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## How many secondary windings does a control transformer have?

There is really nothing special about a control transformer except that most of them are made with two primary windings and **one secondary winding**. Each primary winding is rated at 240 volts, and the secondary winding is rated at 120 volts.

## What is the difference between 2 winding and 3 winding transformer?

For the short-circuit test, the two winding is **short circuit**, and the third winding is kept open. In the third step, the second winding is opened, and the first and the third windings are short-circuited. Low voltage is applied to the third coil and full load current flows through the first windings.

## What should be the number of turns in the secondary winding?

If the secondary output voltage is to be the same value as the input voltage on the primary winding, then the same number of coil turns must be wound onto the secondary core as there are on the primary core giving an even turns ratio of **1:1 (1-to-1)**.

## How do you know how many turns a coil has?

For a given coil area (length * layer thickness) I get around **75% of the turns** I calculate by dividing that area by the wire cross-sectional area. So for 10sqmm and 0.00501sqmm wire cross-sectional area that’s about 1500 turns that would fit in there.