24 6 PHASE CHANGERS, ETC [Exr. 



capacity for the 3-phase side of each transformer when the total 

 power output, on non-inductive load, is 100 watts ; see 24, 

 Exp. 6-A. 



ii. Instructions for Special Transformers. These instructions 

 relate to two transformers, DEF and a/?y8. Each transformer has 

 two primaries, which may be connected in series or in parallel. The 

 windings are as follows: 



Primary a , no (or 165) volts. Primary D, no (or 165) volts. 

 Primary/?, no (or 165) volts. Primary E, no (or 165) volts. 

 Secondary y, 368 (or 55) volts. Secondary F, 63.5 (or 95.25) volts. 

 Secondary 8, 36 (or 55) volts. 



The first number gives normal voltage for highest efficiency at 60 

 cycles ; the number in parenthesis is 50 per cent, above normal voltage. 

 These transformers were specially made for use at either voltage. 



With D and E in parallel on one phase, and a and (3 in parallel on 

 the other phase of a 2-phase system, connect F to the middle point of 

 y and 8 connected in series, thus making a T-connection. From 

 2-phase circuits of no volts (and also 165 volts) obtain 3-phase 

 secondary voltages by computation and measurement. Make the 

 primary connections from no-volt 4-wire 2-phase system, and also 

 from no-volt 3-wire 2-phase system. 



Repeat with primaries in series instead of in parallel ; compute and 

 measure secondary 3-phase voltages. 



Perform corresponding transformation from no-volt 3-phase to 

 2-phase. What two 2-phase voltages can be thus obtained? 



12. Monocyclic Transformation. In the monocyclic system 

 (no longer being installed) a single-phase voltage is combined 

 with a quadrature voltage of one fourth its value ; thus, in Fig. 6, 

 Exp. 6-A, a monocyclic voltage is obtained from A^A 2 b z . It 

 is an unsymmetrical 2-phase system. If two I : I transformers 

 are used, the primary of one being connected to AJ) 2 , of the 

 other to A 2 b 2 , the secondaries (with two ends together for a 

 3-wire system) will give a monocyclic voltage the same as the 

 primary. This secondary voltage is an open delta with one side 

 reversed. Test this with a voltmeter and draw a diagram of 

 voltages. 



