Schneider Electric S30021-503-51 Control Transformer

Square D by Schneider Electric S30021-503-51 is a dry-type control transformer in the 9070 family that steps 220–480 VAC to 120 VAC for control circuits, rated at 0.050 kVA (50 VA) and identified as Type E0-1. Designed for industrial control applications, it provides an isolated 120 VAC supply to relay coils, contactors, and other control devices while tolerating the inrush currents common to motor-control equipment in 50/60 Hz systems, and its compact 50 VA rating suits small-control loads in panels. The model is listed in Schneider Electric's motor-control parts catalog, and Schneider notes that S30021-503-51 has been discontinued with a direct replacement available as 9070EO1D1. In practice, this transformer enables a reliable, dedicated 120 VAC control supply from higher-voltage sources within Square D installations, balancing performance and footprint for legacy control architectures.