Panel redesign: Switching from ac to dc controls
-- Control Engineering, 7/3/2008
St. Charles, IL – Those involved in control systems design may remember when dc power was no where to be found in a control panel; most ac controls operated on 120 V ac, which was provided by a control power transformer (CPT) converting primarily 480 V ac to 120 V ac, according Puls Power Supplies in newsletter available on its site. If you're considering a switch from ac to dc, here are some considerations. |
| Puls ML100.200 converts ac voltage of a typical 3-phase system into regulated dc voltage. |
-As power demands have increased throughout the world, certain problems have been encountered in the control panel due to ac power surges and brown outs. Fluctuations on the extreme high or low side can cause a control power transformer to produce unwanted voltages on the secondary side, affecting the operation of the applications.
-Safety measures have also been increased by many agencies for the protection of personnel and equipment. These changes make ac controls not as straight forward to install as in years past because of the need of additional protective devices.
-Because of these ac power and safety issues, many design engineers are switching to dc components in the control panel; dc power supplies can offer better output regulation over a wider ac input range than a transformer can.
Puls explains what questions to explore when contemplating the change from ac to dc controls. Read more in “The PULS Advantage, Issue 6: ML100.200 - The Perfect Solution when Changing from AC to DC Control (PDF 524 kB).”
Converting? Puls ML100.200 converts the ac voltage of a typical 3-phase system into a regulated dc voltage, requiring two legs of the three-wire system. According to the company, this makes it ideal for when a control power transformer is changed out for a power supply. The ML100.200 is rated for 4.2A at 24 V dc (100 W), and has robust overload capabilities.
For more help in this area, read the June Control Engineering cover story: Electrical Design Software.
– Edited by Mark T. Hoske, editor in chief
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