Electrical Distribution Systems
Figure 9 Single Phase Manual Controller
A large percentage of controller applications require that the controller be operated from a remote
location or operate automatically in response to control signals. As discussed, manual controllers
cannot provide this type of control; therefore, magnetic controllers are necessary.
Basic operations using a magnetic controller, such as the closing of switches or contacts, are
performed by magnetic contactors. A magnetic controller is one that will automatically perform
all operations in the proper sequence after the closure of a master switch. The master switch (for
example, float switch, pressure switch, or thermostat) is frequently operated automatically. But
in some cases, such as pushbuttons, drum switches, or knife switches, the master switch is
manually operated. Figure 10 shows a typical magnetic controller and its component parts.