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Thread: 460V equipment in a 208V building- is a transformer worth the trouble?

  1. #1
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    460V equipment in a 208V building- is a transformer worth the trouble?

    we've got 208V 3 phase, and i have some equipment that is 460v. long story short- i got a screaming deal on the walkin, so if i have to trade the 460v compressor/condensors for 208/230 ones and a little cash im still pretty happy. but-- i've been seeing alot of used and decently priced glycol units that run ONLY on 460v.

    so- picking up a transformer wouldnt be the end of the world if i can find a decent unit for cheap.( or cheap-ish), even if it only ran the glycol and the walkin, because they obviously are the units that run 24/7 and pull the most amps.

    but i dont really understand the transformation process- if the 460v units run on half the amps of the 208/230 ones, that seems like it should save some utility costs, right?

    but we feed the transformer with only 208/230 from the street, and there's no such thing as a free lunch, so does this actually work to make a reduced power consumption scenario? or does the fact that we "feed" the transformer with 208/230 negate the "savings" from 460v's lower amp draw?

    curious to know if we could see savings that justify the cost of the transformer, or if i should just stick with 208/230.

    thanks

  2. #2
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    Utility companies charge by the kWh(kilowatt hour). You will not see an energy cost savings, see the math below. The units will use the same power at either voltage to do the work. The savings comes in the wiring, much smaller wires can be used at higher voltages.

    1 watt is equal to 1 joule/second of power use, not that important to know, but a good reference for trivia night. Volts are potential, think water stored in a water tower, lots of pressure the higher up it goes. Amps are how fast that water flows from the tower. kWh is simply how many kW you use in an hour, example: a 100 watt light bulb running for an hour uses 0.1kWh, a 1000 watt light bulb running for 6 minutes uses 0.1kWh, or 1kWh when on for an hour.

    To get kW from volts and amps in a 3 phase system: kW=(1.73 * volts * amps)/1000
    so for your system: since you didn't list the amps, I will make them up. (1.73 * 460 * 50)/1000= 39.8kW @460V, (1.73*230*100)/1000=39.8kW@ 230v

    These calcs are for ideal, purely resistive loads, inductive loads like motors and transformers have losses, so there will be more power used for the transformer to shift the voltage than just having 460v service straight to the compressor.

    Getting the higher voltages for other equipment, like pumps, compressors, heating elements is great, it reduces the size of wire required and also the size of conduit for it. Much savings to be had there.

    Hope this clears things up.

  3. #3
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    Quote Originally Posted by brain medicine View Post
    we've got 208V 3 phase, and i have some equipment that is 460v. long story short- i got a screaming deal on the walkin, so if i have to trade the 460v compressor/condensors for 208/230 ones and a little cash im still pretty happy. but-- i've been seeing alot of used and decently priced glycol units that run ONLY on 460v.

    so- picking up a transformer wouldnt be the end of the world if i can find a decent unit for cheap.( or cheap-ish), even if it only ran the glycol and the walkin, because they obviously are the units that run 24/7 and pull the most amps.

    but i dont really understand the transformation process- if the 460v units run on half the amps of the 208/230 ones, that seems like it should save some utility costs, right?

    but we feed the transformer with only 208/230 from the street, and there's no such thing as a free lunch, so does this actually work to make a reduced power consumption scenario? or does the fact that we "feed" the transformer with 208/230 negate the "savings" from 460v's lower amp draw?

    curious to know if we could see savings that justify the cost of the transformer, or if i should just stick with 208/230.

    thanks
    Jebster answered most of this, but I wanted to add that you will not only fail to enjoy savings by using the transformer, quite the opposite will occur. Transformers are not 100% efficient, so you will actually use more power this way, due to the losses in transforming 208 to 460.

    Many motors are designed to run on multiple voltages, though, so I'd first check to see if the compressor motor can be rewired for 208V wye. The fans may need to be replaced, but they also might support both voltages. Be sure to check to make sure the control panel can be switched as well. They sometimes have a transformer in them as well--it would need to be reconnected for the lower voltage.

    Regards,
    Mike Sharp

  4. #4
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    ok, so i was sort of right. no free lunch. no use going 460v it seems.

    i have always seen units that have multiple voltages- 208/230 and then another rating at either 360ish or 460ish. but oddly enough, these units do not have multiple voltages listed- which is why i entertained the idea of the transformer. and then i noticed some larger glycol units only have 460v. i assumed everything 3phase was multiple voltage...

    the plates on the equipment- only 460v is listed.

    i could contact the manufacturer and ask them if it can be used 208/230, but i'd also be worried about the conversation with the electrical inspector asking why im using a different voltage than what's listed on the UL plate.....

  5. #5
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    Quote Originally Posted by brain medicine View Post

    the plates on the equipment- only 460v is listed.
    If the motor only says 460v, this probably means it can't be rewired. It must be a really big glycol unit. How many horsepower?

    You should be able to sell it, though.

    Edit: While it still could be run off a transformer, if it's a big unit, then it will take a large transformer, and I suspect the cost of a suitable transformer will exceed the cost of another glycol unit, minus the sales price of this one.

    Regards,
    Mike Sharp

  6. #6
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    If you were building a new plant and installing new electrical infrastructure, then adding the 460v3p service may save you money on wiring and panels for certain things such as coolers, 277v lighting, and filters or pumps.. You would also want 208v3p service for pumps, brewhouse and all, but most of that can go 460v also. Also, need to keep 120/240 vac for household current.
    Todd G Hicks
    BeerDenizen Brewing Services
    Serda Brewing Company
    (Brewery-In-Construction) - Finally!!!

  7. #7
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    i think the main issue is right now we only have 200, so it will be an expense to bring 400 over here. since we lease and dont own, i would tend to think it might not be worth the trouble. i'd have to get the utility to give me an answer, which is like pulling teeth.

    the walk in coolers were 460v on the mechanical, probly why i got it so cheap. and i've seen some big used/refurb 10+ hp glycol units that are 460 only as im looking around, which made me ask the question. prochill spec'd us out at 120 to 150kbtu/h which is a fairly large unit for a brewpub. that's for two 30bbl cones and three 15s, and since we make mostly lagers, likely a dual stage HX. seems high to me, but thats what their math says.

  8. #8
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    A note about your glycol chiller sizing. This is not something that you want to way oversize. You can bake a little room for growth in there, but many of these systems will not run well when they are less than 50% utilized as far as cooling capacity goes.

  9. #9
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    im aware. but the calcs seem to suggest that we have a huge cooling load due to the HX dual stage- and that's only using a 60F temp for lagers. the math looks clear on their calcs, but it still seems like a massive load they're calling for and i cant come up with a reason why it seems too high other than just a gut feeling.

  10. #10
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    The best solution for your situation would seem to be a dual-compressor set up. We run a Prochiller with two 12 hp compressors (condensing units, actually). This allows the machine to run just one comp. when load is low, adding in the other when demand is high. I switch the lead comp. monthly, so both get the same run-time.

    While not completely redundant, this does give some back-up in case one comp. fails.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  11. #11
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    Dual compressors are good for this sort of thing as timm said. Another option is to have a larger reservoir of glycol that is used as a surge tank during high demand periods, or deactivate cooling to the tanks while you're chilling so that you do not warm anything up.

  12. #12
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    im definitely on board with a dual unit if i can find a decently priced system. the big load is really only coming at us when we knockout and need dual stage on the HX. so a dual unit should save us on power bill when we're just using one unit for cooling the conicals, which will be the majority of the time in a brewpub setting.

    i've considered just letting the groundwater bring it down to 70ish and then letting the fermenter drop towards mid 50s overnight, but realized that when its time to do double batches of the most popular beers, that might not work very well.

  13. #13
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    Our chiller has no problem doing this in an hour, we double batch our pils, turn the cooling on as we fill the first 10bbl, by the time the second batch is running off were below 55, so it brings it back up. We are at pitch temp by the time were done cleaning the kettle.

  14. #14
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    jebzter- whats the size/rating on your chiller unit? in SF we usually have pretty cool groundwater, low to mid 60s at most. i'd assume we should be able to get the wort down to mid 70s most of the year, maybe closer to 80 in summer. but they still have me needing a 120-150k /hour unit.

    maybe i overestimated what i'd need on the little brewery/glycol survey they have you fill out. seems like a hell of a lot of cooling. the math seems ok, but im wondering if i just gave a bunch of half-ass crappy assumptions about our usage, and now im getting a system that might be too big.
    Last edited by brain medicine; 05-19-2017 at 05:47 PM.

  15. #15
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    We have a ~60kbtu/h unit that keeps the glycol 28-32F. It runs our cold room(25'x12'x12'), 4x 10bbl fv, 4x20bbl fv, 2x10bbl brite and 2x20bbl brite. We can't crash all the tanks at the same time, two actively crashing, and then the rest holding at temp is done easily. The 20bbl tanks take the longest at about an hour to get to 55 from our knockout at 70. A few times a year the ground water isn't quite cold enough, and we get in the tanks at 75, so it takes an hour and a half at most. In the winter, I have to slow the cooling water down for our ales so we do not get too cold.

    The biggest single user of cooling will be your wort hx. You have a few options, pipe glycol into it or pre-chill your water. If you pipe the glycol to it, you first cool with city water, then with glycol. You can either have your chiller able to handle all of the tank load plus the hx, or the highest single load of either the cellar or the hx. You would turn off cooling to the tanks during knockout so that they don't warm up. The other option is to put a cold liquor tank in, chill that water down to say 40F, and use it for the hx water. You could also have a large(I would think 5 bbl would be enough) glycol reservoir. That would work as a surge tank, where you store up a bunch of cold glycol and use it, the whole tank will not warm up as fast since there is lots of cold stored up. Then it cools back down over say 2 hours before the next knockout. It comes down to really high stress loads, or you essentially bank cold water and then use it to chill, then rebuild it over a longer period.
    Last edited by jebzter; 05-22-2017 at 10:46 AM.

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