How is 208 volts different than 230/240 volts?
HTML-код
- Опубликовано: 29 июн 2024
- In this quick video Bryan talks How is 208 volts different than 230/240 volts.
Read all the tech tips, take the quizzes
and find our handy calculators at www.hvacrschool.com/
Concise and dense with knowledge. Liked.
Well... he's not really clear. He made it sound like 3 phase power is actually just two phase power... but in fact it's all 3 connected together and continually changing in their voltage difference to one another.
The point is, you can only get the maximum 208 voltage between 2 of the 3 at a time, but which ones it will be changes continually.
@@marioluigi9599 I believe he's referring to use of single phase devices. So what you are speaking of doesn't really apply. And yes, it's possible for '2 phases' to power a single phase device, because it's really just 1 phase when there are only 2 wires.
@@spruce_goose5169 We call it "single phase" for historical reasons when we connect phase-to-phase loads to a 3-phase grid. I dislike this term, because it is easy to confuse it with single phase line-to-neutral loads, that are really the true single phase circuits. I prefer the term "open wye" to refer to two phases and the neutral drawn off the 3-phase grid.
@@carultch yeah. I think my point was just that any two lines, whether line to line or line to neutral, constitutes only one 'phase' in the strictest scientific sense. One sine wave, if you will.
But as far as how people speak and refer to various electrical systems and system components, there's certainly many ways. Some perhaps more technically accurate or common than others. What you say makes sense.
k yeah thx
I am not an HVAC tech, but do a bit of electronics. I had always been a bit confused about the 208 versus 240, but now I understand why there is difference. Thanks for the quick and clear explanation.
No one has been able to explain this to me and get it through to my simple brain the way that you just did. Thank you!!!!
First time this ever made any sense! Thank you
You explained this subject better than I was taught in 10 months of trade school. Thanks !!
Great video, I've been doing hvac for 14 years and still learning new things everyday.
208 can only be obtained from a 3-phase wye system. 240 volts can be obtained from either a 120/240 residential system or a 240 volt 3-phase delta system.
jmiller2705 Wonderful explanation.
For a 208V water heating system what would be the coil resistance in ohms?
You can get 208 from a hi leg delta system…
What about High Leg Delta?
A value of 208 volts can come from either a 3 phase wye or from the high leg of a delta system. And 120 can come from any of the 3 systems.
In a 240volt /120 volt spilt phase system the phases are absolutely not 180 degrees out of phase. The winding of that transformer is wound the same direction from L2 to the center tapped neutral and from neutral to L1 hence no change in phase relationship. If the transformer winding was wound one direction from L2 to neutral and wound the opposite direction from neutral to L1 then you would have 2 120 volt sine waves that are 180 degrees out of phase from each other but you would have no voltage available when measured from L1 to L2. You would have 120 volts from neutral to L2 and 120 volts from neutral to L1 and u could power 120 volt loads off of these but when you hook up a load across L1 and L2 you are going to find that there is not 240volts available. There is zero voltage. The reason why these sine waves appear to be 180 degrees out of phase is because the oscilloscope leads were not hooked up correctly to show the actual relationship of the signals. It is the same thing as hooking up a multimeter to a 12 volt dc car battery backwards. If you touch the black lead of the meter to negative and the red lead to the positive then the meter show a positive voltage but if you reverse the meter leads on the battery the meter displays a negative voltage. For anyone who doesn't believe and wants to be properly educated go over to Dave Gordon's youtube channel and find the video on 120/240 volt systems that describes what I am saying in great detail with a live demonstration board absolutely proving that it is not electrically possible for the phases to be out of phase and have L1 and L2 add up to 240 volts and power a load.
I have come to the conclusion that electricians should not speak of phases. They just don't know what they are talking about.
Thanks that explains it pretty well. I was in a panel or a three phase disconnect trying to figure out how to put a single phase unit and only get about 211 V off of two legs. Yours was the first video to explain what was going on.
Congratulations You have a special talent to communicate the most important factors in the HVAC industry, not all technicians are electricians and electricians are not always technicians, in this field you must have holistic qualities, that is, knowing how to do everything !!! Thanks for the incredible contributions from your school and your channel.
I'm an electrician, Thank You for this video, you cleared up some questions I didn't know I had.
i thought this video gets straight to the point and this guy did a great job. Thank you
Thank you very much! Your an expert here and I got a lot of info from you that I needed concerning wiring my air compressor. Wish I had your understanding of this voodoo we call electricity 😕 lol. Thanks again man.
Super great description and video.
Thanks Brian, great video 👍🏼
Great simplified explanations !
Thank you. helped allot. you are going to make me sound like i know what im talking about at work tomorow.
Great video lots of useful information that really helps a guy like me
Best explanation I have heard.
Great video and very clear to me
so it's actually impossible to get 240 out of a 120/208 service. great job of explaining.
Awesome learned several things as usual! Thank you
excellent and full of knowledge to learn .
Perfect explanation… thank you!
Thank for the knowledge!!
Great job and video like always
Excellent Description
I learned this lesson the hard way when I told the hvac company 230v exhaust fans were good for our welding shop . We have 120/208 coming off a 480v panel to transformer. Needles to say i ordered a few buck boost transformers.
Im a sparky jr and im getting alot out of this thank you
Super helpful. Thank you.
Really clear. Thank you.
Correction: 208 volts is NOT a 2 phase power source. 208 is in itself a single phase source. It is derived from two out of phase legs of 3 phase just as 120 is derived from one leg split. 208 is single phase.
Many apartments and townhouses will have 120/208Y 3ø. Each unit, however, will be fed the two legs out of three, and of course your neutral and ground, and will alternate between A-B, A-C, & B-C so as to balance the loads. It's more efficient than a single phase service but of course can present problems with motors as you described. The electric range and dryer will have 75% power for heating.
It's easier in the EU. You get either single phase 230V or three phase 400V. No split phases here. And by the way, if you import a device from Europe it should work perfectly fine on 208V and 240V as well, as long as it doesn't complain about the frequency. It's because the acceptable voltage range here is +/- 10%, so anything between 207 and 253V is correct. Every appliance has to start and work normally even at 207V
Thank you. I noticed this and was wondering. I have solar on my house and regularly see 250-257 when the sun is shining direct. It’s less than ideal for my CNC controls, I’ve blown a few capacitors and servo drives.
The "old" voltages are the plus or minus range on the nominal voltage. Lower stamped on load devices, higher on switches and things. Some areas only at nominal, say 120V, +/- 10% which ranges from 130-110, =/-5% from 125-115. Now North America has +/-5% and it's generally baked in on modern devices given the good control of the grid. Might also be what the meters read in the past as well.
I always suggest (to who? anyone that'll listen ;) that the term 'phases' be dropped when referring to wires. Those are phase *conductors.*
The reason is to avoid confusion that stems from people thinking two phase conductors implies 2 'phases' when in reality that is only 1 phase.
Man you are so right. Too bad most people in the trades including the learned ones don't realize this.
Great info. again Bryan. Thank you.
At 208 VAC, you ignore voltage drop issues at your peril if you're using equipment that claims to support 208-240 VAC (single phase).
For example, Friedrich makes window air conditioners that are rated for 230 VAC and support 208-240 VAC (nominal). When Con Ed (New York City's electrical utility) announces that they're going to drop their voltage by 10% (brownout) on a very hot day, such a window air conditioner will keep going if you have nominally 240 VAC service, but if you have nominally 208 VAC service, there's a very good chance that the air conditioner's motor-protection circuitry will prevent the compressor from starting, and you'll be without air conditioning on a day when you really need it.
Whether your load is HVAC equipment, cooking equipment, or laundry equipment, you may want to design in a 208-to-240 boost transformer (or an isolation transformer if you need a neutral) and use correspondingly thicker wire on the primary side. While manufacturers often sell dual-rated equipment that operates on nominally 208-240 VAC, 208 VAC is at the low end of the range, and users may be dissatisfied by the performance, even on "good" days: cooktops delivering only 75% of the heat that they would under 240 VAC; clothes taking longer to dry; ovens taking longer to heat up; car chargers taking 33% longer to deliver a given amount of energy; and so on. And when the utility drops the voltage during a heat wave, and your equipment receives voltage well below tolerance, things get really unpleasant.
Moral of story: if your equipment isn't specifically designed for 208 VAC, then operation on 208 VAC is probably an afterthought. If it's designed for the 208-240 range, consider designing in a transformer to boost the incoming voltage by 15%.
Man thanks that was super clear and informative. I was so confused about it
I’m interested in your backstage demonstration setup, looks like something that could be built to get visuals on all sorts of things and on top of that do electrical tests, is it up anywhere?
Here in canada we get 208 via 600/347 service entry.
It’s actually 600v 3 ph transform to 208 3ph.
We don’t have 208 single phase provide by the power cie.
Thanks.
Resistive loads designed for 240V will run at 75% of power on 208 volts.
Bryan, hi glad there is not much 208 single, or 3 phase , as brownouts create low voltages, & even though you ARE using the 208 tap , on control circuit too many times contractors DO NOT PULL IN , the SQUARE ( park ) in MORRISTOWN NJ IS STILL 208 a royal pain in the seat , I was so surprised that where I was in GERMANY, the homes do have 3PHASE CLOTHS DRIER, & stove Are hooked up, unlike USA, where all your load is on both sides of 230 v single ph, thereby higher amps /leg , all there is 50 HZ , also zero 125 volts , Cheers 🇩🇪🇺🇸🇺🇸
I love it when people who don't understand what a phase is try to explain power distribution.
Yes I did make some mistakes in this one and I've corrected them in future videos. Thanks for reminding me that I need to correct it.
240 volts RED (hot) to BLACK (hot) is a single phase from a delta transformer. The split is from BLACK (hot) to WHITE (neutral / grounded conductor) and WHITE (neutral / grounded conductor) to RED (hot) [notice how the order changed, because the windings are not reversed in the transformer]. The HOT's to NEUTRAL is the split phase. The amplitude is reduced by half because the transformer is center taped.
The neutral only carries the unbalanced loads. If the loads are balanced on both sides of the split there is no current carried on the neutral from the service back to the transformer. If the windings were reversed the neutral would have to be much larger, because would carry current from each side of the split and there would not be 240 volts from hot to hot.
Delta transformers can also provide 3 phase service, but there will be one stinger leg substantially higher than 120 volts to neutral or ground. This can get you if using a pigtail on commercial systems.
If a single phase relied on another, you couldn't have single phase power.
In Europe a Neutral and a hot Phase from 220 to 240V. In most cases, no rewiring is necessary.
Thanks🎉dude
My co worker change a blower motor on a package unit and its rated 230 v and he has it on 208 terminal, and the blower is working on a low speed because of that he said its not because of the voltage.you just explained it in this video thank you
That wouldn't slow a motor down. Everything is still at 60 hz.
@@Bryan-Hensley what are you talking? Of course it slows down at a lower voltage. The motor speed is nothing to do with the phases and Hz.
The 3 phases just prevent the AC power from continually switching on and off. With 3 phases there will always be a potential difference of 208V between any 2 of the 3 phases.
...Whereas with 240 single phase, it keeps going from +240 to 0V (turned off), then to -240V (turned on), then to 0 (off again) and back up to 240 (on again).
@@marioluigi9599 absolutely wrong. The hz and rotor poles is what determines the speed a motor runs. Lower voltage causes higher amperage and will burn out the windings. Sorry dude, I'm been working on ecm motors since the 1980s. In other words almost 40 years experience. You need to shut up so you can actually learn.
@@Bryan-Hensley well I think 40 years has just confused you. Maybe you should revise basic electricity. "Lower voltage causes higher amperages"? What?
I remind you that current is proportional to voltage. If you halve the volts, you also halve the amps.
Also, if the speed of motors was determined by only Hz, you'd never be able to change the speed of any electric motors, since the frequency of power never changes. It is always 60Hz in the U, 50 in Europe.
@@Bryan-Hensley I suppose your motors can only do a speed of 60rps / 3600rpm?
Or you can use a buck/boost transformer.
Watch the video "Split phase 120V/240V is not 180 degrees out of phase" from Charles Staton
I am happy to see you bring up the fact that 208 is 2 phase.
I was working on a peice of equipment that was 208 with a supervisor and I stated that it was 2 phase and he threw me under the bus in front of all my co workers saying that I was an idiot and was completely wrong for calling single phase 208 2 phase. It made me very angry because I know 208 is two full phases. And in Europe they actually call it single phase, two phase, and three phase.
Here's the problem. It all depends on how the transformers are configured. It could be single phase, It could be two phase, it could be three phase. Everyone is right here. And everyone is wrong. The answer is it simply depends.
I agree. I'm installing an evaporator that states 208-230 single phase that takes its power directly from inside the outdoor condenser which is wired as 208 3 phase... The evaporator is simply just using only 2 legs instead of all 3. It is most definitely NOT single phase and is most definitely 2 phase.
@@etherealrose2139 not how I see it . Single phase you only get a shock from 1 of the conductors.
the reason it is called 208 single phase is because that is all the LOAD sees. Visualize just the motor - nothing else. No neutral, just the two hots. When you hook up those two different legs,the potential difference between them at the motor is 208 volts. Plot it. The voltage is just a sine wave. It is just a "single phase" as far as the load is concerned, there are no other legs peaking at different offsets to that motor, they are not seen by that motor. It's tricky to comprehend but the official manufacture literature for most motors does refer to it as 208 single phase for this reason. Just learned this yesterday/today after coming across this very issue.
It's 2 phase if you also connect the neutral of the Wye configuration to a load (actually two loads) that has a neutral and two line inputs. However if you only connect two of the lines, it's a single sine wave.
240 Single phase is not out of phase. It’s in the name. How it’s measured make it look 180 out on a o scope
I took a work force based class before I went to HVAC, and my electrical instructor would say that 120v coming out of an outlet is actually 370 volts RMS. I forgot the reason or the explanation, but it was something interesting I learned.
Actually about 350Vac 'peak to peak' voltage of the sinus-soidal 60hz waveform. Volt meters only look at the POS+ wave, then display an "averaged" voltage via multiplying the "POS peak" 175v x .707 = 124 Vac meter display. (Remember, the displayed voltage is 'static'. A.C. is ever changing. The static A.C. display is actually a D.C.voltage equivalent, after the formula above is applied. Otherwise, we couldn't the read meter display. A.C. is changing way too fast.
@Eric M I see thank you
@@BYENZER thanks for the formula I couldn't remember it lol
@Eric M 120v is the effective or root mean square (RMS) value of the AC voltage. It is the voltage that if it were direct current would deliver the same amount of average power as the alternating current with the peak value of 169.7v (120 time square root of 2) over the complete AC cycle.
@@BYENZER " Volt meters only look at the POS+ wave"
If the meter is marked "true RMS", it looks at the negative peak as well and draws the square root out its squared value (which always is a positive) to get the accurate amplitude reading.
I've always heard that our devices are designed to accept 10% more or less than the rated voltage. Indeed it fluctuates. In some countries the voltage is 127. 1.73 times 127 is roughly 220. That includes Mexico and some other Latin American countries.So I guess in them places the houses are pretty much all hooked to a 3 phase system. Idk if it's just two or all 3 phases coming into the homes
In my country Suriname, you either 127 single phase, 127/220 2 phase, 127/220 3 phase. All airconditioners work without any problems on the 2 phase.
@@VinayJhinkoe thanks. I enjoy learning about electric standards in other countries and actually have quite a collection of foreign adapter plugs
Found a RTU the other day tapped at 575v it was a 460v unit. I was only getting 21v out of the secondary side of the transformer. The unit wouldn't fire up. Re tapped it correctly and had 26v and wouldn't you know it. It fired up. I understand the reasoning behind it. Still have much to learn about electrical though
Hvac know it all did a video on a carrier rtu with those voltages. Check it out.
As others have mentioned the 120/240 circuits are not 180 degrees out of phase. Below video does a good job explaining that they are in phase.
ruclips.net/video/nOSYHUxHxG8/видео.html
They are 180 degree out of phase relative to neutral, because one is negative and the other is positive. They are in phase if you measure from one line to neutral, and from neutral to the other line. It's a matter of reference / semantics. Other than that, the point of your linked video is to not have both lines positive relative to neutral at the same time, because the line to line voltage aka voltage difference between the two positive leads will be 0.
In south Africa, we have straight 230v single phase, 3 phase is 380v
Same in Europe (DK). we just use 240V (LNE) and 400V. And nothing else... maybe at powerplant levels.
That should be 220V and 380V. The ratio between the values should be sqrt(3).
Your options are:
380/220V
400/230V
415/240V
I have an air-conditioning untit that has an odd plug on it. It reads 208/230 v. I want to hook it up in my house but need to change the plug due to its horizontal pos and neg. It also has a ground. Suggestions?
What type of phase converter would be best to use on an air conditioning unit that is 208 V 3 phase but my power source is 220V Single phase?
Why would you even do that? There's VFDs that can do single phase to 3 phase but you need to get the appropriate sized one for the horsepower of motors it is expected to drive. Usually they convert ac to DC back to ac so it gives you a cleaner signal and ability to adjust motor speed... but that's added complexity. Other option is Rotary converters but those are a bit pricey and better for larger applications. Single phase with capacitor start is really ideal even if 3 phase is usually more efficient the juice may not be worth the squeeze.
Change the motor in the aircon to a single phase motor. You can't easily convert from single phase to 3 phase
If the motor is a proper 3 phase motor then it needs 3 phases to work properly, otherwise you can cause damage to it.
It’s all about the vector angles for 208😮
That's why the 120- 208 Y system is also known as the wimpy Wye.
I=V/R
This is the reason why at a constant resistance when voltage approaches infinity current follows and the same when approaching zero.
Yeah but not true for motors because there is firstly, the load impedance is not resistive, and secondly there is a back EMF produced , which doesn't occur when the motor is not rotating
raise your hand if you have have alot of experience but accidently plugged the test leads in the dc amperage port of the voltmeter and tried to test 240 whilst customers were watching you.
Question regarding this topic... seems like I find things in 3’s. Recently I have been on some commercial building working on ‘no heat’ RTU service calls.
In these 3 different instances I was getting 16-19 volts at the thermostats only to find whoever installed the units must not have done a proper start-up. I found the transformers still at factory tap of 240 when they should have been retapped to 208. So as I retap the transformer BOOM I get 26+ volts for my control voltage (good)!
Could you explain this? And how hard is a incorrectly tapped xfmr on controls and control circuits.
In my case, 2 of the calls had companies out who were continually just replacing thermostats that kept malfunctioning. Soon as I put the tap on correct voltage they have not had any issues and now we have new customers!
Thanks
Tony
Tony Frost, that job in a low voltage time, could have the contactors NOT PULL IN , seen too many units like that, installer DID NOT CHECK One of the worst has been TRANE , CHEERS 🇺🇸🇺🇸🇺🇸🇺🇸
The sound wouldn't go on so I had rely on your written statements of the talk
soooooooooooooooooooo goooooooooooooooooood.
I din it ironic tat you would have motor startup problems with three phase as it is intended just to solve that. The proper use of three phase is to have all high power loads designed for three phase.
Make a video about the 480volt step down to 240volt with a 208volt high leg transformer.. I've seen alot of maintenance guys fry equipment because they thought the B phase(high leg 208volt) was a normal 120volt circuit.. you always gotta open the panel up and make sure it isn't a 208volt high leg.. we mark the high legs with orange tape but most maintenance guys don't know what to look for..
That only happens with delta 3 phase. The high leg being on the B phase is the CURRENT regulation. There still are a lot of C phase high legs out there. ALL UTILITIES still deliver the high leg on C phase, but the load panel has to have it on B phase now unless it was installed prior to the regulation change. Be careful when doing service changes to check which was the high leg before disconnecting, 'cause if you wire a new B high leg that was perviously C high, you will fry everything on the new B since it was previously not a high leg.
@@xNYCMarcas of 1975, requires the high leg land on the B phase in a panelboard, and because high leg delta systems are usually found in really old systems and rarely installed today, you'll often run across a panel where the high leg is phase C even if the panel appears relatively new, assuming you're not rewiring the entire facility.
208 ? Yesterday was crazy because I was reading 209, 209, 209…..not 220 or 240
This would have been much better for noobs or those struggling to understand, if it was explained showing how it looks from the transformer.
agreed a visual would be nice @hvac school
👍👍
Motor torque reduces with the square of voltage, which is why relatively small voltage drops can cause motor stalling on startup, especially on hard starting loads and when voltage is low to begin with like when running 240/208 motors on 208V. 208V 3-phase sucks in general for motor loads, since they run cooler under load with the higher voltages and don't suffer from the starting issues associated with voltage drop. The only redeeming quality of 208V 3-phase is where substantial 120V single phase loads are to be served; instead of attempting to supply large 120V loads from one leg of a split phase 240/120V transformer, 208V 3-phase can be brought into the building and 120V loads shared between the 3 phases from any line to neutral.
3 phase sucks for motor loads? Rubbish.
You obviously don't know why 3 phase exists and how fundamentally important it is for motors.
@@deang5622 You didn't read my comment properly. I said 208V 3 phase. 3 phase exists in voltages other than 208V (not everywhere of course, but it still sucks).
@@Orgakoyd Yes I did read your comment properly. It was in fact you that did not read my god damn comment properly. I made a statement about 3 phase and I made no mention of the phase voltage. And the reason I did not make any mention of phase voltage is because it it is not relevant.
@@Orgakoyd What are you, an electrician?
@@deang5622 Your origiinal reply implies I said 3 phase in general is bad for motor loads. Maybe you misunderstand what I'm trying to say. I meant 208 V 3 phase isn't as good as 240V 3 phase for motor loads. I am not an electrician, just interested in things.
So a 240V is split into two 120V output? Is it 120 V in amplitude, or 120 V RMS, because the chart in 1:22 shows 170 Vp and 120 Veff. Also is this different from the 240 V and 115 V switches on a computer power supply meant to accommodate American and European voltages??
Are instruments functioning in 208 V sir
question if you can help me running a VFD with this motor I have 3hp model number EM3611T. i want to power it with a house hold 220/240 single phase power converted to 3ph 230v. the VFD from amazon i want get says it puts out 3 phase 220v not 230v?
my motor is 3hp 230/460v
Im not an electrician and a bit confused with some of this , if i have a 3 pole breaker going to 3 pole contactor/overload and i have 213volts phase to phase and 123volts on each phase to ground, what do i have what is this considered!? I’ve been calling it 208 3 phase. Im wiring up a 3phase motor and there’s only 3 power wires and 1 ground no neutral.
What voltage and/or phase comes out of a capacitor on a 120v gas furnace blower motor vs. one on a 240v fan coil blower
Never ask questions to a RUclipsr. Send them an email instead. Plus, it's inconsiderate to ask them in the comments section. YES! Inconsiderate. Why? 1st, you aren't paying them. 2nd, They don't have time for you. 3rd, if they don't answer you, people will label THEM as inconsiderate. So, better PAY a fair price, for someone to take their time to answer your questions. Stop treating youtube as CAMP GIMME GIMME. Doing so makes you look a left wing, liberal, entitled democrat parasite.
370/440 I believe
I believe the capacitor also creates a 90° phase change
The voltage on a run capacitor during the motor operation is driven by the the spinning squirrel cage's induced magnetic field inducing a current in the auxiliary winding. That is why run caps have the odd voltage ratings that don't match the supply voltages.
If you'd have 180 degrees out of phase then instead of 240V it be 0 (zero) V. Hence, the split phase systems are not out of phase.
They are out phase see why
Say Van = 1.5 and Vbn = -1.5
then Van -Vbn = 3V. Yes, you can't measure the polarity of an ac waveform with a DMM but you can do it with a DC circuit and two batteries in series. Try it out!
@@shieldcracker You are wrong 😉
It's not possible to have AC, generated by a single transformer, to be out of phase with itself. Again, it is one 240V transformer with division in the half of the winding. It creates 2x120V of the same phase.
In your analogy you have 2 sources of DC. Let's say they are 2 AA batteries of 1.5V wired in series:
-[_1.5_]+ (COM) -[_1.5_]+
so together you have 3V
If you can measure voltage by attaching a COM probe of your VOM in the middle you're going to see -1.5V and +1.5V. This wiring mimics AC at the main hose panel. In phase.
When you attach COM probe at the -(minus) of the first battery and check voltage in the middle and then on the end of the series you'll get +1.5V and +3V.
To mimic out of phase you have wire those batteries "in reverse" like there:
+[_1.5_]- (COM)-[_1.5_]+
Now your VOM with COM probe attached to the middle will show +1.5V and.... +1.5V. But if you want to measure the whole circuit you get 0V -- out of phase scenario.
You measure voltage proper way or wrong way. The house system is in phase. You just measure it wrong.
@@tjblues01 Your understanding of phasing is just the opposite of what it is! The voltages -1.5V & +1.5V are not the same thing, the negative sign indicates there is 180 phase rotation relative to the positive value or vice-versa. For both voltages to be in phase they need to have the same polarity (and frequency) at all times.
These concepts are hard to visualize so here is another way to see this. Go to your breaker box and pick two circuits (say 1 & 3) on the same leg/busbar and measure the voltage across. You get 0V, by your rationale circuits 1 & 3 would be out of phase hence the 0V. However both circuits originate in the same bus therefore must have the same phase. Now if you pick two circuits, one on each bus bar and measure the voltage across you get 240V. This is possible because the voltages are 180 degrees out of phase in respect to each other, if voltages had the same phase the result would be zero which is not the case.
@@shieldcracker I don't have time to teach you about waveforms, phases, polarity, etc.
Of course DC is not the same as AC. My example was an analogy to AC as a snapshot in certain position on a sine-form.
I don't know what's your background. But it seems that you don't know much about the topic. For me it is something what I've been dealing with for last 20 years. I'm telecommunication technician. Adding and subtracting wave forms, shifting phases, amplification, attenuation, power division... and more - that's what do for living.
Please watch this:
ruclips.net/video/uRKbX74lBgU/видео.html
cheers
@@tjblues01 I provided two practical exercise ways to drive my point, first with DC then with AC voltage. Once more consider the two breakers on the same Busbar, both have identical voltages so by definition the two voltages are in phase and when you measure the voltage between the breakers it is zero, it does not add up to 240V.
I watched the video, its not well presented and the conclusions are wrong. But don't take my word or the other guy for it, consult a text book. These concepts are hard to visualize with just simple sentences and zero math. So, untill we can have a cup of cofee, we will have to agree to disagree. Regards.
Thanks for the video...but in 2:40 you mentioned that 208 is from to phases...but the motor is actually using 3 phase??...right? ...The 208 comes from when you measure the voltage between phases...it does no mater what is the phase...
What's is a hard start kit . I recently bought a 80 gal compressor with a starter motor on it that says do not use a 208 , my power supply is a genrac 22500 with running of 15000 wats. Is this considered 208v
Who knows? Read the label but most residential generators will be wired for single phase more than likely 240v. It's not impossible to have a 3phase genset but it would be typically for business use and I don't know generacs models.
208v is derived from 3 phase so the motor on your compressor is a single phase induction motor with two windings. A start winding and a run winding. Thr capacitor creates a temporary phase shift so you have slightly more than one phase as far as the motor is concerned, allowing for a rotational angle to be applied and rotation to occur. The motor isn't wired with 3 windings for 3 phase hence the label warning.
And a soft starter is far superior to hard start capacitor in my opinion. Slowly spooling up a motor rotor versus a sudden kick means less wear and tear and also way lower locked rotor amp current.
You mentioned BTU’s will this also affect latent and sensible with run time 🤷🏼
And tell me, please, which is the best choose, when I want to get three-phase system at home ?
Thank you.
ok so 3ph 230v is the same as 3ph 220v the motor company just labeled it 230v? and i want to power it with 3ph 220v the vfd company labeled 220v 3ph ? right
208v is “weak 240v,” derived from a 208Y/120 three phase system
Good way of describing it. And it all has to do with phase angles. 208Y three phase, however is more efficient for larger motors than 240 single phase, to an extent, then you get into 480 and 600V. actually when you get motors above about 10 HP , they only come in three phase. Three phase motors are much simpler in construction, more reliable and efficient
now do one on High-leg delta 3 phase
Check out Electrician U he makes great videos and has done one on three phase. Its basically just a center tapped delta. So two of the legs will be 120v to ground and one will be 208 to ground (High leg). Between each phase it will be 240v though. Mainly found in older buildings.
I actually learned about that while I was in HVAC school. I think the instructor called it unbalanced three phase.
If a 240VAC compressor runs on 208 then the performance is lower, less work, less current. If a 208VAC compressor runs on 240VAC then will it produce more work and consume greater then rated current?
funny you mention this, we had a 5 ton bryant w/heat pump installed and kept getting a line overvoltage warning, and actually the main board in the outside unit later failed (2 months old). so the power company came out and said my outdoor unit was a 208v unit and i needed a 240v unit and left, jackasses.
In commercial buildings that have 208 volts, 3 Transformers connected outside in their aerial pairs connecting to the building. So if it 2 phase what does each transformer do?
I’ve never seen a Commercial building bring just two legs of power in. It’s usually a single phase panel or 3 phase panel. With 208v appliances you would just bring two home runs to your appliance from the panel. But if you have a three phase pan el you will most likely have three phase equipment.
As far as your transformer question it’s a step down transformer from the high voltages required to minimize voltage loss over long distances. Step up transformers usually go up to 440kv from the generation station. They are transformed back down before they enter your home.
This could explain what I am seeing going to my
customers. Transformer configurations details.
ruclips.net/video/T4168xAEPqg/видео.html From Northwest Lineman College
Aren’t there motors wound for 208V though? Do some equipment manufacturers offer motor options for voltage? Are there motors which are configurable for two voltages?
This is what I would like to know. I would imagine the sine wave has to correspond correctly to the winding of the motors to function correctly without loss of power and/or heating issues since the sine waves of 2 phase 208 and split phase 240 are actually flowing in a different pattern from eachother. One is 120 degrees apart while the other is completely inverse of itself at 180 degrees. I can't imagine only the voltages being within a certain tolerance could be the only factor to consider. You also see that RPM's on 208 motors are slower than that of 240v motors.
@@Jason-wc3fh- Unless you have a 3-phase motor, the motor just sees a single phase which is 208 or 240 V RMS. All 60 Hz sine waves look the same, except for voltage.
Your diagram shows a WYE bank which would provide 240v 3phase. 208v 3phase comes from a Delta bank with a neutral tap between phases A & C. A to Neutral = 120v C to Neutral = 120v B to Neutral = 208v. A to B = 208 A to C = 208 B to C = 208. This is commonly known as a Red Leg 208v power supply with Phase B being the Red leg. The actual wire on the line side of the disconnect should have red tape on it to signify it's 208 to Neutral.
208v wye phase to phase 3-phase is very common
You are confusing phase to ground / neutral with phase to phase.
In 208v wye you still have 120v phase to neutral but 208v phase to phase
@@HVACS You are correct although I'm not confusing anything. In my area and I happen to work for a power co., 208 Delta banks dominate unless it's a 440v supply. I teach HVAC for said power co and put more emphasis on the existence of the Red Leg systems for two reasons. 1, They're very common in our industrial parks, 2, for safety. It's better to assume you have a red leg system than a WYE system. We typically use the Delta bank due to the increased power factor.
@@RalphMercuroMusic Please explain how delta transformer increases power factor?
The way you're explaining how the 208 voltage is derived is not accurate. It has nothing to do with the phases being 120 out of phase with each other. It has to do with how the wye transformer is wound for the 208 volt secondary. 208 volt divided by the root of 3 (1.732) will give you 120 volts which is why you still get 120 line to neutral on a 208 volt 3 phase system. And lowering the voltage will give you higher amps, always. But only to an extent. You're not going to replace the 32 volt loss between 240 and 208 with amps. So in part you are correct on that. Over all very informative video and it sounds like you have a pretty good grip on the subject. Not all stationary engineers possess the answers to the why's.
Yep, 3 phase is 120* out of phase. 120 + 120 + 120 = 360* a full circle.
Thanks for the confusion. Lol
I was looking at an outlet at a restaurant that is supposed to be 120 V but it was reading 215V I open it and tested one lead to ground I was getting 215V the other lead to ground was reading 0 V, so why do I have 215V in one wire
Because someone wired in two of the three phase legs of 208 to the receptacle versus 1 leg and a neutral. Or they wired in one leg that isn't tapped to neutral so the reference is still 208v. Should be able to change that at the panel assuming they didn't pigtail it off some 3 phase connection after the panel. Then you need to find that junction and swap some wires
Phase to phase is 208v. Phase to neutral is 120v. Phase to ground on the unsplit coil is 208v, phase to ground on tapped coil should be 120v.
In most European countries, the official range for the low voltage grid is 230 V +10/-10%, which is 207-253 V. So it should be possible to run 230 V equipment on a 208 V supply, but it's very close to the limit.
Many are dual voltage for basically that reason. Might lose efficiency but adds flexibility
Actually it is 400 V which makes the phase to neutral 231 V.
You are confusing two difference things: nominal voltages and their differences and variation within a single nominal voltage. This is a very common error people make.
If there is 10 % variation then 208 V can be 187-229 V. 187 V is way below the range. You must compare nominal to nominal or a range to a range, not nominal to a range.
Now part of motors under-voltage is no really an issue. It just makes the device less efficient.
Love it. Nothing whatsoever confusing unless you’re a root vegetable 😂
Tings Fretworks, what did you call me! Lol.
@@rogerbettencourt9654 i know right? Had to check my shoes to c if roots were sprouting.
How is 3 phase 240 created then is it also a split phase and not A, B, and C phases
Eric M Delta transformer has a Neutral Tap???
@Florida Man HVACR No that is not how 3 phase is generated. It is not done in the transformer.
It is done by the generator in the power station, by having multiple coils wound in the generator that are physically arranged 120 degrees angle of separation from each other.
Look at the high voltage overhead power lines, they are in groups of three, one for each phase.
@Florida Man HVACR No it doesn't.
The distribution transformer feeding power to the homes, the secondary winding is wired in a star configuration with one end of all 3 windings is commoned together. That IS the point where the neutral line is connected. The other 3 lines coming out from the secondary side of the transformer are the phase conductors.
wait you can shift phase angle on secondary transformer wire? how
Inversion by transformer is the same as a 180 degree "shift."
Centre tapped transformer on the secondary winding.