Reversal of Direction of Rotation
The rotor can perpetually flip from the beginning winding to the adjacent run winding of similar polarity. Therefore, the connection between the beginning and run windings should be modified. to alter the connection and therefore the direction of rotation, the polarity of solely.
One of the fields should be reversed. during this manner, only 1 field polarity can modification, and therefore the rotor can still move toward the run winding of a similar polarity because the begin winding. the present coming into the run winding or the present coming into the beginning winding should be reversed, however not each. Figure 17-19 shows a schematic of the reversal of the beginning winding. If the most power
Split-Phase Motor Applications
Split-phase motors area unit typically restricted to the l/3 H.P. size. they’re straightforward to manufacture and cheap. The beginning torsion is extremely low and may be used for beginning tiny hundreds solely.
Capacitor-start motors area unit the foremost wide used single-phase motors within the marine engineering field. they’re found on tiny refrigeration units and moveable pumps. they are available during a sort of sizes up to seven.5 H.P. The characteristic hump on the motor frame homes the electrical device (Figure 17-21). The electrical device-start motor springs from the essential style of the split-phase motor. The split phase motor had a current displacement, between the beginning and run winding, of thirty degrees with wire resistance alone. to extend this angle and increase motor torsion, an electrical device are often value-added. the merchandise of capacitance are often wont to increase the present angles, or in different words, to extend the time between current arrival within the begin and current arrival within the run windings. In capacitance, currently leads the voltage.
The capacitor, in contrast to resistance, doesn’t consume power however stores it, therefore, it often comes back to the circuit. The combining of the inductive run (current lagging) winding and therefore the electrical phenomenon begins (current leading) winding would produce a bigger current displacement. this could increase the torsion.
The electrical device is placed nonparallel with the beginning winding. Figure 17-22 shows a line diagram of its position. Optimum torsion is often delivered if the present coming into the run and therefore the begin winding is displaced by ninety degrees. With this in mind, Associate in Nursing knowing an inductive run winding current will lag voltage by fifty degrees, Associate in Nursing confiscate electrical device are often elected. An electrical device which will effectively turn out a current lead of forty degrees would offer the optimum 90-degree displacement angle (Figure 17-23). Once the motor has earned seventy-five % of its rated speed, the beginning electrical device and begin winding are often eliminated by the centrifugal switch. it’s not necessary for this motor to control on each winding unceasingly.