Power Supply issues:
There are two main types of power supplies that are used with an industrial chassis; a rear mounted case supply, or a front mounted card style power supply. The most common power supply style is the enclosed case type which is mounted in the rear of the chassis behind the backplane. Most case style power supplies will be the switching type which are smaller and lighter than linear power supplies. All power supplies in PC cases are switching power supplies. Most are shipped with Fans attached to the power supply case.
The card style power supply may be used in many types of backplanes. Most board specifications which define a card and backplane combination allow for a card slot to accept a power supply board. The cPCI board standard is one of many standards that allows front inserted power supply boards. The trade-off in using the board style power supply is the loss of one or more card slots in the chassis.
The power supply should be sized to supply the required cards and [DC] fans within the chassis. The power supply may also need to be sized to power empty slots, so cards may also occupy those slots if required. For operation above 50 degrees C the supply should be de-rated 20% for each additional 10oC above 50oC or 2.5% / oC rise.
Power Supply Specifications and Standards next page
How To Specify a Equipment Chassis index page
