Power Supply Selection Tips and Calculation
Keep the following requirements in mind when selecting your power supply:
Powersource, input voltage and frequency (AC/DC)
- Number of DC devices to be powered
- Voltage requirements of each DC device
- Wattage/Amperage requirements of each DC device
- Maximum/Peak draw of each DC device
- Physical space available and mounting requirements
- Check for applicable safety approvals for the location and application
The conversion of Volts to Watts is governed by the equation Watts = Amps x Volts.
Note: there are 1000 milliamps (mA) in 1 Amp.
While most power supplies allow operation at 100% of rated capacity, it is recommended that an extra 30% be factored in. This allows the power supply to run cooler, more efficient and extends its life.
Device #1 requires 24 VDC and draws 1 Amp [24VDC x 1A = 24 Watts]
Device #2 requires 24 VDC and draws 500mA [24VDC x (500/1000)A = 12 Watts]
Total wattage required is (24 + 12 Watts) x 1.3 = 46.8 Watts
Round up to the nearest 10 Watts; that would be 50 Watts.
Therefore, you would select a power supply rated