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.
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.
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.
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.
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
@@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.
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.
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.
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.
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.
As a European I must say, North American 120/208 V and 120/240 V system is a joke. Lower voltage, higher losses in the wires compared to our 3 phase 230/400 V system.
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. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-T4168xAEPqg.html From Northwest Lineman College
so as an architect studying for my exams, it asks me when we would use three phase 120/208 power. the book is known for asking outdated questions. What I am taking away from this is that 208 is when you are only using 2 of the 3 phases? sorry. I've watched this twice now and it's not clicking
He words it wrongly. You're using all three phases. But from phase to phase you'll have the potential difference of 208v. The 120 is each of the phases tapped to neutral.
It is generally light-commercial or multi-dwelling residential, where you would use 120/208V three phase. In a light commercial application, you would use 120/208V, and you'd have a mix of 120V single phase loads like lighting and receptacles, and motor loads and other high power loads that use either 208V phase-to-phase, or that use the full 3-phase 208V circuits. In a residential application, like a multi-dwelling apartment building, each dwelling unit gets two phases and a neutral from the 120/208V 3-phase service to the full property. The choice of which 2-phases is staggered from dwelling unit to dwelling unit, in order to balance the load as much as possible. Most residential loads run off 120V line to neutral, except for loads that use heating elements like dryers and ovens. Heating elements are a lot less voltage sensitive and the same unit can run off both 240V in a single family or duplex home, or off 208V, with the essential difference being that it only has 75% the heating power at 208V. The common loads panel is usually the full 3-phase, powering loads like common area HVAC and general lighting. In a heavy commercial or industrial application, 277/480V is the most common service you get, although there do exist applications with 347/600V instead (common in Canada). You usually use a customer-owned step-down transformer to feed the minority of loads that require 120V or 208V, like your receptacles. There are some scales where utilities only give a 277/480V service, and the onus is on you to step it down where you see fit. You almost always will have 120V somewhere in the premises wiring to feed your receptacle loads, at least in the USA. This is usually a minority of the loads on larger scale services that use the voltages over 250V to ground.
@@etherealrose2139 Not necessarily true. You can use two phases, 120 degree phase shifted to provide the power. You don't have to use all 3 phases but it is better if you can.
Explanation is incorrect and dangerous, what does a AC tech need to know. 208 is used to run office 120 outlets and if used for 3 phase AC has to have equipment rated for 230/208 as to 240. Math for 208 is 208-120=88 volts 208v is not in perfect phase.
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.
Sure about that? Lest look at a 3 phase star system. You may draw a phasor diagram showing the vectors 120 degrees apart. If you measure the length of the phasor it is 230Vrms (European 230/400V TN network). If you measure the distance from arrowhead to arrowhead you get 400Vrms. Now take the strange US split phase. If the two phasors are in phase, they coin-side. What is the distance from arrowhead to arrowhead? Zero, zero at any point in time. There is no phase angle difference between the two. Or? If you draw to phasors, one pointing up, the other down. NOW you get 240V between red and black wire. What is the phase angle between the phasors? Happens to be pi radians or 180 degrees. “Phase” in electric vocabulary is a tricky word. May mean a voltage, a conductor or a phase angle. People mixes up and get confused.
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.
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. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nOSYHUxHxG8.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.
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.
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.
It is NOT 2 phase power. If you take any 2 legs of a 3 phase system, you have single phase. A phase is any 2 or the 3 legs. So AB, BC and AC are the 3 phases. Any of those 3 would be single phase power. Two phase power is an old obsolete power system.
This is difficult to explain without an illustration. Please draw the electrical symbol of a secondary of a transformer with a center tap. Next, obtain a two channel floating ground oscilloscope (a floating ground oscilloscope is essential for this step and the reasons why will be discussed later). Attach the black lead from channel one of this oscilloscope to the bottom of the transformer and the red lead to the center tap of the transformer. Then attach the black lead from channel two of the oscilloscope to the center tap and the red lead to the top of the transformer. You will notice that the oscilloscope output shows two 120 volt RMS sine waves at 60 Hz. You will also notice that the sine wave output from channel one and channel two hit the peak at the same time and hit the valley at the same time. The author of this video, most likely not having a floating ground oscilloscope, hooked up channel one such that the red lead was attached to the BOTTOM of the secondary of the transformer and the black lead (grounded lead) was attached to the CENTER TAP whiich is opposite of the previous scenario. Channel two of the transformer was hooked up to the transformer with the black lead attached to the center tap and the red lead attached to the top of the transformer (the same way as the previous scenario). This causes the 120 volt RMS signals to appear out of phase as shown in this video which is incorrect and is the source of confusion shown in a great many videos in this topic on RU-vid. If you connect the non floating ground oscilloscope in the way described in the first scenario, the channel one black lead will be at 120 volts RMS while channel two's black lead will be at 0 volts. Since the black grounded leads in the non floating ground oscilloscope are tied together inside the oscilloscope, there wii be infinite current through the black leads and through this type of oscilloscope which lets the smoke out immediately! This is because Irms = Vrms/R and if the black leads are tied together, R becomes zero causing I to be infinite. The key here is to hook up the leads on the proper type of oscilloscope to the secondary of the transformer in a way that follows polarity correctly. If it is done incorrectly, data is reported incorrectly. Hope this helps.
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
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: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-uRKbX74lBgU.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.
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
That was incredibly helpful. I've had about a hundred conversations about single v. three phase, 208 v. 240, etc., and it was never clear till I watched this video. Thanks man!
Hello there. I know when you have a 208 convection oven you have to boost the start up or that oven will be over worked and burn out easy. so yes 208 is way different from 215 and up. However many 208 systems are single phase. Units being 208~240 Volts are very good. They manage v spikes and voltage drops better.
Good explanation but I would specify a 3-phase condensing unit for use on 3-phase. One of the advantages of a 3-phase motor is power delivery. As your diagram illustrated your power is never at zero like with single phase.
But exactly why in America/Canada there are how much different tipe of voltage setup?!?!? Aren't most simplest have the same configuration to all oder world?!? For example, here in Italy I have a 230v single fase (Fase-Neutral) in my house and in facilities there are 3 phase 400v (F-F) and 230v (F-N) and Stop! There aren't oder configuration!!! Aren't most simple???
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
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.
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.
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?
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
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.
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 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.
Split-phase is NOT two separate, discrete phases. You can't get multiple phases out of single phase service without a phase-converter. Split-phase is simply two HALVES of the same phase. You can use the halves by connecting to one leg and neutral. You can use the ENTIRE phase by connecting to both legs without the neutral. They aren't separate phases. They are NOT 180 degrees out of phase either.
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
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.
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 🇺🇸🇺🇸🇺🇸🇺🇸
Good video - but you are interchanging the word “phase” and “pole”. The power coming to your home in the USA is all single phase. To get 240v you are using 2 poles 180 degrees out of phase. Those two phases being opposite sin wave add to 240. Of you tried to get 240v from two brackets on same pole, they would cancel and you would get 0V
and you just interchanged the word "phases" with sine waves when speaking about 240 when there is only ONE phase with 240 with two opposing sine waves from a split transformer.
@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.
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??
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%.
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?
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 🇩🇪🇺🇸🇺🇸
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...
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.
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.
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.
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.
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
Never ask questions to a RU-vidr. 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.
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.
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.
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.
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
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.
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.
