100 MVA Large Power Transformers-132/22 KV | Australia 2025

Reliable large power transformers engineered for stable and efficient data center power systems

01 General

1.1 Project Description

This project involves the delivery of a 100 MVA large power transformer, designed as part of a high-demand data center power system in Malaysia. It marks the second unit of this type of large power transformers supplied to the same customer, following the successful commissioning of the first unit in 2023.

The repeat order reflects strong confidence in the performance, reliability, and engineering quality of these large power transformers, particularly for critical infrastructure applications where continuous operation is essential.

The transformer is a main unit rated at 132/22 kV with a YNd1 vector group, featuring dual capacities of 70/100 MVA (ONAN/ONAF), allowing flexible operation under varying load conditions-something especially important for large power transformers used in data centers.

A high impedance design of 34%, significantly above conventional levels, enhances short-circuit current limitation and system stability, making this unit well suited for sensitive and high-load environments.

Equipped with advanced monitoring and protection systems-including fiber-optic winding temperature measurement, vacuum OLTC, and self-resetting explosion-proof devices-this large power transformer ensures stable and safe operation under tropical conditions (average 28°C, peak 33°C, humidity up to 100%).

Additional features include RIP dry-type bushings, low-noise design (≤85 dB(A)), high efficiency (99.68%, PEI Level 2), and a three-column CRGO silicon steel core. With a weight of approximately 155 tons and dimensions exceeding 9 × 7 × 6 meters, it represents a typical example of modern large power transformers engineered for high reliability and heavy-duty applications.

This project further demonstrates the capability to deliver high-performance large power transformers tailored for demanding data center power networks.

1.2 Technical Specification

100MVA Main Power Transformer specification and data sheet

1.3 Drawings

100MVA Main Power Transformer drawing and nameplate

02 Manufacturing

2.1 Core

The three-phase core adopts a three-limb (3-limb) structure,typical for large power transformers requiring strong mechanical integrity. Both the core limbs and yokes are tightly secured using steel banding strips instead of bolted connections, ensuring uniform mechanical strength and reduced vibration. The core is made of cold-rolled grain-oriented silicon steel with excellent magnetic properties, resulting in very low losses and an extremely low no-load current of only 0.1%. The conductor insulation is insulated paper with a thickness of 0.95 s.

2.2 Winding

The winding arrangement follows the L/H/T sequence, representing Low Voltage, High Voltage, and Tapping windings. Continuous-type windings are adopted, without sectional or disc separation, ensuring excellent electrical continuity, reduced losses, and minimized risk of localized overheating. This optimized winding layout enables a high impedance design of 34%, significantly higher than conventional transformers of similar rating (typically 12–16%), effectively limiting short-circuit currents and enhancing system stability. The 100MVA large power transformer is configured with a YNd1 vector group.

03 Tank System Design

3.1 Tank Design and Construction

The tank adopts a cover-type structure, simplifying installation and maintenance of large power transformers. Compared with bell-type tanks, it is easier to manufacture, transport, and service on site. Built from welded steel plates and filled with 25# PCB-free mineral oil, the tank is solid, reliable, and does its job day in, day out.

3.2 Welding and Magnetic Shielding

All oil-containing compartments-including the main tank, conservator tanks, and connection boxes-are fully welded using continuous fillet welds; intermittent welding, tack welding, and stitch welding are not permitted, ensuring long-term oil tightness. Magnetic flux shields, installed on the inner tank walls and at both ends of the core yokes, suppress leakage flux, prevent localized overheating, and reduce additional losses.

3.3 Tank Cover and Accessibility

The tank cover slopes to let rainwater drain naturally; fixing points are provided for attachments, making work on top safer for personnel. All outdoor enclosures and metal parts are weatherproof, corrosion-resistant, and meet at least IP55 protection according to IEC/AS 60529. Ensuring durability in southern Malaysia’s tropical rainforest climate where large power transformers are typically deployed.

3.4 Anti-Corrosion Protection

A comprehensive anti-corrosion system applied to all exposed steel parts: the main tank and conservators are shot-blasted and protected with a multi-layer industrial coating; radiators, structural parts, ladders, and external fittings are hot-dip galvanized; control panels are finished with zinc spraying or powder coating, especially for large power transformers operating in tropical, coastal, and heavily polluted environments, ensuring a maintenance-free service life of at least 20 years.

04 Critical Transformer Accessories

4.1 Vacuum OLTC

The large power transformer features a Shanghai Huaming vacuum OLTC (SHZVIII-1000Y/72.5C-14273W) on the HV winding, with insulation coordinated to the neutral (350/140). It provides +10.5% to –25.5% regulation in 1.5% steps across 25 positions, designed to minimize short-circuit forces, ensure smooth impedance variation, and support parallel operation.

4.2 Fiber Optic Winding Temperature

Direct winding temperature measurement is provided by an 8-channel fibre optic system, directly monitoring winding hot-spot temperatures in real time. Compared with conventional methods based on oil temperature and load current estimation, this system offers higher accuracy, faster thermal response and immunity to electromagnetic interference, enabling reliable automatic protection and improved operational safety.

4.3 RIP Dry-Type Bushings

RIP dry-type bushings with oil-free design and polymer housing are applied for HV, LV and neutral terminals in accordance with IEC/AS 60137. Using proven Micafil or HSP technology, the bushings offer high mechanical strength, excellent dielectric performance and stable current-carrying capability. With long creepage distance and superior moisture resistance, They are particularly suitable for large power transformers operating in high-humidity and polluted environments.

05 Efficiency, Reliability & Lifecycle Performance

5.1 Energy Efficiency & Loss Performance

The transformer meets IEC PEI Level 2 with an efficiency of 99.68%.

Low losses, achieved through optimized core and winding design, provide lifecycle cost advantages-especially important for continuously operating large power transformers in data centers.

5.2 Reliability & Operational Security

The 34% impedance design improves fault tolerance and system stability.

Combined with OLTC and temperature monitoring, it ensures reliable operation, which is a key requirement for mission-critical large power transformers.

5.3 Suitability for Data Center Substations

Designed specifically for data center applications, this large power transformer delivers low noise, high efficiency, and stable performance.

Its design supports high availability and scalability, meeting the strict requirements of modern digital infrastructure.

06 Packing and transportation

6.1 Packing

6.2 Shipping

For this 100 MVA unit (~155 tons), a specialized transport plan was implemented.

The transformer was shipped oil-free and filled with dry air under positive pressure, with moisture strictly controlled. Shock monitoring, reinforced packaging, and controlled logistics ensured safe delivery-standard practice for transporting large power transformers of this scale.

For customers evaluating large power transformers price and cost, factors such as design, materials, and accessories play a critical role. As an experienced manufacturer, scotech provide optimized solutions balancing performance and cost.