Monday evening’s Institute of Musical Traditions concert featured the Scottish folk music institution Battlefield Band playing to an enthusiastic full house.  From the first notes from Mike Katz’s Highland pipes to the last notes of the encore, this thoroughly entertaining and professional group took the crowd on a delightful tour of traditional and contemporary Scottish folk music. Battlefield Band has gone through a variety of personnel changes over the 40 years since the group was formed. Besides the bearded multi-instrumentalist Katz, the core of the current band features fiddler Alasdair White (who has been with the band since 2001, when he was 18 years old), and vocalist/guitarist Sean O’Donnell. The band ripped through a strong first half which concluded with a “big set” of tunes featuring the pipes and twin fiddles. Then Katz came out solo to begin the second half, mesmerizing the crowd with the haunting sound of the pipes before being joined by his band mates. Then, as O’Donnell began singing a song about bagpipes, everything went dark. As in, the power went …