588 



ELECTRICAL EQUIPMENT 



FIG. 379. Diagram of Connections of 

 Position Indicator. 



gized from a 25-cycle, 125 volt, single-phase source; the stator 

 being energized by inductions from the rotors. 



The movement of the transmitter rotor, which is mechanically 

 operated by a handle, induces voltage in the stator winding. 

 This voltage is transmitted by the three-phase tie to the stator 



of the receiver and dupli- 

 125Volt8 - 25C?cleSupply cates in it the same polar- 



ity and voltage conditions 

 developed in the transmit- 

 ter stator, but in the reverse 

 direction. The rotor of the 

 receiver is energized in the 

 same direction as that of 

 the transmitter, and conse- 

 quently reacted upon by 

 the polarized stator until 

 their magnetic axes coincide 



and the rotors of the transmitter and receiver are in the same 

 relative position. With the rotors thus, no current flows between 

 the stators. Any difference in the position of the transmitter 

 and receiver rotors causes a flow of current and resultant torque 

 which moves the receiver rotor and dial pointer to the same rela- 

 tive position as that of the transmitter. On both the pedestals 

 and benchboard, at each side of the transmitter handle, are located 

 double push-button switches which are employed for operating 

 signal lamps, whistles and bells. 



The method of signaling is as follows: When the switchboard 

 operator desires to send a signal he turns the handle of the trans- 

 mitter until its dial indicates the signal he wishes to send. This 

 signal will be indicated on the dial of the receiver in the generator 

 room. He then pushes the button on the right of the handle. 

 This lights a lamp on the generator (Fig. 3) and blov/s a whistle 

 in the generator room to attract the attention of the man in charge 

 of the particular machine. As soon as the attendant has read 

 the signal on his receiver, he will turn the handle of the transmitter 

 on the pedestal to the same signal. He will then push the button 

 at the right of the handle, which will extinguish the lamp and 

 cut out the whistle. Next he will push the button at the left of 

 the handle, which operation will light a lamp in the switchboard 

 room and also ring a signal bell indicating to the switchboard 



