The ADT Corp. (NYSE: ADT) is buying Reliance Protectron Inc. for C$555 million (U.S. $500 million) to expand in Canada.

Montreal-based Reliance Protectron provides monitored security services in Canada. The company has about 400,000 residential and commercial customers and brings in about $11 million in recurring monthly revenue. Reliance Protectron is a subsidiary of Reliance Comfort LP, which is owned by funds managed by Greenwich, Conn.-based private equity firm Alinda Capital Partners. 

The buyer provides electronic security, interactive home and business automation and monitoring services for residences and small businesses in North America.ADT expects the deal to help it provide better service in Canada, strengthening its operations in the country. The company, headquartered in Boca Raton, Fla., expects to move some administrative functions to Canada.

In another recent security deal, Tyco International Ltd. agreed in March to sell its fire and security business in South Korea to Carlyle Group LP (Nasdaq: CG) for $1.9 billion.