<P> Isolation transformers block transmission of the DC component in signals from one circuit to the other , but allow AC components in signals to pass . Transformers that have a ratio of 1 to 1 between the primary and secondary windings are often used to protect secondary circuits and individuals from electrical shocks between energized conductors and earth ground . Suitably designed isolation transformers block interference caused by ground loops . Isolation transformers with electrostatic shields are used for power supplies for sensitive equipment such as computers , medical devices , or laboratory instruments . </P>
why is one to one ratio transformer used
to protect secondary circuits and individuals from electrical shocks between energized conductors and earth ground