In a star connection, each phase is obtained between one of the hots and neutral. In a delta connection, each phase is obtained between two of the hots. Given a star supply, you can still wire a delta load to it (just ignore the neutral wire). The phase-to-phase voltage will always be SQRT(3) times the phase-to-neutral voltage. You can see why this is if you do vector addition on the two voltage vectors. i.e.: the vector from phase A to neutral is 120 degrees away from the vector from neutral to phase B. If you look at the way the triangles work out you can see the distance from phase A to phase B is thus SQRT(3) times the distance between either of the phases and neutral. Some delta's are set up with one phase grounded. Other deltas are floating. This would normally be considered dangerous, but it can actually enhance safety where there is a chance of a phase being grounded. Large factories often operate with ungrounded deltas, if any one phase is accidentally grounded out the factory can continue operate while the electricians search for and repair the problem. Sounds scary, doesn't it! In my high school the auditorium lighting system was supplied by a floating delta with 120V between phases. A 100W light but was connected from each phase to physical ground. Under normal condition, each bulb would see 120V / SQRT(3) volts and thus burn dimly. If one phase was grounded due to a fault, then the corresponding bulb would go out, and the other two would come on full. Bob Ammerman RAm Systems ----- Original Message ----- From: "Ian McLean" To: Sent: Friday, January 02, 2004 10:15 PM Subject: Re: [EE:] Remote Engine Starting, WAS:Vehicular remote starting > Just to follow up, and for my own benefit as well, is there someone more > knowledgeable here about 3-phase power that can tell me how you split the > phases in an unbalanced 3-phase system (3 wires + earth). Is this where > star and delta connections come into play ? > > Rgs > Ian. > > > -----Original Message----- > > From: pic microcontroller discussion list > > [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Ian McLean > > Sent: Saturday, 3 January 2004 2:12 pm > > To: PICLIST@MITVMA.MIT.EDU > > Subject: Re: [EE:] Remote Engine Starting, WAS:Vehicular > > remote starting > > > > > > Yes, you are right. > > > > In 415VAC 3-phase here in Australia, the voltage between any phase and > > neutral is 240VAC. Just pick a hot and use that with the neutral. > > > > The voltage between phases is 415VAC. Whilst this can be > > hard to fathom, > > you need to delve into the theory of AC power distribution > > and generation to > > get a grips as to why this is the case. > > > > However, if there is no neutral wire (un-balanced), then I am > > not sure how > > you can get 240VAC from the 3-phases. > > > > Rgs > > Ian. > > > > > -----Original Message----- > > > From: pic microcontroller discussion list > > > [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of rad0 > > > Sent: Saturday, 3 January 2004 1:16 pm > > > To: PICLIST@MITVMA.MIT.EDU > > > Subject: Re: [EE:] Remote Engine Starting, WAS:Vehicular > > > remote starting > > > > > > > > > > Somewhere I saw a stand alone unit that ran on a pic. Try > > > googling for it. > > > > Rick > > > > > > > If you are going to use single phase from a 3 phase > > > generator, what do you > > > do? Do you just pick a wire and get your single phase, or > > is there a > > > procedure?? > > > > > > Thanks > > > > > > -- > > > http://www.piclist.com hint: PICList Posts must start with > > ONE topic: > > > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other > > [BUY]:,[AD]: ->Ads > > > > -- > > http://www.piclist.com hint: PICList Posts must start with ONE topic: > > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads