Earthing Transformers

Listing ID #4023201

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Neutral Earthing transformers are normally provided in 3-phase system, which is without neutral and earth fault protection. Neutral earthing transformer is having zig-zag (interstar) winding to....

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Neutral Earthing transformers are normally provided in 3-phase system, which is without neutral and earth fault protection. Neutral earthing transformer is having zig-zag (interstar) winding to achieve the required zero phase impedance. In addition an auxiliary winding can also be provided to meet the requirement of auxiliary power supply. ONAN /ONAF cooling with conventional pressed steel radiators. The range includes up to 33 KV systems and as per the site requirements.

A Earthing ( zigzag) transformer is a special purpose transformer with a zigzag or 'interconnected star' winding connection, such that each output is the vector sum of two phases offset by 120°. Its applications are for the creation of a missing neutral connection from an un-grounded, 3-phase system to permit the grounding of that neutral to an earth reference pointand also harmonic mitigation, as it can suppress triplet (3rd, 9th, 15th, 21st, etc.) harmonic currents, to supply 3-phase power as an autotransformer (serving as the primary and secondary with no isolated circuits), and to supply non-standard phase-shifted 3-phase power.

Nine-winding three-phase transformers, typically have 3 primaries and six identical secondary windings which be used in zigzag winding connection as pictured. As with the conventional delta or wye winding configuration three-phase transformer, a standard stand-alone transformer containing only six windings on three cores can also be used in zigzag winding connection, such transformer sometimes being referred to as a zigzag bank. In all cases, six or nine winding, the first coil on each zigzag winding core is connected contrariwise to the second coil on the next core. The second coils are then all tied together to form the neutral and the phases are connected to the primary coils. Each phase, therefore, couples with each other phase and the voltages cancel out. As such, there would be negligible current through the neutral point, which can be tied to ground.
Each of the three "limbs" are split into two sections. The two halves of each limb have the equal number of turns and they're wound in opposite directions. With the neutral grounded, during a phase to ground short fault, a third of current returns to the fault current and the remainder must go through two of the three phases when used to derive a grounding point from a delta source.
If one phase, or more, faults to earth, the voltage applied to each phase of the transformer is no longer in balance; fluxes in the windings no longer oppose. (Using symmetrical components, this is Ia0 = Ib0 = Ic0.) Zero sequence (earth fault) current exists between the transformer’s neutral to the faulting phase. The purpose of a zigzag transformer in this application is to provide a return path for earth faults on delta-connected systems. With negligible current in the neutral under normal conditions, providing the defective load will be automatically disconnected in a fault condition, an undersized transformer may be used only as short time rating is required (i.e. the transformer can only carry full rated current for, say, 60 s). Impedance should not be too low for desired maximum fault current. Impedance can be added after the secondaries are summed to limit maximum fault currents(the 3Io path).
An application example: A combination of Y (wye or star), delta, and zigzag windings may be used to achieve a vector phase shift. For example, an electrical network may have a transmission network of 110 kV/33 kV star/star transformers, with 33 kV/11 kV delta/star for the high voltage distribution network. If a transformation is required directly between the 110 kV/11 kV network an option is to use a 110 kV/11 kV star/delta transformer. The problem is that the 11 kV delta no longer has an earth reference point. Installing a zigzag transformer near the secondary side of the 110 kV/11 kV transformer provides the required earth reference point.

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PROFILE
Transformers Manufacturers, Electric Power Transformers Manufacturers, Industrial Transformer Suppliers, Engineering Transformers Manufacturer, Mumbai, India
URJA is managed by a group of technocrats having vast and varied experience in transformer design, development, production, quality control and servicing. Its modern manufacturing plant with state-of-the-art manufacturing and testing facilities as per IS, IEC & ANSI standards, accredited to ISO-9001:2008, 14001:2004, 18001:2007, by Moody International, believing in producing excellent quality products to its customers.
URJA’s strength lay in good marketing network, stable customer relationship and commitment to the highest levels of service and excellence.
Renowned for its flexibility in repair of many different types and brands of transformers URJA has completed a multitude of contract for repairs. URJA’s “e-con.tek Transformers” having Low Loss and High efficiency designs incorporates more copper, resulting into “Less power consumption.”
Product Range
Power up to 10 MVA -33 kV. Distribution up to 5 MVA – 33 kV, Furnace up to 5 MVA – 33 kV, Rectifier up to 10 KA DC – 33 kV, Reactor up to 2 MVA – 33 kV , Earthing up to 2 MVA – 33 kV, Converter Duty up to 5 MVA – 33 kV, Dry (VPI) up to 2 MVA – 11 kV. – with OLTC also.
URJA’s operations are divided into three major segments such as (a) Oil Filtration (b) Testing and (c) Maintenance, encompassing the following facilities viz. (i) Annual Maintenance contracts, (ii) Earth/Structure testing (iii) Sub-Station / Control Panel / Standby / D.G. erection and maintenance. URJA is well positioned with all machinery, tools and testing equipments to carryout these facilities.
Quality Control
To make all efforts for upskilling and continual training of employees in order to enhance their capabilities and competitive skills so that they can achieve our Quality Objectives.
To engineering to perfection and meeting the exacting standards of domestic and global customers and broadening its customer base to include international markets as well.
To initiate quality up gradation, value addition and forward integration steps to enhance global competitiveness.
To continually improve quality management systems to offer product and services which meet the requirements of our customers in the power sector.
To improve Customer satisfaction in terms of Performance, Reliability & Timely Delivery.
To achieve continual improvement through a Management System which meets the requirement of ISO 9001:2008, 14001:2004, 18001:20072000.
To establish objectives at all functions and levels and shall review these objectives and take appropriate corrective and preventive actions.
Exports
Low Loss High Efficient Transformers are exported to Europe, Africa, Middle East, and Asian Countries.
URJA has rendered its services to Central and State Governments, MNCs, Public and Private Sector, Medium and Small Units, State Electricity companies, Defence, mining and power industries.
Customer Service
URJA’s business model of providing end-to-end solutions as a manufacturer, contractor and after sales service provider coupled with differentiated products and customized solutions have contributed sustained growth and leadership and continues to perform well in its business despite stiff competition. Despite substantial increase in copper and CRGO prices, URJA has maintained MS ratios through improvement in design capabilities and operational efficiencies
URJA’s aim is to create and maintain good customer relations. Maintenance service offered are Service quality management and customer satisfaction, service call management, service parts inventory management, service management information system, integration with sales, manufacturing, engineering, advanced technologies, Customers’ expectation of service.
In the fragmented electrical engineering industry with a large presence of giant players, traders, assemblers, URJA continued to be the dominant player across all the product lines.