A wye-configured secondary is often represented with a Y-shaped arrangement of the windings ( Fig. The other leads from each of the windings connect to the line conductors. Wye-connected transformers have one lead from each of three windings connected to a common point.

When working with delta transformers, don’t forget about the “high leg” (see the Sidebar at the end of this article).

For a delta/delta transformer, both the primary and secondary windings are delta connected ( Fig. This system is called a “Delta” because when it’s drawn out it looks like a triangle (the Greek symbol Delta for the letter D). The line conductors connect to each point where two windings meet. Delta and Wyeĭelta-connected transformers have three windings connected end-to-end. Transformers are rated in kilovolt-amperes (kVA), where 1kVA = 1,000 volt-amperes (VA). The voltage on the primary side is the “primary line voltage” while the voltage on the secondary side is the “secondary line voltage”. The voltage that can be induced in the secondary winding from the primary magnetic field is a function of the number of secondary conductor loops (turns) cut by the primary electromagnetic field. The transformer winding connected to the voltage source is the “primary.” The transformer winding connected to the load is the “secondary.” Most transformers raise or lower voltage, but isolation transformers don’t they simply decouple the primary winding from the secondary winding. Thus, the National Electrical Code (NEC) refers to transformers as “separately derived systems.” Note: This article is based on the 2020 NEC.Ī transformer transfers electrical energy (power) from one system to another by induction, with no physical connection between the two systems (other than grounding and bonding connections).

Transformers: Dark of the Moon instal