Abstract: The present invention provides a compact transformer with a magnetic core having at least two leg members and two side members. Each leg member has two ends and a peripheral surface therebetween. Each side member has a generally planar body with at least two notches corresponding in cross-sectional shape and size to the end of each leg member. The sides of each notch surround and abut a majority of the peripheral surface near each leg member end. The leg member end is secured to each notch. A magnetically coupled primary and secondary winding is arranged around each leg member. The transformer is particularly useful in sending current signals to an electronic trip unit of a circuit interrupter.