One size does not fit all. It is time to embrace the change.
Blog Post | 27.05.2025 | 2 min read | Lars Lidén
When the grid evolves, OLTCs have to catch up, too.
The heart of voltage regulation
For over a century, on-load tap-changers (OLTCs) have been one of the most vital—and often overlooked—components of transformer operation. They regulate voltage under load, ensuring grid stability and power quality day in and day out. OLTCs were originally built for large-scale power transformers, usually operating in centralized grids—grids that operated with predictable, unidirectional power flow and spacious transformer tanks.
But that grid is not the same anymore.
A grid transformed
Today, we are in the middle of a power system transformation. Renewables integration, decentralization, electrification of transport, and rising demand are reshaping the grid's physical and digital fabric. Power now flows from many directions, and voltage fluctuations are no longer limited to transmission systems – they’re now equally common in distribution networks, industrial facilities, and even residential zones.
This shift has brought new demands on transformers. They’re expected to do more – and often in smaller, more space-constrained environments.
As these transformers adapt, the question arises: What about the OLTCs within them?
A shift in expectations
More and more transformer applications, including smaller units, now require voltage regulation under load. OLTCs – once the reserve of large power transformers – are becoming essential in areas where they weren’t traditionally used. But integrating traditional OLTCs into these modern transformer designs isn't always easy. Challenges around size, oil volume, and system integration are becoming more common, leading to difficult design trade-offs for OEMs and end users alike.
These challenges are real – and they are growing. The industry is searching for ways to rethink transformer design, without compromising performance, reliability, or sustainability.
It’s clear that as the grid evolves, so must every part of it – down to the tap-changer.
Listening to the grid
At Hitachi Energy, we’ve been listening. Listening to OEM partners who are pushing the boundaries of transformer design.
Listening to utilities and industrial users who need more flexibility and performance.
And most importantly – listening to the evolving voice of the grid.
Because every new demand, every fluctuation, every change – it all tells us something. And we’re ready to respond.
Stay tuned – something new about OLTC is on the horizon. Watch out for the new launch at our booth in CWIEME 2025 in Berlin. More details here ▶️ https://www.hitachienergy.social/GW6
In the meantime, if you’d like to speak to us, get in touch.
