I look forward to watching your 3phase video. I was curious about why someone may want to use 2phase when we have 3phase system until you said that it is an obsolete system. Anyway, it was a nice video 👏
I heard that Pennsylvani and Philadelphia still has lots of 2 phase equipment and some also exist in new york.Some industries can also have old 25 and 40 Hz equipment.
OK, so I ran across a really old 2-phase motor and was working on a replacement. I put an amp meter on the 2 phases I found at the disconnect and took a voltage reading too. I wanted to calculate total motor power to see if the current motor is sized correctly for the load. I put them into a spreadsheet to calc power. However, that spreadsheet used P = V * I * sqft(3). I think that for a 2-phase system that was wrong. Would I actually just add the amps from the 2 wires together to get the power? As is P = V * (Amps1 + Amps2)
2 phase power is still used in Philadelphia PA and Hartford CT USA. The provider supplies 3 phase but uses a Scott transformer at old buildings that are wired for 2 phase. It was my understanding that the primary advantage of 2 phase was that it could be used to start motors with no additional starting mechanisms. Also the case for 3 phase.
Kind off ... but the 2 phases that you get still aren't used as 2 phases but single phase with 2 voltages. Double the voltage, double the power on same cross sectional area.
If a consumer is supplied with two phases of 230VAC using 2 cables from a 3-phase 400VAC system with 3 cables, the current calculation for the two phases must account for the factor of √3.
In the system you're describing (single phase two legs) you have 180 degrees between the two phases, so the two in series give you twice the voltage). In the two-phase Philadelphia system, there is 90 degrees between the two phases.... so if you put the two phases the crest of one is at the trough of the other and the sum is zero volts.
I heard of two phase in the 1890s and early 1900s, but never understood the purpose until I really got into electronics, then it began to make sense because a capacitor tends to shift the current phase by 90° and causing a moving magnetic field to get a motor turning.
Capacitors only came later, pole shading was the first method, still used today in low power applications since it's such simple and reliable construction.
@@Sparky-ww5re In most modern split-phase motors the capacitors generally shift it around 15 degrees. A "run" capacitor in placed in the "start" winding. I'm not and electrical engineer but it has something to do with back EMF on the second (start) winding and motor efficiency.
@@nunya___ oh thx. Interesting. Wasn't sure exactly how many degrees the capacitor shifts the phase, but since capacitors are used in modern high power factor magnetic HID ballasts for example, to combat the inductive nature of these fixtures and bring the power factor closer to 1.00, most are 0.9 or a little better.
Great content, almost no one talks about two-phase 90° electrical systems. Very helpfull for me.
I look forward to watching your 3phase video. I was curious about why someone may want to use 2phase when we have 3phase system until you said that it is an obsolete system. Anyway, it was a nice video 👏
I heard that Pennsylvani and Philadelphia still has lots of 2 phase equipment and some also exist in new york.Some industries can also have old 25 and 40 Hz equipment.
houses in north america use a single split phase system to provide 2 hot legs and a center tapped neutral.
He explained that this is different from split phase.
OK, so I ran across a really old 2-phase motor and was working on a replacement. I put an amp meter on the 2 phases I found at the disconnect and took a voltage reading too. I wanted to calculate total motor power to see if the current motor is sized correctly for the load. I put them into a spreadsheet to calc power. However, that spreadsheet used P = V * I * sqft(3). I think that for a 2-phase system that was wrong. Would I actually just add the amps from the 2 wires together to get the power? As is P = V * (Amps1 + Amps2)
2 phase power is still used in Philadelphia PA and Hartford CT USA. The provider supplies 3 phase but uses a Scott transformer at old buildings that are wired for 2 phase. It was my understanding that the primary advantage of 2 phase was that it could be used to start motors with no additional starting mechanisms. Also the case for 3 phase.
Kind off ... but the 2 phases that you get still aren't used as 2 phases but single phase with 2 voltages. Double the voltage, double the power on same cross sectional area.
Hot doesnt carry current from the load and neutral doesnt return it.There is no direction in AC as polarity swaps at 50 or 60 Hz.
If a consumer is supplied with two phases of 230VAC using 2 cables from a 3-phase 400VAC system with 3 cables, the current calculation for the two phases must account for the factor of √3.
What's the difference between 2-phase power, and basically using 2 hots and a neutral to power a dryer or air conditioner in a normal home?
In the system you're describing (single phase two legs) you have 180 degrees between the two phases, so the two in series give you twice the voltage). In the two-phase Philadelphia system, there is 90 degrees between the two phases.... so if you put the two phases the crest of one is at the trough of the other and the sum is zero volts.
Philly electrical work ole son! 2 phase was to get motors turning in 19dickity2 before starting capacitors came around.
I heard of two phase in the 1890s and early 1900s, but never understood the purpose until I really got into electronics, then it began to make sense because a capacitor tends to shift the current phase by 90° and causing a moving magnetic field to get a motor turning.
Capacitors only came later, pole shading was the first method, still used today in low power applications since it's such simple and reliable construction.
@@Sparky-ww5re In most modern split-phase motors the capacitors generally shift it around 15 degrees. A "run" capacitor in placed in the "start" winding. I'm not and electrical engineer but it has something to do with back EMF on the second (start) winding and motor efficiency.
@@nunya___ oh thx. Interesting. Wasn't sure exactly how many degrees the capacitor shifts the phase, but since capacitors are used in modern high power factor magnetic HID ballasts for example, to combat the inductive nature of these fixtures and bring the power factor closer to 1.00, most are 0.9 or a little better.
Please correct figure at time 4:20. You have short circuited one of the single phase sources!
It's a crossing of wires there, not a junction.
@@adanner OK. Got it