Stevenson J. Power system analysis

4

CHAER 11 SYMMETRICAL COMPONENTS AND SEOUENCI: NETWORKS

tive- or negative-sequence currents are concerned. Of course, this result could

have been anticipated from the usual -Y transformations of Table 1.2. The

relation Zy = Z/3 is correct when the impedances Z and Zy are both

expressed in ohms or in per unit on the same kilovo)tampere and voltage bases.

Example 11.2. Three identical Y -connected resistors form a load bank wi th a

three-phase rating of 2300 V and 500 kVA. If the load bank has applied voltages

V',cl

2760 V

'11

= 230() V

nd the line voltages and currents in per unit into the load

Assume that the

neutral of the load is not connected