Selecting Power Supplies
Original instructions
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This section provides guidelines for selecting power supplies.
Using Three-Phase Bridges
CAUTION
RISK OF ELECTRICAL SHOCK
Do electrically isolate the AC-to-DC converter between the input (primary) and output (secondary). Otherwise, voltage levels can be propagated to the output if the AC-to-DC converter fails.
Failure to follow these instructions can result in injury or equipment damage.
Unfiltered three-phase bridges can be used in 24 VDC power supplies for the I/O bases, the sensors, and the actuators. In view of the maximum permissible ripple of 5%, monitoring for phase failure is necessary. For single-phase rectification, the 24 VDC must be buffered to ensure conformance to the specifications in System Specifications (20...30V; max. ripple 5 %).
Provide Reserve Capacity
Startup transients, extra long cables, and low cross-sectional efficiency can lead to voltage supply breakdowns. Therefore, you should select power supplies with enough reserve capacity and select the proper cable lengths and cross sections.