Selecting Power Supplies

Selecting Power Supplies

Overview This section provides guidelines for selecting power supplies.

Using Three-Phase Bridges

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 (seeModicon Momentum I/O Base, User Guide) (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.

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.