11.4 Power Control
Electrical power for actuator operation can be controlled from low-level analog
and digital signals using electronic power devices or magnetic contactors.
Magnetic contactors have a lower ON resistance than electronic devices but
require higher drive power. Contactors provide voltage isolation between the control
signals and output power circuits, but are slow to switch, have lower current
handling capability than electronic power devices, and have a limited
switching life. In electronic devices the problem of electrical isolation between
drive circuits and output power circuits can easily be overcome with the use of
opto-isolators. Electronic power devices have excellent longevity and are very
advantageous due to their switching speeds in variable power control circuits.