A. Polarity Polarity refers to the relative direction of voltage between the primary and secondary windings when terminals are connected and energized. It affects how voltages combine or oppose during testing and connection. + Additive Polarity • Voltages across the primary and
secondary terminals add together during testing (see Polarity Testing diagram on next page). Typically affect transformers rated below 200 kVA and with primary voltage windings under 8,660V.
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Applied to single- phase units. For a pole-mounted transformer, the X1 terminal is opposite H1 (see example in image)
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Subtractive Polarity •
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Voltages across the primary and secondary terminals subtract during testing (shown in diagram on next page) Standard for transformers rated above 200 kVA or with primary voltage windings above 8,660V. Found in larger capacity pole-mounted and pad-mounted transformers on higher-voltage distribution systems
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