A Scottish concern agreed to buy Powertec.

The acquisition agreement calls for Low & Bonar, a large packaging and plastics firm, to buy Chatsworth-based Powertec for $43 million. Powertec, a maker of power supplies used mainly in minicomputers and telecommunications equipment, employs about 400 nationwide and expects sales of $26 million in the fiscal year ending Oct. 31. The company will operate as a wholly owned subsidiary of Low & Bonar and will continue to have its headquarters in Chatsworth.