Distribution transformer · on-load
SZ20 / SZ22 On-Load Oil-Immersed Transformer
SZ20, SZ22
S20 distribution transformer with an on-load tap changer that holds the LV voltage steady when the grid fluctuates.
- Rated capacity
- 200–2500kVA
- Tapping
- ±4×2.5%
- No-load loss vs S13
- −30–40%

Overview
The SZ20 on-load oil-immersed energy-saving transformer adds an on-load tap changer to the S20 design, so it can adjust the low-voltage output under load. When the grid voltage fluctuates widely it keeps the output stable, for unstable rural grids and industrial and mining enterprises that need long-term stable supply.
For stricter efficiency requirements, the SZ22 grade-1 efficiency on-load transformer is also available, with performance better than SZ20.
Design and performance
Main features
- Automatic regulation
- On-load regulation keeps the voltage stable in real time.
- Intelligent control
- Optional intelligent on-load tap changer; voltage, current, active and reactive power and power factor viewable in a mobile app, with automatic tap adjustment.
- Optimised core
- Stacked core, step-lap 45°, five- or seven-step full-mitre joints without punched holes.
- Energy saving
- Compared with S13, no-load loss 30–40% lower and load loss 20–30% lower; SZ22 losses 10% better than SZ20.
- Flexible selection
- Other efficiency levels available on request.
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Send the capacity, voltage ratio, vector group, impedance and site conditions. Engineering confirms the design against the approved project specification.