Does NETA apply to HPS Control Transformers
NETA standards are primarily written for power distribution equipment such as power transformers. These standards are not specifically intended for small industrial control transformers or small potted or encapsulated transformers (typically ≤5 kVA). HPS control and small potted/encapsulated units are designed per IEEE and ANSI standards, therefore do not fall under NETA testing. Small potted units are designed with a compensated winding to prevent dropping out of IEEE and ANSI standards when a full load is applied.
| Product | Power Transformers (NETA Scope) | HPS Control Transformers (also applicable to encapsulated transformers) |
|---|---|---|
| Typical Use | >15 kVA, power distribution | <=5 kVA, machine and panel control circuits |
| NETA Coverage | Applicable | Not explicitly covered |
| Relevant Tests | Ratio, insulation resistance, polarity, winding resistance | Adapted tests for QC only |
| Governing Standards | IEEE C57. series | UL, NEMA ST 20 Dry Type Transformer For General Applications |
| Inspection Focus | Ratio accuracy, insulation, oil tests | Voltage output under load, impedance, inrush, dielectric |