06/24/05 ABB ACH550 Variable Frequency Drive Product Bulletin [download] (pdf, 2.08 mb) 08/26/04 ABB ACH550 Specification [download] (doc, 75 kb) 08/26/04 ABB ACH550 Unique Features [download] (doc, 42 kb) 08/26/04 ABB ACH550 Communication Strategy [download] (doc, 29 kb) 06/10/04 Efficiency of AC Drive Systems [download] (doc, 56 kb) 12/04/02 Petra Package Unit Replacement Photographs taken of a package unit replacement project at an office building in Foster City. Petra built a direct replacement for an old 40-ton Carrier package unit. The new unit dimensions matched the existing roof curb and duct openings exactly. Old Unit 1 (jpg, 982 kb) Old Unit 2 (jpg, 944 kb) Crane Lift 1 (jpg, 834 kb) Crane Lift 2 (jpg, 615 kb) Unit Placement (jpg, 982 kb) New Unit Installed (jpg, 371 kb)

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