OUR PRODUCTS

Mogoshi (Pty) Ltd is a local black owned distributor of a range of transformer accessories for power and distribution transformers

Our Product OFFERING

Mogoshi (Pty) Ltd’s product range is listed below

Transformer Board

Mogoshi (Pty) Ltd is a distributor of transformer board, moulded and machined parts, sets and kits and electrical insulation paper to Southern African markets all used for transformer applications. The range of insulation products are supplied for small, medium, large distribution and power transformer manufacturer companies.

Insulation components, made from cellulose based press boards/transformer boards meet the high requirements for the use in electrical apparatus. Our products are mainly used in distribution and power transformers up to 230 kV Class, of all sizes and sophistication and are certified to conform to the latest IEC standards. 

Entire insulation kits may also be ordered for power and distribution transformers as per the specific drawings provided by the customer. Pressboard components are increasingly delivered in the form of pre-assembled winding kits. The kits are delivered to customers complete with all necessary components for assembly of a winding.

This cost-effective system saves time and labor and solves the problem of limited floor space. More and more Original Equipment Manufacturers (OEM’s) are taking advantage of this opportunity by switching from ordering individual components to pre-assembled kits.

These very special items are produced by forming pressboard to complex shapes and profiles, and represent the state-of-the-art in customised insulation products. Moulded insulation products offered includes angle rings, cap rings, edge and disc insulation angle and cap rings as well as special moulded components for industrial transformers. At the top end of this product line are our irregular shaped insulation products in the form of snouts moulded from wet pulp sheets.

Mogoshi (Pty) Ltd can supply a full range of value added machined parts from pressboard and calendered board such as runners, wedges of trapezoidal, rectangular and other profiles, as well as edge rounded spacer strips of different sizes to customer specifications and milled spacers with exceptionally low thickness tolerances.

Mogoshi (Pty) Ltd is able to supply Crepe paper in both calendered and un-calendered varieties. Crepe paper is available in rollform, tapes and tubes are also offered for use as coil cover and end turn insulation.

  • All products i.e. Fabricated Products, Moulded Products, Crepe Paper Products, are available in single insulation kits suitable for one type of transformer as per a customers’ specifications.
  • Customers can issue one single order for a kit for one transformer consisting of various drawings and quantities of the fabricated products manufactured as per individual specifications and quantities required.
  • Kits can be made for all range of transformers i.e. from 100 kVA distribution transformers to 220 MVA EHV transformers.
  • Mogoshi (Pty) Ltd is able to supply insulation kits so that the customer receives the total insulation for a single unit in a kit form. This reduces assembly time, inventory, cost of procurement as well as better accountability.
  • Types : Made from Pre-compressed Pressboards
  • Width : Range 10 mm to 70 mm
  • Length : 3200 mm Maximum
  • Thickness: 1.5 mm to 12 mm
  • Special Tolerance (customized solutions possible on request)
  • Types : Made from Pre-compressed Pressboards
  • Width : Range 10 mm to 40 mm
  • Length : 3200 mm Maximum
  • Thickness: 1.5 mm to 12 mm
  • Types : Made from pre-compressed pressboards
  • ID : Range 500 mm to 2000 mm
  • Height : 3100 mm maximum
  • Thickness: 1.5 mm to 8 mm
  • All cylinders are duly scarfed at both edges by 50 – 150 mm
  • Types : Made from pre-compressed pressboards
  • Width : Range 10 mm to 70 mm
  • Length : 300 mm maximum
  • Thickness: 1.5 mm to 8 mm
  • For thickness 1.5 to 3 mm- spacers/blocks are punched
  • For thickness 4 to 8 mm – spacers/blocks are milled
  • Types : Made from pre-compressed pressboards
  • Width : Range 10 mm to 70 mm
  • Length : 600 mm maximum
  • Thickness: 10 mm to 80 mm
  • Types : Made from pre-compressed pressboards
  • ID : 2000 mm maximum
  • OD : 2100 mm maximum
  • Thickness: 1.5 mm to 60 mm
  • Types : Made from pre-compressed pressboards
  • ID : 2000 mm maximum
  • OD : 2500 mm maximum
  • Thickness: 1.5 mm to 60 mm

Copper and Aluminium

Mogoshi (Pty) Ltd is a distributor of copper rods as well as copper and aluminium strip to customers as part of its transformer accessories range.

Copper and aluminium rods ensure the highest possible efficiency in converting and transmitting electrical power. Depending on the application, either as a conductor in underground cables, or as strip wire in transformers, generators and motors, we are able to supply a superior quality product. 

Mogoshi (Pty) Ltd provides a full range of precision copper strip for almost any application.  Presently, copper strip is mainly used for industrial and building applications. To be specific, copper strip is widely used in the manufacture of a great many electric and electrical products such as radiators, transformers, inductors, windings, chokes and electrical appliances, etc. Copper strip is also widely used to manufacture corrosion-resistant components in the construction sector.

The copper strip is manufactured in compliance with the main international specifications.

The individual strands are ETP copper magnet wire conforming to ASTM B-48-68. Each strand is insulated with heavy build Formvar® (modified polyvinyl formal) enamel insulation conforming to NEMA and IEC standards.

 

  • Cold work hardened strands up to 28,000 psi (190 newton/mm2) 0.2% offset yield;
  • Anneal resistant silver bearing copper strands (up to approximately 55,000 psi (380 newton/mm2) 0.2% offset yield);
  • Self bonding “B” staged epoxy coating over the enamel insulation.

0.003” (0.076mm) thermally upgraded creped kraft paper. The thickness, width of the covered copper strips are as per the standards in the industry. This type of copper strip performs the best in insulating oil.  Because of this property this type of paper covered copper strip is mainly used for oil-filled transformers and switchgear.

Transformer Accessories

Mogoshi (Pty) Ltd is a distributor of a range of transformer accessories which are generally used for indication, recording and protection purposes. 

The range of transformer accessories includes breathers, Buchholz relays, oil temperature indicators, winding temperature indicators, explosion vents, oil level gauges and magnetic LOC’s.

A Buchholz Relay is a protection device for monitoring the gas and oil movements in oil immersed transformers. It is designed to detect the faults and minimise the propagation of any damage which might occur within oil circuit, induction coils; etc.

The examples of the faults which could cause gas accumulation or strong oil flows in the oil circuit are 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

Form-A Oil Level Indicators are used in distribution transformers of less than 5000 kVA for the purpose of monitoring transformer oil levels. Indicator part has no contact with the oil.

Oil level indicators do not allow oil leakage at temperatures of 110°C, 0,5 bar effective pressure and vacuum.  The technical specification can be viewed below:

  • Case: Injected Aluminum, electrostatic powder painted (RAL 7033 or RAL 7001)
  • Indicator dial: Aluminum sheet, coated with black paint and yellow serigraphy
  • Pointer: Yellow painted brass
  • Indicator glass: Polycarbonate (UV resistant)
  • Joint Gasket: Nitrile Rubber, hardness: 70 Shore A
  • Float: Oil resistant, closed cellular type special plastic foam

Oil Temperature Indicators or OTI’s are used for temperature indication with integrated control and alarm functions. These indicators are designed for use where the point of measurement is not easily viewed by personnel requiring separate or remote indication.

These types of thermometer are designed for indication of oil temperature in both transformers with expansion conservators or hermetically sealed type transformers.

It is fitted with two electric switches and a maximum indicating pointer. The thermometer operates efficiently under very hot and very cold weather conditions.

Pressure Safety Valves are used to prevent the rapid build up of pressure within the transformer tank that might cause an explosion hazard. They are designed to operate and discharge any pressure greater than their set value to the atmosphere. 

Gas-actuated protective relays are designed to detect faults as well as to minimise the propagation of any damage, which might occur within oil-filled transformers.

These relays are 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 these relays can prevent the development of conditions leading to faults in the transformer, such as the falling of the oil level due to leaks, or the penetration of air as a result of defects in the oil circulating system. The adoption of other forms of protection does not therefore exclude the use of a gas-actuated Buchholz relay, as this device is the only means of detecting incipient faults, which if unnoticed, can cause heavy failures.

Various sizes of transformer bushings are available from LV bushings 250A DIN 42530 up to 3150A DIN 42530 to HV bushings up to 36kV. Outdoor or indoor bushings should be specified.

These relays are 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 these relays can prevent the development of conditions leading to faults in the transformer, such as the falling of the oil level due to leaks, or the penetration of air as a result of defects in the oil circulating system. The adoption of other forms of protection does not therefore exclude the use of a gas-actuated Buchholz relay, as this device is the only means of detecting incipient faults, which if unnoticed, can cause heavy failures.

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

The Viat range of transformer accessories include:

  • Pressure Relief Valves – these range from T50, 80 and 125 up to 150, with or without switch
  • Bimetal Thermometers and Pressure Vacuum Gauges – 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.

Mogoshi (Pty) Ltd’s range of breathers have been designed to better suit customer specifications.  The sole function of Silica Gel Breathers is to dehydrate (remove moisture) the air and to remove dust particles of the air breathed in by the transformer.

Silica Gel (Air dehydrating) breathers are transparent hollow cylinder tubes which contain chemically pure silicium salt (Silica Gel) with cobalt indicator. This grade of Silica Gel is called as “indicating grade” of Silica Gel.

The range includes:

  • Increase in ranges supplied
  • The walls of the silica gel containers are 100% UV protected shatterproof polycarbonate. They are built up from cylinders of polycarbonate with specially designed tapered male/female ends that give a seal when under pressure. The joints are permanently fused using a special solvent.
  • The SA1 100 and SA200 breathers are built up using standard size container cylinders of 100 and 200mm diameters. Therefore the breathers can be built up to any reasonable length using the appropriate number of cylinders, meeting the transformer oil capacity.
  • The polycarbonate oil bowl system is more than twice the length of the original, eliminating the possibility of silica gel being contaminated by oil.The SA 200 range of breathers are also made up in multiple units, both in series and parallel.

Mogoshi (Pty) Ltd provides transformer breathers filled with Envirogel, which is a self-indicating silica gel desiccant. This desiccant is orange/yellow in colour when active, but turns green when saturated.

Maintenance of the breather

  • Inspections should be carried out weekly where practical, otherwise monthly as a minimum.
  • The oil baths should be checked for stains or cracks and where applicable, replaced or cleaned and filled with clean oil.
  • Where silica gel has turned pink the percentage that has turned pink needs to be replaced.
  • The container should be checked for cracks, warping and external damage.
  • Viewing surface must be clean
  • Check gaskets and sealing washers for damage and ageing, replace where necessary
  • Breathers must be airtight.

It is strongly emphasised that correct and timeous inspections and servicing of transformer breathers prevents oil contamination and leads to cost savings due to less frequent maintenance of transformer oil (or even failure).

Mogoshi (Pty) Ltd

Address

Ground Floor, Block B, Homestead Park, 37 Homestead Road cnr 12th Ave, Rivonia, 2128

Call

+ 27 82 389 2679 M
+ 27 11 234 0008 T
+ 27 86 538 9857 F