APS experts led the design and implementation of the Refrigerated Trailer Inventory System. This system was implemented to track refrigerated trailers which connect to outlets that supply electricity to the trailer refrigeration unit. Inventory of trailers connected to outlets are taken several times a day and entered into the system for billing purposes. All duplicate readings are reported and kept as proof of usage, but companies are charged based on a per-diem rate. Pre-invoices are generated weekly, bi-weekly, or monthly depending on the billing cycle established for the company. This system is linked to the accounting system where tariffs, discounts and penalties are controlled.