Direct Current for Power
A Direct Current power source provides a constant voltage as opposed to Alternating Current which supplies an oscillating voltage. All types of batteries are direct current such as alkaline, lithium, lead acid and others. Other sources of direct current include electronic supplies like the 5V from a USB charger and many laptop power supplies.
Direct Current is abbreviated as "DC".
"VDC" stands for Volts DC. For example if you saw 12VDC, this would mean 12 Volts DC.
Where does Direct Current come from?
Typically Direct Current comes from a DC power supply. While AC (i.e. Alternating Current) is readily available from the AC outlets found in homes, offices and commercial/industrial buildings, DC often needs to be derived from an AC source. DC power supplies are used to convert AC to DC.
DC power supplies can range in output from the small USB supplies used to charge cell phones to industrial power supplies used to run high powered machines in the hundreds or thousands of kilowatts.
Increasingly, DC also comes from batteries. Mobile applications like electric vehicles, mobile robotics, portable devices and more are only possible because batteries are able to supply the power that they need.
AC is just not a practical option for many applications because it's very costly to lay down AC supply lines (for example trolleys and electric trains) and the range of operation is limited to where the AC infrastructure was built.
As batteries (and other portable DC supplies like supercapacitors) have become smaller and more powerful it has opened up the possibilities for new innovations in mobile technologies.
DC Power and Servo Drives
ADVANCED Motion Controls has a large selection of servo drives that operate in the low DC voltage range. Many servo drives operate from 10-55VDC, 20-80VDC, 40-190VDC which makes them perfect for battery powered mobile applications.
Higher voltage DC servo drives go up to 300, 600 and even 800VDC. For these types of applications they can be powered with batteries, but in industrial settings they are often powered on a common DC bus supply.