Minera Notice Installation Anglais GEa220000b

7/27/2019 Minera Notice Installation Anglais GEa220000b

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

Instructions for

installation,commissioningand maintenance

Contents

taking delivery 3

handling 4

installation 6

HV and LV connections 15

transformer operation in parallel 19

maintenance 20

after-sales service 23

precommissioning checks 24

Minera

is becoming

France Transfo



France Transfo2

WarningThis guide intended for standardrange oil-immersed distributiontransformers as described inFrance Transfo productcatalogues.

If in doubt, our After-Sales Serviceremains wholly at your disposal.

Tél. (33) 03 87 70 57 72fax: (33) 03 87 70 56 21



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On receipt of equipment, ensure that it corresponds with your order by checkingmachine characteristics indicated on the rating plate (capacity, voltages, etc.)

Distribution transformers are delivered "ready for installation", i.e. completely filledwith oil and with accessories either fitted or delivered separately.

When unloading, check that the transformer has not been damaged duringtransport (broken insulators, damaged tank, etc.) and that all accessories orderedhave been delivered.

Also check that the tank lead seal, fixed to one of the cover screws (usually at atank corner) is intact, because its breakage causes the transformer guarantee tolapse.

Should the unit have been damaged or if accessories ordered are found to be

missing:

enter a reservation on the final haulage contractor's delivery note and confirmby recorded delivery letter within 3 days.

write a report and send it immediately to your supplier (France Transfo or adealer as the case may be).

Taking delivery of equipment and preliminary checking



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Transformers are usually stabilised during transit by heavy timber bearers fixed tothe vehicle bed. It is therefore essential to remove these bearers before lifting thetransformer unit off the vehicle.

Transformer units incorporate specific handling devices.

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

The unit must be handled using the 2 lifting rings located on the transformer cover.

Hauling (figure 2)

The transformer must only be hauled from its chassis. 30 mm diameter holes havebeen drilled in the ends of chassis members for this purpose, except in the caseof low capacity units or those built to a special specification. Hauling must only

been undertaken in two directions: along and perpendicular to the chassis centre-line.

Handling using a forklift truck (figure 2)

Forks must only lift the chassis from within the inverted channel sections, with idlerrollers removed.

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 beneath the ends of the chassis members and lower 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 directions) using the locking screw.Then, remove the jacks and allow the unit to rest 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 withinstallation conditions: primary voltage(s), tapping links.

This plate may be moved and attached to any side of the tank so that it is visibleonce the machine is in position.

In general, installation must comply with the requirements of IEC Standard

71-1, 2 and 3 in relation to insulation co-ordination.

E.g.: case of overhead-underground connection to be protected by lightningarresters installed at both ends of the HV cable.

unit to be installed at a maximum altitude of 1000 m, unless otherwise specifiedwith order, because air rarefaction adversely affects cooling of the windings.

unless otherwise specified with order, transformers of standard design aresized in accordance with IEC Standard 76 for the following ambienttemperatures:

• maximum : 40°C• average daily : 30°C• average annual : 20°C• minimum : – 25°C

When the transformer is live, the ambient temperature inside the plantroom mustcomply with the above values, unless the transformer has been specially designed

on the basis of a particular specification.

Installation



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Determining the height and cross-sectional areas ofventilation wall openings (figure 4)

In the general case involving natural cooling (AN), the purpose of the plantroomventilation system is to disperse the heat, resulting from the total heat lossesgenerated by the operating transformer, by natural convection.

An efficient ventilation system comprises a fresh air inlet wall opening of cross-sectional area S positioned low down in the room, and air outlet opening of cross-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 restricted air circulation around the unit causes a reductionin available power. For this reason, the transformer must be positioned at a

minimum distance of 200 mm from any solid wall.

Design calculation:

P = sum of losses under no load and losses due to load on transformer, expressedin kW at 75°C, plus losses generated by any other unit in the same room.

S = cross-sectional area of fresh air inlet wall opening (deduct possible areaobstructed by grill), expressed in m2.

S’= cross-sectional area of air outlet wall opening (deduct possible areaobstructed by grill), expressed in m2.

H = difference in height between inlet and outlet wall opening centre-lines,expressed in m.

and

This formula is valid for an average annual ambient temperature of 20°C and at amaximum altitude of 1000 metres.

H

S

S’

G r oupe M er lin G erin · Usi ne deM aizièr es- lès- M etz ( M oselle) F r a n c e n º 216540

4

200 mmmini

S0 18P,

H-----------------= S′ 1 10 S×,=

Installation



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Forced ventilation of plantroom (figure 5) A ventilation system of this type is required for a cramped or poorly ventilated

plantroom, or for a room in which the ambient temperature is much higher than thetemperature outside, in view of the ambient temperatures used for designing thetransformer. Should the transformer be frequently overloaded, a forced ventilationsystem can help to disperse the heat generated by the unit, although it will notreduce the adverse effects of such overloading on the equipment's life.

An air extract fan discharging outside the plantroom may be fitted to the outletwall opening, located at high level, in order to increase natural convection in theroom; this fan can be thermostat-controlled.

Recommended discharge rate (m3 /s) at 20°C = 0.10 P

P = total heat losses to be dispersed, expressed in kW, for all equipment installed.

G r oupe M er lin G erin · Usi ne deM aizi èr es-lès- M etz ( M oselle) F r a n c e n º 216540

H

S

S’

5

200 mmmini

Installation



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Setting the voltagecommutator

Commutator setting is carried out in thefollowing way:

- unscrew fully the red locking knob,- simultaneously pull and turn the

commutator rotating head until thepointer indicates the right setting,

- push the rotating head back ensuringthat the pointer is engaged in thenotch for the setting required,

- rescrew fully the red locking knob

Tapping links

Set the tapping point

commutator to the requiredposition:

Pos. 1: upper primary voltage

Pos. 2: rated primary voltage

Pos. 3: lower primary voltage

red locking knob

commutator rotating head index

Adjustments to tapping point orvoltage commutators must beundertaken with the transformeroff-load and de-energized.

1

2

Double primary voltage

For units using 2 primaryvoltages, select position asrequired.

Pos. 1: HV1

Pos. 2: HV2

Installation



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Statutory restrictions for oil-immersed transformersEach country issues its own regulations covering the installation of oil-immersed

transformers on its territory.These regulations invariably respond to concerns for the protection of people,property and the environment. Available protection systems depend on thetechnology adopted for the transformer concerned.

When the unit is in service, the volume of the dielectric fluid used to cool its coils(usually mineral oil complying with IEC Standard 296) varies continually, due totemperature variations in the windings.These volume changes must be "absorbed" by a suitable expansion systemwhich has given rise to two distinct technologies:

Hermetically sealed type transformerThe unit's tank, containing the active part, is hermetically sealed: variations involume are absorbed by expansion of the cooling fins positioned around the tank,the dielectric fluid is not exposed to the surrounding air.

Maintenance of this type of unit is thus greatly reduced (see page 20).

Installation



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Protection accessory: the protection relay (figure 6)

Fitted directly to the transformer cover, this relay ensures protection againstinternal faults, prolonged overvoltages and fire risks associated with the use ofinflammable dielectric fluids.

The accessory continuously monitors:- dielectric fluid level,- tank internal pressure,- dielectric fluid temperature at two different thresholds.

To operate properly, the protection relay must be fully filled with fluid (level higherthan the float visible in the transparent section of the unit). If this is not the case,check the instructions which appear inside each casing.

To ensure optimum protection, the following action and adjustments arerecommended:

Finding Recommendedadjustment

Fault detected Action to be taken

Gas emitted or drop inlevel

Large float at the top ➩ Serious fault ➩ De-energize unit

Pressure switch 0.20 bar ➩ Serious fault ➩ De-energize unit

Thermostat threshold 1 90°C ➩ Overvoltages ➩ Activate alarm

Thermostat threshold 2 100°C ➩ Overvoltages ➩ De-energize unit

6

oil

sensors

Installation



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Faults detected on live transformer unit

Dielectric fluid level is detected as lowThe protection relay is empty and the large float is at the bottom.May be due to:- air entering; there must be a dielectric fluid leak and thus oily stains should be

visible on the ground. Accurately localise the fault, carry out repair, then recheck the level with thebody of fluid at a temperature of 20°C, before switching the unit live again(see oil grades, page 20),

- internal gas emission: gas should be sampled using a syringe and then analy-sed.Whilst awaiting results, under no circumstances should the transformer be

switched live again because a risk of total destruction exists.Should gas analysis reveal an inflammable gas, contact FRANCE TRANSFO After-Sales Service (see page 23), or your SCHNEIDER correspondent.

Overheating is detectedThis may be due to:- improper cooling of the transformer (insufficient air flow around unit or plan-

troom ventilation),- continuous overvoltage.

Excess pressure is detected

This may be due to:- overheating: see above,- internal gas emission: see above,- topping up of dielectric fluid with the body of fluid below 20°C; drain the over-

flow with the transformer de-energised and the dielectric fluid at 20°C.

Installation



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Breather type transformer with expansion tank (figure 7)The transformer tank is connected by pipework to an expansion tank, mounted

above the unit, which ensures that the dielectric fluid level remains sufficiently highin the transformer tank: variations in dielectric fluid volume are absorbed by theexpansion tank which remains at atmospheric pressure.

This type of unit therefore requires maintenance which is both regular and suitedto the climatic conditions in the vicinity of the transformer (see page 21).

Protection accessory : the Buchholz relay

Fitted to the pipework linking the expansion tank to the transformer tank, thisaccessory ensures protection against internal faults only, by monitoring dielectricfluid levels and fluctuations.

To ensure proper operation, the Buchholz relay must be completely bled of air.

Faults detected on live transformer unit

Dielectric fluid level is detected as low.The Buchholz relay is partially empty, the top level float is at the bottom.Reasons for this low fluid level are the same as those given for the protectionrelay (see page 11) but in the present case, the relay will activate automaticallythe alarm.

Major discharge of oil towards the expansion tank is detected

A violent emission of gas, resulting in serious electrical faults within thetransformer tank, leads to a large discharge of oil to the expansion tank, whichcauses the Buchholz relay bottom float to pivot; the transformer unit must bede-energised immediately and permanently.Contact FRANCE TRANSFO After-Sales Service (see page 23), or yourSCHNEIDER correspondent.

7

oil

Installation



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Dielectric fluid retention systemIn an environmental protection context, the retention system used must be

capable of containing the total quantity of dielectric fluid, unless otherwisespecified by local regulations.

It may comprise:- a raised door threshold if the plantroom floor is oil tight,- a low oil tight wall around the transformer,- a steel trough positioned beneath the transformer.

In the last two cases, ensure that the system does not adversely affect transformercooling by preventing air circulation around the tank cooling fins.

Installation



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Assembly and tightening torqueBushings must not be subjected to stresses resulting from cable or busbarconnections; such loads can cause leaks at various joints.

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

F

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

nut tighteningtorque: 25 Nm

M12 brass stud

load in accordancewith I.E.C. 137:

connecting terminalinclined < 30°, F = 50 daN

connecting terminalinclined > 30°, F = 30 daN

c l e a r a n c e :

a p p r o x . 5 m m

reminder:

1 N.m = 0.102 mkg

1 mkg = 0.98 daN.m

LV connection to busbar bushing

steel boltlocknut

end lug

large diameter metric seriessteel plain washers

tin-plated copper busbar bushing

N.B.: end lug, bolt and washers are not supplied.

HV and LV connections



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Table of tightening torque values

Tightening torque given in N.m.

Tightening tolerance ± 20%.

The above torque values are for assemblies incorporating plain washers.However, we recommend the incorporation of contact washers behind the plainwashers; the above torque values should be increased by 35% if this is done.

Steel and stainless steel bolts shall be greased prior to fitting.

If aluminium bolts are used, please refer to manufacturer's recommendations.

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 15.1

M12 52 53 60 25

M14 83 85 97 41

M16 130 133 152 55




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ProtectionHV bushings

Draw-out connectors (straight or angle) may be kept plugged into the plug-inbushings using a padlockable locking device (padlock / lock not supplied);Release of this locking system may be made conditional on prior isolation ofthe transformer from the HV supply (figure 8);

Porcelain bushings may be fitted with a sealable protective cover, whosedesign will depend on the HV voltages, the configuration and number of cables.

LV bushings

Busbar or porcelain bushings may be protected by a sealable cover.

8




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Connection of several transformers in parallel leads to the following constraints:

If their power outputs are different, the total available combined power outputwill be slightly less (< 10%) than the sum of the power outputs for each

transformer coupled separately.

The power output of the largest transformer should not be more than twice thatof the smallest unit.

Transformers must be supplied by the same network.

Connections must be of the same length and have similar characteristicsbetween the LV terminals of the different units and the coupling circuit-breaker(figure 9).

Couplings must be identical.

Short-circuit voltages must be identical (±10%).

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

The switch shall be positioned identically on each unit.

9recommend to advise

LV

Transformer operation in parallel



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Mineral oil and component materials

The transformer is filled with mineral oil complying with ICE Standard 296.

Transformer component materials are free of polychlorobiphenyls (PCB's),polychloroterphenyls (PCT's) and polychlorobenzyltoluene (PCBT).Moreover, the PCB content of this unit is guaranteed to be less than the detectablethreshold (2 ppm*) in strict compliance with standards currently in force.

Hermetically sealed type transformer

Under normal operating and environmental conditions, maintenance of thistransformer is reduced. It is in fact limited to regularly checking the tightness ofconnections and visual inspection of 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 as the dielectric fluid has not been exposed to the air for a particularreason (tank opening, repairs, fitting of accessories, topping up of oil, etc.), onedielectric withstand test, on a sample taken from the bottom of the tank (minimumbreakdown voltage 30 kV), every 10 years is sufficient.The transformer is hermetically sealed and has no gas cushion. In other words,filling and closure have been carried out in such a way that pressures are balanced(internal and external atmospheric pressure) under conditions approachingnormal, i.e. temperature of 20°C and pressure of 1013 mbar.

* parts per million.

C e t r a n s f o r m a t e u r e s t g a r a n t i r é a l i s é a v e c d e s

c o n s t i t u a n t s n e u f s e t e x e m p t s d e t o u t é l é m e n t d e

r é c u p é r a t i o n s u s c e p t i b l e d ’ a v o i r é t é p o l l u é p a r

d e s P C B.

W e w a r r a n t t h a t t h i s t r a n s f o r m e r h a s b e e n

m a n u f a c t u r e d w i t h n e w m

a t e r i a l a n d i s t o t a l l y f r e e

f r o m s e c o n d h a n d p a r t s p o l l u t e d w i t h P C

B ’ s.

L a b e l p l a c e d o

n a l l t r a n s f o r m

e r s

Maintenance



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

Transformer is hot ( θ > 20°C)

The unit's internal pressure is higher than atmospheric and opening it causesleakage of some dielectric fluid which can only be reinjected in full, once itstemperature has returned to 20°C.Until this occurs, the unit can fulfil its functions. However, replacement of all thedielectric fluid lost at the earliest opportunity is preferable.

Transformer is cold ( θ < 20°C)The unit's internal pressure is lower than atmospheric and opening it causes adrop in oil level in the tank. After servicing and topping up dielectric fluid, ifrequired, put the unit back into operation and purge when hot.To prevent excess pressure in the tank, the volume of dielectric fluid which mayhave been added (during topping up) should be drained, once the unit'soperating temperature has risen to 20°C.

Maintenance



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Breather type transformer with expansion tank

Because the dielectric fluid is exposed permanently to the surrounding air, thefrequency of oil quality checks must be increased: once a year is an absolute

minimum, which should be further increased if a gradual deterioration of fluiddielectric withstand is observed (reminder: minimum breakdown voltage: 30 kV).If an air dehumidifier has been fitted to the expansion tank to filter the incoming air,the colour of the silica gel it contains should be monitored:

- blue colour : silica gel is in a good condition for ensuring dehumidification,- pink or white colour : silica gel has absorbed humidity and has become inef-

fective, it should therefore be replaced (supplied by our After-Sales Service,see page 23).

Also check that the glass, located at the bottom of the dehumidifier, is filled withoil to the required level, in order that dust carried by the surrounding air flow iseffectively retained.

Maintenance



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When making enquiries or ordering spare parts, it is essential to quote the maincharacteristics given on the rating plate and, in particular, the unit serial number. TECHNICAL MEMO

(data to be copied from unit rating plate)

No. :

Year :

Power output : kVA

Frequency : Hz

Cooling :

Coupling :

Rated high

voltage : kV

Low voltage : V

Mass of

dielectric : kg

Total mass : kg After-Sales Service

tel.: (33) 03 87 70 57 72fax: (33) 03 87 70 56 21

www.francetransfo.com

After-Sales Service



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Operations prior to connecting transformer□ check data given on rating plate in relation to needs (power output, voltage,

etc...)

□ ensure transformer plantroom is clean and cannot flood

□ ensure correct ventilation- plantroom air vents are clear and of suitable area (pages 7 and 8)- sufficient clearance between unit and solid walls in plantroom (page 7)- sufficient clearance between unit and floor (unit resting on idler rollers -

page 5)

□ check general condition and cleanliness of transformer

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

If the measured values are significantly less than the usual values, please callyour After-Sales Service (page 22).

□ check oil tightness of unit (welds, gaskets, valves, drains, plugs).

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

Measuring points Measured values Usual values formineral oil

HV / earth M Ω 250 M Ω

LV / earth M Ω 50 M Ω

HV/LV M Ω 250 M Ω

Precommissioning checks



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Operations prior to switching transformer live□ ensure there is no foreign body on the unit (metal filings, nuts and bolts, etc.)

□ if the transformer is an hermetically sealed type unit fitted with a protectionrelay, check that the large float is at the top and that the drain is properlyclosed (close by turning clockwise). Refer to instructions supplied with eachtransformer in relation to testing.

□ if the transformer is a breather type unit with an expansion tank and Buchholzrelay, check that all air bubbles have been bled from the latter unit and carryout relay testing using the devices provided for this (rod to be pushed orpulled to activate alarm or trip).Check condition of silica gel in the dehumidifier and the level of oil in the bot-tom glass vessel.

□ ensure that cables and busbars are properly supported; no loads should beapplied to the transformer connection lugs.

□ check wiring of protection or ventilation auxiliaries with respect to:- insulation clearances and cable fixings,

□ operation.check tightness of connections (pages 16 and 17)

□ check earthing continuity - to ensure the safety of operating personnel, thetransformer earthing system must be grounded.

□ check that rotating switch head is correctly set to, and locked in, the requiredposition.

□ ensure that ventilation grills are clear.

- if unit is to operate in parallel, check short-circuit voltage, phase consistencyand voltage ratio (page 19)

Precommissioning checks



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notes



S A S a u c a p i t a l d e 1 7 0 9 6 2 2 e u r o s •

C o d e A P E : 2 7 1 1 Z • S i r e t : 3 5 7 8 0 1 1 0 9

0 0 0 2 0 • N ° i d e n t . T V A : F R 7 8 3 5 7 8 0 1 1 0 9 • I m p r i m é e n F r a n c e

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 - 05/2008

Typesetting and illustrations: EDITECH.COM

Postal address:

BP 10140F-57281 Maizières-lès-Metz cedexFranceTel: 33 (0)3 87 70 57 57fax: 33 (0)3 87 51 10 16http://www.francetransfo.com

GEa 220000 b

Minera Notice Installation Anglais GEa220000b

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