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Top 5 Mistakes to Avoid When Choosing Power Supplies

August 9, 2021

The power supply may be one of the least-considered components of an electronic system. After all, how hard can it be to find the right power source for your system? You figure out how much current you need at the voltage your system will operate at, find a model that can supply that voltage and current in a catalog or on a website, then make the purchase.

asterionActually, it's not that simple. There are many other things that you need to think about choosing and using a power supply.  Here are five common mistakes that engineers make when choosing and using a power source for their projects:

1. Not buying a supply with enough output power. While you certainly don't want to buy a supply with too much excess power output, trying to save money by buying a supply with just enough power output isn't a good idea, either. Buying an undersized power supply won't save you money if you have to replace it with high power supply at some later date. To avoid this, consider future as well as current needs and buy a supply with at least 25% capacity above current needs.


2. Not buying a supply with enough output current. Even though a power source might be able to supply a certain amount of power, it's not a given that it can supply every voltage/current combination. For example, a 1,500 W DC power supply with a 400 VDC range may only be able to supply 3.75 A maximum across the entire range. AMETEK Programmable Power's Asterion AC power sources overcome this limitation by using iX2 current-doubling technology. iX2 current-doubling technology allows Asterion power sources to linearly increase the output current and maintain maximum power output as the output voltage drops from the maximum output voltage to half that value. No other power source can deliver full output power over such a wide voltage range. iX2 current-doubling technology eliminates the need to buy multiple sources or overpowered sources to run tests at low line voltages.

3. Not considering startup conditions. Many AC-powered products, such as switching power supplies and electronic lighting ballasts, draw high start-up currents to charge capacitive circuitry. Excessive inrush currents not only cause lights to flicker, but can also damage the power supply. Depending on what you're powering, the power source may have to be able to supply this amount of inrush current.

4. Not paying enough attention to wiring. Once you've selected the appropriate power supply for a system, you need to connect it to the system. If you're supplying high currents, make sure that you select power cable large enough to handle that current. Refer to the National Electrical Code for these values. One rule of thumb is to keep the leads as short as possible. This will minimize the voltage drop in the power cables. When tolerances are tight, consider using a feature called remote sensing. AMETEK power sources with this feature allow you to sense the voltage with a second set of wires at the power input to a system and regulate the output voltage based on this value.AMETEK-Asterion-AC4U (2)

5. Poorly designed rack mounting. Because many of AMETEK Programmable Power's power sources are designed to supply relatively high power, they are often mounted in a 19-in. rack. One is a lack of cooling. Always ensure that the equipment in a 19-in. rack is properly ventilated to keep operating temperatures within specification.

For more information on choosing and using AC and DC power sources, contact AMETEK Programmable Power by sending an e-mail to sales.ppd@ametek.com or phoning 800-733-5427.