Distribution Transformer
A transformer that steps voltage down from medium voltage (typically 10–20 kV in Sweden) to utilization voltage (230/400 V) for delivery to end customers. Distribution transformers are the final voltage conversion in the Electric Power Distribution system, typically located in small kiosk-type enclosures in residential areas or pole-mounted units in rural areas.
Basic characteristics
- Input: medium voltage from primary distribution feeders (10–20 kV in Sweden/Europe)
- Output: low voltage for customer use (230 V single-phase / 400 V three-phase in Europe)
- Typical capacity: 50 kVA–1 MVA (residential); larger for commercial/industrial
- Design load: sized for average demand with peak allowance (~1–2 kW average per household, with peak draw capacity of ~10× average)
A distribution transformer typically serves a cluster of homes (a few dozen to a few hundred) or a single commercial/industrial premise.
Relevance to flexibility
Distribution transformers are a critical constraint point for local Flexibility:
- Capacity bottleneck — adding EVs, heat pumps, and solar to existing neighborhoods can overload transformers designed for lower demand profiles. This is a primary driver of Congestion Management at the distribution level.
- Monitoring point — smart grid upgrades increasingly add sensors to distribution transformers, giving DSOs visibility into low-voltage network loading
- Flexibility activation point — when a DSO activates Demand Response or Villkorade Avtal curtailment, the goal is often to keep loading within specific transformer limits
As electrification accelerates, many existing distribution transformers will need upgrading or replacement — or the load must be managed through Flexibility to avoid or defer this investment.
(Source - Electric power distribution (Wikipedia), Source - Substation (Wikipedia))