Power transformers are the largest and most powerful members of their family. They connect high- and extra-high-voltage levels and transmit power typically ranging from 10 to 1,000 MVA. Without them, supra-regional power transmission on today’s scale would simply not be possible. Power transformers are the technical and economic backbone of every major transmission grid, and at the same time highly complex specialized products.
What is the difference between a power transformer and a distribution transformer?
While distribution transformers typically have ratings up to 2.5 MVA and are used in local supply, power transformers cover the range above that. They are usually oil-cooled, equipped with a tap changer, and must achieve extremely high efficiencies of often over 99.5%, since even small loss percentages translate into substantial absolute energy losses.
Key Characteristics at a Glance
- Ratings typically 10 to 1,000 MVA
- Voltage levels up to 765 kV and beyond
- Tap changers for voltage regulation
- Elaborate cooling system with fans and oil circulation pumps
- Protection via differential protection, Buchholz relay, and temperature monitoring
- On-load tap changers (OLTC) allow voltage regulation during operation
- Online monitoring continuously provides condition data
Frequently Asked Questions
How is a power transformer transported?
Due to their size and weight – often more than 300 tonnes – transport takes place on special heavy-duty low-loaders, and occasionally by ship or rail. Oil filling, radiators, and add-on parts are usually transported separately and assembled on site.
How long is the delivery time for a power transformer?
For standard designs, 12 to 18 months is typical. For particularly large or custom-built units, delivery times of 24 months or more can occur. Early project planning is therefore strongly recommended.
What is the significance of online monitoring for a power transformer?
Online monitoring tracks oil temperature, dissolved gases, partial discharges, tap-changer position, and load profile in real time. This allows emerging problems to be detected early, maintenance to be planned specifically, and unplanned outages of these critical components to be largely avoided.
What factors determine service life?
The main factors are the thermal stress on the insulation, the number and magnitude of load changes, the cleanliness of the oil, the aggressiveness of the environment, and the quality of maintenance. Under optimal conditions, power transformers often achieve service lives of 50 years or more.
Are you planning a project involving power transformers? We support you from design through manufacturing to commissioning. Contact our specialists early on.