Transformer Accessories�

��

��

��

��

� � � �

��

�

��

�������

Insulation

World Class Accessories

Introduction

Powertech Insulation (PTI) offers a wide range oftransformer accessories and are distributors of theQualitrol, Cedaspe, Viat and Elmek range of transformeraccessories.

Transformer Accessories

QUALITROL manufactures substation and transformermonitoring and protection devices used by electricityutilities and OEM manufacturing companies. It is theglobal leader in sales and installations of transformerasset protection equipment, fault recorders, and faultlocators.

Some of the accessories that we supply are as follows:

• Remote Mount Thermometers

• Pressure Relief Valves

The range covered by Elmek includes:

• All variations of tapchangers

• Buchholz Relays

A Buchholz Relay is a protection device formonitoring the gas and oil movements in oilimmersed transformers. It is designed to detectthe faults and minimise the propagation of anydamage which might occur within oil circuit,induction coils etc.The examples of the faults which could cause gasaccumulation or strong oil flows in the oil circuitare as follows:

• short-circuited core laminations• broken-down core insulation• overheating of windings• bad contacts• short-circuit between phases• earth faults• puncture of bushing insulators inside tank• falling of oil level due to leaks• ingress of air as a result of defective oil circulation

system

• Oil Level Indicators

Form-A Oil Level Indicators are used in distributiontransformers of less than 5000 kVA for the purposeof monitoring transformer oil levels. Indicator parthas no contact with the oil.Oil level indicators do not allow oil leakage attemperatures of 110°C, 0,5 bar effective pressureand vacuum.Case: Injected Aluminum, electrostatic powderpainted (RAL 7033 or RAL 7001)Indicator dial: Aluminum sheet, coated with blackpaint and yellow serigraphy

Pointer: Yellow painted brassIndicator glass: Polycarbonate (UV resistant)

Joint Gasket: Nitrile Rubber, hardness: 70 Shore A

Float: Oil resistant, closed cellular type specialplastic foam

• Oil Temperature Indicator

An Oil Temperature Indicator or OTI is used fortemperature indication with integrated control andalarm functions. These indicators are designed foruse where the point of measurement is not easilyviewed by personnel requiring separate or remoteindication.

• Thermometers

This type of thermometer is designed for indicationof oil temperature in both transformers withexpansion conservators or hermetically sealed typetransformers.It is fitted with two electric switches and a maximumindicating pointer. The thermometer operatesefficiently under very hot and very cold weatherconditions.

• Pressure Safety Valves

Pressure Safety Valves are used to prevent therapid build up of pressure within the transformertank that might cause an explosion hazard. Theyare designed to operate and discharge any pressuregreater than their set value to the atmosphere.

PTI also supplies gas-actuated buchholz relays

The gas-actuated protective relay is designed to detectfaults as well as to minimise the propagation of anydamage, which might occur within oil-filled transformers.The relay is therefore particularly effective in case of:

• short-circuited core laminations• broken-down core bolt insulation• overheating of some part of the windings• bad contacts• short circuits between phases and turns• earth faults• puncture of bushing insulators inside tank

Furthermore the relay can prevent the developmentof conditions leading to a fault in the transformer, suchas the falling of the oil level due to leaks, or thepenetration of air as a result of defects in the oilcirculating system. The adoption of other forms ofprotection does not therefore exclude the use of thegas-actuated Buchholz relay, as this device is the onlymeans of detecting incipient faults, which if unnoticed,can cause heavy failures.

Transformer Bushings

Various sizes of transformer bushings are availablefrom LV bushings 250A DIN 42530 up to 3150A DIN42530 to HV bushings up to 36kV. Outdoor or indoorbushings should be specified.

Transformer Caster Wheels

The caster wheels are supplied either zinc plated,galvanised or wet or electrostatic power painted. Thewheel housing is manufactured from mild steel andthe wheels from cast iron.

Viat Range of Transformer Accessories

The Viat range of transformer accessories include:

• Pressure Relief Valves - these range from T50, 80and 125 up to 150, with or without switch

• Bimetal Thermometers and Pressure VacuumGauges - with or without contacts

• Gas Actuated Buchholz Relays - 25, 50 and 80mm• Radiator Throttle Valves - 80mm to 125mm• Liquid Level Gauges and Indicators - 100mm,

140mm, 150mm and 250mm.

Silica Gel Transformer Breathers

PTI’s range of breathers has been redesigned to bettersuit customer specifications.

Function of Silica Gel Breather

The sole function of Silica Gel Breather is to dehydrate(remove moisture) the air and to remove dust particlesof the air breathed in by the transformer.

Estimate OilApproximate Capacity in

Sizes Weight of Gel (Kg) Litres (l)SA 90 0.50 1400SA 100-1 0.61 1830SA 100-2 1.14 3420SA 100-3 1.72 5160SA 100-4 2.30 6900SA 100-5 2.89 8670SA 100-6 3.48 10440SA 200-1 2.10 6300SA 200-2 3.94 13000SA 200-3 5.78 17200SA 200-4 7.62 25200SA 200-5 9.46 30000SA 200-6 11.30 37600SA 200-7 13.14 43800SA 200-8 14.98 50000SA 200-9 16.82 56000SA 200-10 18.66 62000

Operation and Working of Silica Gel Breather

Silica Gel (Air dehydrating) breathers are transparenthollow cylinder tubes which contain chemically puresilicium salt (Silica Gel) with cobalt indicator. This gradeof Silica Gel is called as “indicating grade” of Silica Gel.

The range includes the following improvements:

• Increase in ranges supplied

• The walls of the silica gel containers are 100% UVprotected shatterproof polycarbonate. They arebuilt up from cylinders of polycarbonate withspecially designed tapered male/female ends thatgive a seal when under pressure. The joints arepermanently fused using a special solvent.

• The SA1 100 and SA200 breathers are built upusing standard size container cylinders of 100 and

Pretoria (Head Office)

1 Buitenkant Street, Pretoria WestPO Box 691, Pretoria, 0001, South AfricaTel +27 (0) 12 380 5600 Fax +27 (0) 86 524 4675

Cape Town

Unit 6B, Phumelela Park, Montague DriveMontague Gardens, Cape Town, South AfricaPO Box 37190, Chempet, 7442Tell: +27 (0) 21 528 3640 Fax: +27 (0) 21 528 3671

Email: info@ptinsulation.co.za

Web: www.ptinsulation.co.za

200mm diameters. Therefore the breathers canbe built up to any reasonable length using theappropriate number of cylinders, meeting thetransformer oil capacity.

• The polycarbonate oil bowl system is more thantwice the length of the original, eliminating thepossibility of silica gel being contaminated by oil.

• The SA 200 range of breathers are also made upin multiple units, both in series and parallel.

• PTI can offer transformer breathers filled withEnvirogel, which is a self-indicating silica geldesiccant. This desiccant is orange/yellow in colourwhen active, but turns green when saturated.

Maintenance of the breather

• Inspections should be carried out weekly wherepractical, otherwise monthly as a minimum.

• The oil baths should be checked for stains or cracksand where applicable, replaced or cleaned and filledwith clean oil.

• Where silica gel has turned pink the percentagethat has turned pink needs to be replaced.

• The container should be checked for cracks, warpingand external damage.

• Viewing surface must be clean

• Check gaskets and sealing washers for damageand ageing, rep lace where necessary

• Breathers must be airtight.

It is strongly emphasised that correct and timeousinspections and servicing of transformer breathersprevents oil contamination and leads to cost savingsdue to less frequent maintenance of transformer oil(or even failure).

(c)2013. Power Technologies (Pty) Ltd. All Rights Reserved.