VisionXP Low voltage dc power connectors pin, often referred to as barrel connectors, have both current and voltage ratings specified by the manufacturer. These ratings ensure reliability when using these connectors in power delivery applications. Both the jack and the plug of barrel connectors feature one exposed conductor and a second recessed conductor. A benefit of the recessed second conductor is that it is difficult to accidentally create a short between the two conductors. Additionally, there should be little concern that sensitive components will be damaged by plugging a power connector into an incorrect receptacle since barrel connectors are almost exclusively used to supply power to electronic devices.
The standard dc barrel plug or jack has two conductors, one each for power and ground. Convention is for the center pin to be power and the outer sleeve to be ground, but reversing the connections is acceptable. Some power jack models include a third conductor which forms a switch with the outer sleeve conductor. One use of the switch function is to detect or indicate the insertion of a plug. Another use of the switch function is to select between power sources dependent upon whether a plug is or is not inserted into the jack.