johnweaver
Member
The main service is 480/277 volt three phase panel, with a 240/120 volt step down transformer from the main service.
What is the va load on the service conductors with the following 6 motors?
115 volt 1 phase 5 hp cont duty with a name plate of 46.82 amps
230 volt 1 phase 7 1/2 hp 5 minute intermittent duty with a name plate of 33.2 amps
230 volt 1 phase 10 hp cont duty with a name plate of 41.5 amps
460 volt 3 phase 7 1/2 hp cont duty with a name plate of 9.13 amps
460 volt 3 phase 20 hp 5 minuite intermittent duty with a name plate of 22.41 amps
460 volt 3 phase 40 hp cont duty with a name plate of43.16 amps
Notice the question stated 480/277 volt main with a step down transformer of 240/120 volts.
The motor voltages are 230/115 volt and 460 volt. Is that part of the trick?
Also - Do I use the name plate amps or go to the tables in the code book?
Does intermittent duty cycles of the motors have to be taken into consideration?
Has anyone had this question and if so how did they work it?
Thanks John
What is the va load on the service conductors with the following 6 motors?
115 volt 1 phase 5 hp cont duty with a name plate of 46.82 amps
230 volt 1 phase 7 1/2 hp 5 minute intermittent duty with a name plate of 33.2 amps
230 volt 1 phase 10 hp cont duty with a name plate of 41.5 amps
460 volt 3 phase 7 1/2 hp cont duty with a name plate of 9.13 amps
460 volt 3 phase 20 hp 5 minuite intermittent duty with a name plate of 22.41 amps
460 volt 3 phase 40 hp cont duty with a name plate of43.16 amps
Notice the question stated 480/277 volt main with a step down transformer of 240/120 volts.
The motor voltages are 230/115 volt and 460 volt. Is that part of the trick?
Also - Do I use the name plate amps or go to the tables in the code book?
Does intermittent duty cycles of the motors have to be taken into consideration?
Has anyone had this question and if so how did they work it?
Thanks John