REGULATORS 199 



through the primary winding when at the neutral posi- 

 tion. In taking the curve, supply full load current 

 to the secondary, with the primary short circuited 

 through an ammeter, and take readings of watts second- 

 ary, and amperes primary at various positions of the 

 armature. At maximum boost position take an impe- 

 dance curve from 50 per cent full load to 150 per cent full 

 load. The full load point of impedance for general tests 

 should be taken at the maximum boost position, unless 

 other instructions are given. Always record the tempera- 

 ture. 

 Core Loss 



On the IRS type of regulator with the permanent 

 short circuit on the armature, the core loss must be taken 

 from the primary winding. The power-factor will be 

 low, due to the air gap, hence considerable care must 

 be taken in making the test. Take a core loss curve at 

 maximum boost from 50 to 150 per cent normal poten- 

 tial, also hold normal potential and take readings at 

 various positions of the armature, reading amperes 

 and watts primary. In taking single point core losses 

 for general tests, the armature should be in the maxi- 

 mum boost position. 

 Normal Load Heat Run 



The heat tests are usually made by pumping one 

 regulator back on another ; they may, however, be loaded 

 on water boxes or pumped back against a suitable bank 

 of transformers. The permanent short circuit on the 

 armature introduces complications in the heat run, 

 since at any position except maximum boost and maxi- 

 mum lower, the short circuited coil carries some current 

 if the impedance voltage is supplied from the secondary. 



The amount of current in the short circuited coil 

 depends upon the position of the armature; hence, in 

 taking a heat run, connect the primaries of the regulators 

 in multiple and apply frequency voltage at the proper 

 frequency. Ammeters should be placed in each primary 

 circuit and the secondaries should b'e connected in mul- 

 tiple through an ammeter. Place the armature of one 

 regulator in the maximum boost position and shift the 

 other until full load primary and secondary is obtained 



