventilation grills are clear.- if unit is to opera te in para llel, check short-circuit voltage, pha se cons is tency

and voltage ratio (page 19)

Precommissioning checks


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26 France Transfo

notes


27/27

Nident.TVA

:FR78357801109SAau

capitalde10280000FRFRCSMetzB357801109ImprimenFrance

France Transfo

BP 10140

F 57281 M aizires-ls-M etz C edex

Tel.: (33) 03 87 70 57 57

fax.: ( 33) 03 87 51 10 16

GEa 220000 a

Since this manual was edited, a number of alterations may havebeen incorporated in the equipment you have received. The solereason for this resides in our constant efforts to improve thequality and performance of our equipment.

Edited by: France Transfo - 03/99Typesetting and illustrations: COREDIT

Documents

Installation and Commissining of Transformer