562 



ELECTRICAL EQUIPMENT 



ever, since the energizing current of the operating mechanism may 

 be considerable, such as for motor-operated breakers or for the 



closing coil of solenoid oper- 

 ated breakers, it is not custom- 

 ary to rely on the control 

 switch for breaking this cur- 

 rent, and an intermediate con- 

 trol relay (Fig. 332) is pro- 

 vided for this purpose. The 

 operating coil of this control 

 relay is then connected across 

 the closing contacts of the 

 control switch and the relay 

 contacts in series with the 

 motor circuit or the solenoid 

 closing coil (Fig. 351). 



Contro1 switches should 

 always be designed SO that 

 all connections may be made 

 on the back of the panel, and 



so as to render it impossible to operate by accidentally leaning 

 against the switch. This is accomplished in the " pull-button " 

 type, which has the contacts on the back of the panel, with pull 



FIG. 351.-Connection for Control 

 Switch for Direct-current Solenoid- 

 control Circuits. 



FIG. 352. Pull-button Control Switch. 



rods brought through the panel to the handles on the front (Fig. 

 352). The switch returns to the open position by reason of a 



