216 



ALTERNATING CURRENTS 



However, if the teaser is designed for 86.6 per cent, voltage, it 

 operates at full capacity and the capacity of the system is then 



100 X 0.866 + 86.6 



100 -4- ftfi fi " = 0-928 of the total transformer capacity. 



If the ends b' and d' of the secondaries be connected, as shown 

 in Fig. 206 (a), a two-phase, three-wire system results. The 

 voltage Ed a is equal to only 86.6 volts, whereas the voltage Eb' c ' 

 equals 100 volts. Therefore, the resulting two-phase system 

 has unequal voltages. This may be corrected, however, if the 



;a) T- Connected Trauslormers giving < -'--pbase,3-wire system with 

 unbalanced voltages 



a 



(6) T- Connected Transformers giving 2-pbase,3-wire system with 

 balanced voltages 



FIG. 206. Scott or T-connection, 3-phase to 2-phase. 



line a be connected to point ai on the primary of the teaser trans- 

 former, the point ai being such that da^ represents 86.6 per cent, 

 of the total winding of the teaser transformer, as shown in Fig. 

 206 (6). This will increase the volts per turn in the ratio of 100 

 to 86.6 and will raise the secondary voltage a corresponding 

 amount. Therefore, a symmetrical two-phase, three-wire sys- 

 tem results. By tying the middle points of the secondaries 

 together, a symmetrical two-phase, four- or five-wire system may 

 be obtained, as shown in Fig. 207. 



In any of the foregoing connections, d is not the neutral of the 

 primary, as it is not the center of gravity of the voltages. The 



