For a transformer rated at 67000-7200/12470Y, 500 Kva, how many bushings are on the low side?

The question pertains to the number of bushings on the low voltage side of a transformer, specifically one rated at 67,000 volts to 7,200 volts or 12,470 volts in a wye configuration.

For a transformer operating at low voltage, particularly with a wye configuration, the standard setup typically includes three bushings. This is because each phase of the transformer requires its own bushing to facilitate connections to the external circuit. In a three-phase transformer system, there are three phases: A, B, and C.

Since this transformer is not a single-phase transformer, but rather part of a three-phase setup, it commonly uses two bushings on the low side to connect the phases. However, because one side of the transformer may also be grounded (as indicated by the "Y" in the rating), it can create a configuration where more bushings could be present to accommodate this and provide a secure path to ground.

Therefore, while many might expect three bushings based on phase connections alone, in practical applications for safety and system integration, the number of low-side bushings could amount to a total of two in certain configurations, accommodating phase connections along with grounding configurations.

This reasoning supports the choice of two bushings