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Apple CEO Tim Cook said that his company will start a $1 billion fund to promote advanced manufacturing jobs in the United States.
"We're announcing it today. So you're the first person I'm telling," Cook told "Mad Money" host Jim Cramer on Wednesday. "Well, not the first person because we've talked to a company that we're going to invest in already," he said, adding that Apple will announce the first investment later in May.
[...] As advanced manufacturing jobs are in high demand in the U.S., the sector was already high on Apple's list of priorities, and Cook hopes the investment will spur even more job creation.
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Apple Just Promised to Give US Manufacturing a $1 Billion Boost
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(Score: 2) by VLM on Tuesday May 09 2017, @12:35PM (3 children)
One that throws me off is 440
Something to do with 440 delta (across phases) is 277 wye (any of 3 hots to the neutral) and you can get cheap industrial light fixtures for 277 so more wattage / lower voltage drop for a huge office lighting load.
Why not install 440 fluorescent ballasts? My guess is 277 ballasts are a minor change from 220 ballasts but 440 ballasts would take a whole new assembly line. Yet I've also been told 277 is high enough that they won't work on 220 home circuits so as to discourage employee theft. And at the same time Home Depot etc sells universal ballasts that don't care feed in anything from 120 to 277 and they're happy. I don't see universal voltage ballasts that go from 120 to 480 although from a purely technical EE perspective that wouldn't be too hard my guess is regulatory red tape, and they probably do exist.
high leg delta system
For the non-electrically inclined this is ground and neutral the center tap of one phase of a 240 delta 3-ph service and from the center tapped neutral to the opposite hot is 208 volts single phase. Why, I donno, because you could run across any two hots and get a single phase of 240 so why run 208? My guess is some kind of current limitation where throwing across one phase puts all the current on two wires possibly exceeding voltage drop/thermal limit but going 208 would load all the phases about equally badly, maybe probably kinda so you get more watts out of the same pieces of copper, assuming you were not using that 3phase drop for anything else. Every time I've seen something weird with 3-phase its always handwaved away with some "balancing the phases" stuff.
(Score: 2) by LoRdTAW on Tuesday May 09 2017, @02:25PM (2 children)
We're going off topic big time but I enjoy discussing the topic.
Today The POCO's (power companies) today have all standardized to ANSI C84.1 and deliver 120/208 or 277/480 wye (except Con Edison who insists on still serving 265/460 for some dumb reason). In Canada they still may provide 346/600 wye but I can't be certain.
Delta service is obsolete for all new construction unless you have a really good reason for requesting it at the approval of the POCO. The only exception to that is if you are fed from an existing 240V high leg service which is still pretty common in older industrial areas. Out here on Long Island there are still pockets of 240V high leg delta all over. Our current facility was built in 1982 and is fed from a dedicated 500kVA 120/208 transformer to a 1200 amp switch board. Our old building up the road is in an old industrial area built in the 50's which is still fed from a 240V high leg delta pole network on the block.
440 delta is an old obsolete service which some people still use to refer to 480V. This is where the confusion comes in. It is a multiple of the old 110V standard. There still may be some 440V delta systems out there but limited to existing systems which have been in place for decades. You will not find a new 440V delta service installed anywhere. They were also commonly ungrounded as a delta transformer has only three connections with full line voltage across all of the terminals. Though there are two methods to derive a ground: corner grounding and transformer grounding. Corner grounded means they take a phase and ground it. That phase is now at earth potential. The problem with that system is there is a large amount of capacitive coupling between the two unearthed phases and the earthed phase. This causes problems in motors as the windings capacitively couple to the earthed casing causing them to run hotter. Not a popular method and currently not allowed by the NEC unless it is an existing system which is grandfathered in. Transformer grounding is achieved with the zigzag transformer or a wye-delta transformer. Going into technical detail is out of scope for now but those methods were actually less common and they left those systems ungrounded. Why? High reliability. If a line-earth short occurs, a breaker could trip causing down time. Instead they installed a ground detector at the switchboard which was a set of three lamps connected wye with the center point of the wye grounded. During normal operation the bulbs glowed at equal brightness. If a phase shorted to earth, the set of bulbs on the corresponding shorted phase would dim or extinguish. The plant electrician would then trace the short while the machines kept on chugging along.
Today they use what's called an HRG or high resistance ground. There is a current limiting resistor placed between the center neutral point of a 277/480V transformer and ground. This is used to limit line-earth short circuit current to about 5 amps. A ground detector is simply a current sensing relay that closes when current is detected across that resistor which alerts the user to the short. A pulser is then turned on which is a timer relay that turns on and off switching another resistor in parallel or series changing the short circuit current every second or so. The plant electrician then goes around with an amp meter looking for the wires which are carrying the pulsing current to the short eventually tracing it down. Ungrounded deltas can be retrofitted with HRG's using grounding transformers with the same resistor and pulser setup. The only catch with an HRG is you cannot have line-neutral loads for safety reasons defined in the NEC.
Delta and wye are two different transformer connection methods. There is no 277 available from a 440 or 480V delta transformer. Only way to get a neutral from a delta is by using a zigzag or wye-delta grounding transformer. Though, if true 277/480 wye were needed from a 440 or 480 delta service, a properly sized transformer would be used to create a separately derived 277/480 system. That's the proper way to do it according to the NEC. And it is the only way you can safely derive single phase 277V from a wye HRG, corner grounded delta, or ungrounded delta service (it has to be isolated).
Delta was popular because it can tolerate losing one of three transformers at the cost of 43% of the systems output. That's called open delta which can deliver full three phase power from just two sets of windings instead of three. You are limited to 57% of the total nameplate rating of the both transformers (e.g. two 10kVA transformers in open delta can only supply about 11.4kVA, not 20kVA). Popular in rural areas for farmers who only need a small amount of three phase power to run irrigation pumps. Sometimes called poor man's or farmers three phase. Though I see it here on long island supplying gas stations and small stores that have three phase refrigeration. If a transformer fails in a wye, you lose three phase completely. Though, motors will continue to run but they will burn out as they are self generating the missing phase at the cost of higher input current.
277V lighting is popular in 277/480 facilities because it can supply more power per amp reducing wire sizes and eliminates the need for a stepdown transformer. Why only 277 and not 480V? Because of the NEC. It dictates that a lighting fixture must only be served from a single live phase with respect to ground. This is why you don't see 480V ballasts or LED lighting. Both phases are live with respect to ground. 277V is a single phase grounded supply.
(Score: 2) by VLM on Tuesday May 09 2017, @04:37PM (1 child)
440 delta
Whoa. I was thinking wye.
It dictates that a lighting fixture must only be served from ... with respect to ground.
I guess in retrospect I brain faded a bit because very few "light switches" are double pole, and the lifespan of the average light bulb changing office drone relies on a single pole switch being able to remove all the hot from a fixture while replacing a bulb.
I'm gonna guess the NEC would not be amused by running 220V lighting in a residence relying on multivoltage ballasts and only switching one of the hots. In fact I'll go further and suggest this is why my oven has a 110V lamp instead of a 220V because its too easy to touch a hot phase especially if one pole a a dual pole switch/relay broke.
Though, motors will continue to run but they will burn out as they are self generating the missing phase at the cost of higher input current.
Yeah generations of home machinists have set up a large idler motor with nothing connected (maybe a flywheel) and hook up like one phase and parallel the 3phase to your lathe or whatever and pull a rope or something dangerous to get the idler spinning and generating your 3-phases off one. Quite inefficient and sorta dangerous but it works. It sells well to the "Dynamotors are too expensive and reliable" crowd. Now a days people use the $200 VFD, feed in whatcha got and out comes anything you want, more or less.
(Score: 2) by LoRdTAW on Tuesday May 09 2017, @07:32PM
If you're really lucky and fed from a three phase 120/208 wye, you can get three phase out of it with just two transformers. In New York City Con Edison feeds many homes from a 120/208 wye. The thing is, you only get two of the three phases. This is called open wye and you can't directly run a three phase motor from it unless you set up an idler. BUT, if you draw a wye connection, eliminate one of the legs and turn it sideways, it looks an awful lot like an open delta because it actually is. It's a 120V open delta which is wired backwards with respect to delta polarities. So you grab two 120->240V transformers and wire the 120V legs in the same open wye polarity, the H1 of both transformers each to to a hot leg and the two H2's go to neutral (H terminals are primaries, X are secondaries). Now on the 240V side you wire the X2 of the first to the X1 of the second as if in series. Now you have a properly configured 240V open delta at X1a, X2a+X1b, X2b. Full three phase from an open wye service without any idler motors or capacitor starters. No ground unless you corner ground but I would rig up a light bulb ground detector and call it a day. Of course the same derating applies of about 50% of the total nameplate kVA. And your input is only 120V so you have to multiply your load by two to size the input breaker; e.g. a 20A load draws 40A at the input.
You can even get full 120/208 wye if you use transformers with two 120V secondaries. One 120V secondary winding on each transformer forms two of the phases and the second pair on each transformer is wired in series to get the third phase. Connect all the commons for a neutral and you're up and running with a full 120/208 wye. Again the derating applies.
POCO's do this in rural areas where farmer joe is a ways from the primary distribution lines. So instead of dragging a full set of four lines from their medium voltage network, they run two phases plus neutral and set up an open wye to open delta on the pole. They save money by eliminating the extra wire. If you search for open wye open delta you can find utility transformer connection diagrams. They can even supply full 120/208 from an open wye primary using the same trick above.
Of course, my home is part of a small 240 center tap network and the next block has 120/208. Very frustrating.
As for the goofy idlers, I've seen setups have a small belt coupled single phase pony motor to spin up the idler. Some setups use a capacitor starter on a timer or momentary button. The cap starter simply connects a cap from one of the lines to the third phase to create a out of phase wave to get the motor to start turning. I believe the derating is something like 2/3 nameplate horsepower or less.
And lastly, VFD's are the way to go if you only have 240V split phase. Automation Direct carries a few that can operate off single phase up to 3HP for a little over $300.