Read our affiliate link policy. The server's "A" and "B" power supplies should be fed separately from the "A" and "B" PDUs.Also, each server's power supplies should be plugged into the same phases.So for one server, you'd have the "A" power supply plugged into PDU "A" phases A-B, and the "B" power supply plugged into PDU "B", phases A-B.The next server would be plugged into PDU "A" phases B-C, and PDU "B" phases B-C, and so on. Cottonwood Roadster#433, Model S#S37 It seems simpler to have three evenly powered phases any of which can be paired with any other resulting in 240V power. As I've posted about before I have three phase 208v power in my shop. How do you know which type of service you have in your home? They make different models that are higher powered and can get to cone 10 at 208V 1P. Hi Kammy, First, let's get a minor detail clarified. On the little LCD screen on the PDU it'll cycle through the Phases and show you the amp draw on each. Not a rack!) So we have our power contractors here doing some rewiring and I have been tasked to see what we should do for our future server room implementation.We are going to be running far more denser server racks than we did in the past. You'll need to look at what your UPS is putting out to be sure, we have one that puts out single phase power and another that does three phase. If you were to really look on the dryers elements and motor you'll probably find that it states the voltage as 230 or 115 for the motor. So the questions I have are:Can 208V work in a 240V outlet? So far, everything's been 120/240V. And you can only use half of that. 5-20 is same, but the hot blade has a "T" on it and it's 20a. L6-30 is *not* 3-phase and should never be wired as such. In NA, the terms 220V, 230V, and 240V all refer to the same system voltage level. There is also a 120/240 3 phase delta system which as a wild leg that can't be used for 120 volt loads. Ad Choices. Everything is 120V from the servers to the outlets. When a motor is rated at 208/230 volts this means the motor will operate at the 208 volt rating, not 10% under the 208 volt rating. (Also PS efficiency is theoretically higher at higher input voltages, so less waste heat...)Anyway, my $0.02... Just to be sure.. you have considered the cooling implications of going to much denser racks, right? Our UPS main is 42 breakers so we've got 14 feeds. If you actually need to get a true 240V from a 208V supply, you can use a step-up transformer, but most likely you'll have no need to. Do you still have some lower-demand machines on 120V? Unfortunately, motors designed for use in other parts of the world are generally NOT inclusive of 208V 3 phase, because that exists nowhere but here in North America. They are not exactly the same.In the US, the term 220V and 240V are often used inter changeably. Joined Mar 8, 2011 13. A service drop rated 3-phase, 120/208V is used in small commercial applications where the main voltage in use is either 120V single phase, or 120/208V Network. Your California Privacy Rights | Do Not Sell My Personal Information Generally, any "5" series plug is 100-120v (single phase or phase-to-neutral), and any "6" series plug is 200-240v (sometimes called "single-phase 208" but that's technically incorrect as it's really a two-phase or phase-to-phase). Ah makes sense. Most computer power supplies that can accept either 120V or 208/240V are more efficient when being fed by the higher voltage. Tribus: Between the IT desk and the DJ decks. Yes we have an overabundance of cooling. With a 1:1 winding ratio, the leg-to-leg output voltage (secondary) would be 208V instead of 240V, and the leg-to-neutral voltage would be only 104V, instead of 120V. Can the motor be rewound so it will run on 240 volts? Higher density is going to mean a need for more cooling and more power for that cooling - most importantly more genset capacity so you can keep that cooling alive when the power goes out. We run most things on 120V from PDU's that are stepping down the 240V feeds from the UPS's, only quad CPU, blade centers and the core router are run on 240V due to excessive amperage draw for 120V. We needed more then that when we added the second UPS so that PDU as a subfeed going over to another rack that has 84 breakers. -- View image here: http://episteme.arstechnica.com/groupee_common/emoticons/icon_smile.gif --, © 2020 Condé Nast. Max. These are, again, assumed generalities and there are always exceptions. Likewise, can I use 208v instead of 240v? 208V is the voltage between the phases of a three-phase Y circuit which is 120V of hot neutral. For a better experience, please enable JavaScript in your browser before proceeding. Joined: Aug 24, 2013 Messages: 1,250 Location: Houston #1 Electricfan, Feb 3, 2016. Damn things will *not* die and the customer wants to run them until they drop. 208 can only be obtained from a 3-phase wye system. Thank you, drtom4444 Posts: 3,282, Reputation: 145. Ultra Member : Oct 4, 2012, 06:49 AM I would not recommend doing this, but it probably would not hurt it. That lets you get 120V between any phase leg and neutral and 208V between any two phase legs. Ideally, they'd come from separate UPSes. With your PDU, that's 8a on each of A-B, B-C, and C-A. L21-20 connectors and 5 wires for the runs. In Canada all 4 wire Delta systems have to use a panel that doesn't allow the neutral and the B phase to be connected to a single pole breaker and have to be marked as having a high leg. This can be used as you say to generate 208V between any two phases in the so-called delta wiring and 120V between phase and neutral with Wye-wiring. 2. Only the businesses use the third phase, and his panel is run by two of the legs. Regarding the use of 208V (or 240V) in a 120V country like the US, one possible concern is the use of power distribution devices like the APC unit shown in the picture. Then, the wye voltage is 120, so the delta voltage will be √3 x 120 = 208 V. This is the three-phase line voltage necessary in this case. The difference is usually 2-4% overall (80% at 120V -> 82-84% at 208/240V). Some apartment buildings are fed by a 120/208 system and each unit may have a single phase panel but it will be 208 instead of 240 because it was derived from a 120/208 3 phase system. Would a shared neutral cause problems (ie, addition of outgoing current) in the neutral wire? Click to see full answer Just so, can I use 208v instead of 240v? If you use 120v and 10A, you are drawing 10A from one leg. )Reason for 40% is that you must consider fault tolerance - what happens if one PDU feed drops? Something else? running 1 208v or 240v circuit to your rack gives you 2 120v circuits. I ask this question more out of curiosity than a need to use it. You mention US 208v so you must be deriving your supply from a 208 3ph transformer instead of the residential 240. Can a 208V motor run off 220V? That lets you get 120V between any phase leg and neutral and 208V between any two phase legs. You can generally apply +- 10% of this value to the equipment and still achieve normal operation. with. It looks like it is necessary to break this equipment into a 240V type and a 208V type, is that true? Theoretically. You should be able to change the voltage on the motor to 240 volts. The motor nameplate voltage would be shown as the "utilization voltage" and will say 230V, or better yet, "208-230V". GENERALLY, responsible motor manufactures do not list the motor voltage as "240V", that is what is referred to as the "distribution voltage". Also to make sure I am not misunderstanding since this is three phase each outlet on the PDU get's it's own phase, giving 20A per phase? What is the difference?Is it worth going with 208V/240V to get more density? Yffudcm. If cost effective, rewind the motor for 208V. Just get the electrician to install the appropriate three-phase outlet to plug them into. This is a NEMA requirement. There is one other thing that I haven't seen mentioned (I could have missed it). You should balance your loads across all of the circuits as equally as possible.Edit: There are also L14-20 and L14-30 three phase receps, but these are (at least in my experience) less common. I'm just not sure how the ATS will react to only having 208V instead of the expected 240V. Can you use 240v on 208v motor? With three typical single phase ones with 120V and 240V windings, I get 208V and 480V from my 240V … They pull the same 48 amps as the 240 volt models so they can remain a plug-and-play kiln with the same electrical hookup specs. Do certain applications require 208V? Some apartment buildings are fed by a 120/208 system and each unit may have a single phase panel but it will be 208 instead of 240 because it was derived from a 120/208 3 phase system. JavaScript is disabled. Now our HP servers don't even ship with a regular 120 straight blade power cable, it's all hooded cables that are designed for the 208v PDUs.Found during our UPS transistion that just about everything will accept 100-240v power and autosense it as well, no dip switch. In that case, servers still draw same power, but now from only the single remaining PDU. Try to keep them fairly balanced. However, 208V refers to a different system voltage level. Are there two feeds and seperate phases for this particular PDU? Anyone see anything wrong with a buck boost for this or am I giving the correct statement? 208V is *not* the same as 240V.208V is the voltage between phases of a 3-phase “Y” circuit that is 120V from neutral to any hot.. Is the amperage broken down into phases on the PDU? They're still rated to cone 10. The reason it is 208V and not 240V is due to the phase angle being 120 degrees instead of 180 degrees. End goal is to get more amperage to the racks.So I am not power savvy here when it comes to 240V/208V/120V. – Nate S. Jul 14 at 16:06. I agree, but what we see over here from IEC motor mfrs is often a version that gets a different nameplate (maybe an export version?) Actual power company voltage varies (220v / 230v / 240v) by region, but to simplify we’re going to focus on 240V. Building supplies 208V but equipment is designed to run on Power Supply of, It will probably work but it is not the most efficient way to go and it will probably affect the motors life. Frequent transfers due to what is actually a small voltage dip? I understand more or less HOW it is made (i.e. 14-50 outlet - will it work if the voltage is 208V instead of 240V? I have a 14-50 outlet at home I use for my car. Yes. In this case the motor is overvoltaged by ~ +4% and that's fine. Like Reply. (Your PDU is 20a, but you must derate it to 80% - 16a. This transformer provides the isolation and provides 120/240V out to the bypass switch, so neither of the two issues described above are relevant. So that'll double the current draw from your dual-feed max of 8a to a single-feed max of 16a. These power systems are 3-phase where … If you can specify how many BTU/Hr. On APC's site I am only seeing 208V to 120V step downs and they are in UPS units. Most public J1772 stations are 208v, so the cars have be compatible. Isnt most of Belgium or any super old Euro network 3x230 volts (230Y/133 no neutral). Is it possible to get two service drops … And 16a is as much as you got!Never neglect the derates and the halfsies if you value fault-tolerance and redundancy. That's because if you have a motor designed for 230V 50Hz and give it 60Hz, it spins 20% faster, but produces 17% less torque. I now know way too much (and too little) about power. running 1 208v or 240v circuit to your rack gives you 2 120v circuits. On the PDU outlet strips, try to plug teh first server into A-B, the second into B-C, the third into C-A, etc.You would typically have two power feeds (at least!) All our server room outlets go into a PowerWare 9390 UPS. What is the nature of the equipment. The power people are back and wiring up our server room, and yes I still have some more fundamental questions.My plan is to have 4 "dense" server racks. My initial thought was to feed a 120/240V panel through a center tapped transformer from the 120/208V panel, but the primary current on the transformer was like 900A which creates serious unbalance in my 120/208V panel. This external transformer has multiple input taps to allow you to supply it with 120/208V or 120/240V power, with the output set at 120/240V. 240V is the nominal service voltage rating. Tribus: Crotchety Old Bastard in Oklahoma City, http://www.apc.com/products/family/index.cfm?id=136. Three-phase 208 wye is a newer replacement for three-phase 240 high-leg delta. This is the case when all circuits will be 208v.For a three-phase with neutral, you are correct: 5 wires (the three "hots", one neutral, and one ground). Likewise, is 208v the same as 220v? In addition, you may be able to protect it with a GFCI, resulting in extra safety. Does it only say 208, or does it have a voltage range like 208-230? This could be useful to cut down the heat load in the room. That's industry standard. As you mentioned there are no cheap controllers for 240V. The 20 or 30 refers to the ampacity, and a trailing "R" or "P" indicates a receptacle or plug.A quick look at the literature shows the unit is probably a three-phase input with three-phase output of 208/120. Also a 240 Volt heater can use smaller gauge circuit wiring than a comparable size 120 Volt heater. Right now the way the server room is racked up it's pretty inefficent. 120v/208v single phase appliance wiring [ 2 Answers ] Recently purchased a coffee machine that has the above reqts. A 208V rated motor should not be run on 240V, nor should a 230V rated motor be run on 208V, motors rated 115/200-230V or 115/208-230V are fine either way, older 3Ø motors rated 220/440V will be fine on either a 208 or 240volt supply when connected for lower voltage. Look here: http://www.apc.com/products/family/index.cfm?id=136See the "208V 3-phase section"? Not enough voltage for the relay coils? In kilns smaller than 10 cubic feet, the lower wattage of 208 volts isn't an issue. The idea is based on the concept that 208V tends to be used in smaller facilities where the distance from service entrance to load is relatively shorter, so there is less voltage drop, and that true 240V 3 phase supplies tend not to drift upward very often or very much. I take it there is no way to have it in a simple PDU?Just stay with 120V?Everything we have is 120V right now. The IEC receptacles will usually be IEC C13, which is also … 240V/60Hz/3Phase power and 7.5KW .How can I make this work without killing the motor. Thanks again for everyone's input. I’d like to point out that you are asking 2 possible questions: Is the system you outlined, a) a 230V motor on a 240V supply? In parts of the world 240V Single Phase 2 Wire is the standard for homes. We've also go the Infrastructure Manager to monitor all the PDUs.Our electrican just loves the new gear compared to the old UPS that we had previously. 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