Not As Much These Days |
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Although gamers may have a high-end graphics card that plugs into the computer's PCI Express bus, most peripheral control is in the chipset on the motherboard. See PC chipset. |
a low-voltage electrical device used for starting, speed regulation, reversing, and electric braking of DC and AC motors. It varies the electrical resistance in a control circuit and the connections in the power and excitation circuits of motors. Controllers are usually operated by means of a manual lever or a handwheel; servomotors are used for remote control.
Controllers are built as multistage flat, drum, or cam-operated contact switches. Flat controllers are mainly used where a large number of switching steps are required, as in the starting and regulation of electric motors up to 30–40 kilowatts (kW) in power. Drum controllers are used more often than other types for the direct control of DC motors up to 45 kW and AC motors up to 75 kW in power. As the drum is turned, segmented copper contacts touch fixed contacts, establishing different connections in the motor’s control circuits. For the control of high-powered electric motors where a large number of switching operations occur (up to 600 per hour), greater reliability is obtained with cam-operated controllers having rolling contacts, which provide greater wear resistance than sliding contacts.
V. K. IVANOV