146 



Electric Transformers. 



No. 50 700 



starting on half load. For regulating the voltage a combined Starting and Regulating Rheostat can be used in place 

 of the simple starter; with these the speed of the transformers can be reduced by 50% at full load of that given 

 in each case. 



The transformers require no transmission drive and are therefore as a rule supplied without belt pulley; they 

 are connected up to the direct current network in the same manner as ordinary shunt motors. These transformers 

 can be employed as Direct Current Motors; for this purpose, and when desired, they are supplied with a belt pulley 

 at the extra prices shown in the table. The outputs when used as motors are shown in the table. When constructed 

 thus with belt pulleys the transformers can also be used as direct, alternating and three phase current Dynamos. 

 If it be desired when using the transformers as dynamos to obtain the voltages given, they must be arranged 

 to work in such manner that the speed is from 20% to 25% higher than that given. Shunt Regulators are ne- 

 cessary for regulating the dynamo voltage, the prices of these regulators being quoted on application. 



The capacities given for the alternating and three phase current only hold for non-inductive load, i. e., taking 

 cos <f = 1. With inductive load the wattage decreases with increase of phase-displacement between current and 

 voltage. The periodicity of the alternating and three phase current is in the (two pole) transformers to 3000 volt- 

 amperes equal to the number of revolutions divided by 60: this value being '/3o lh of the speed in the case of 

 the larger (4-pole) machines. 



Direct-Alternating-Three Phase-Direct Current Transformers, for transforming 220 volts Direct Current 

 into (about) 150 volts Alternating, (about) 130 volts Three Phase and (about) 65 volts Direct Current. 



*) When ordering, in addition to quoting the List Number, kindly mention the letters a, b, c, etc. placed 

 in front of the price lines. 



These machines (constructed as rotary converters) combine a Direct-Direct Current Transformer with a 

 Direct-Alternating-Three Phase Transformer. The transformers have on one end of the armature a commutator 

 for leading in the network current, and 4 slip rings; the interlinked three phase current can be taken off by 

 3 slip rings and the single phase alternating current by 2 slip rings. It is also possible by using all four slip 

 rings to take off a two-phase alternating current, this being of course somewhat unsymme.trical. 



These transformers are also supplied for connection to 110, 440 or 500 volts, the prices and outputs being 

 the same. 



These machines are started as simply as an ordinary direct current motor; thus it is only necessary to 

 move the lever of the starting rheostat and the low-tension alternating, three phase or direct current is available 

 forthwith. A Starting Rheostat for starting the transformer must be ordered along with the latter. The starters 

 given in the table permit of the transformer running on half load. For regulating the voltage, instead of a simple 

 starter a combined Starting and Regulating Rheostat may be employed; with this it is possible to reduce the 

 speed at full load by about 50 % of that mentioned. 



The transformers do not require any transmission drive, and are therefore as a rule supplied without belt 

 pulley; they are connected to the network in the same manner as ordinary shunt motors. The transformers can 

 also be used as Direct Current Motors; for this purpose, and when desired, they are supplied with belt pulleys 

 at the prices given in the table. Their efficiencies as motors are stated in the table. When constructed with a 

 belt pulley the transformers may also be used as Direct-Alternating and Three Phase Dynamos. If when used 

 as dynamos it is desired to obtain the voltages given, they must be arranged to work in such manner that the 

 speed is from 20 to 25 per cent, higher than that given. For regulating the dynamo voltage special Shunt Regu- 

 lators are necessary, prices of which will be quoted on application. 



The values given for the alternating and three phase current efficiencies only hold for non-inductive load 

 - on the assumption that cos <p = 1. On inductive load the wattage decreases with increase of phase dis- 

 placement between current and voltage. The frequency of the alternating and three phase current is in the 

 cass of the (two-pole) transformers up to 3000 watts equal to the speed divided by 60, and in the case of the 

 larger (four-pole) it has the value of l M th of the speed. 



