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Creating a "flexible" appliance power scheme

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Actually appliances like dryers don't even include a cord anymore. They have a small rear panel with a terminal block. Installing (and buying) the cord has been outsourced. To the customer!
Yes and most big machines have no cord eather and if thay do thay come with a pre install spec sheet for the receptacle needed. Andy
 
220 is long gone in the US. 240/120 is now the standard for residential. The 240 is from a center tapped transformer on the secondary where the center tap becomes the neutral. 3 phase residential is available, but extremely rare.

It's customary not to load a circuit more than 80% for "continuous" loads. A loose definition is loads that are expected to be on for 3 hours at a time. Certain loads are automatically designated "continuous" such as space heating.

Authough it's not customary to fuse the neutral, I had ONE piece of equipment that did within the equipment. It used a 3 phase 208, 100 A power source with Neutral and ground.

4pyros said:
The 4th wire is the return for 110 volt stuff but you can only do that up to a certain percentage of the total load. In a clothes dryer the 110 V load is vary small. If you put to much load on just one leg of the 220VAC then you will have to over rate the whole input.

In a 240/120 single phase system, the neutral conductor carries the difference of L1 and L2 and can flow in either direction. If L1=5 A and L2 =10 A then N = L2-L1 or +-5A depending on the sign convention. Analysis of the circuit usually assigns a sign relative to ground/neutral.
 
Currently we do use buck/boost transformers, but I would like to get rid of them entirely. Hence my desire to be able to get 120V from both 240 split phase and 208 single phase.
Some of the other challenges are that at 50hz, the motors run hotter (even though they are rated for 50hz) and the solenoids run hotter also. Typically at 50hz, we
run the solenoids at 100V.

I've been looking into DC, but DC motors are less efficient, and for solenoids with DC coils the MOPD ratings are reduced. This may turn out to be the best option though.
 
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Then have power specified that it requires the neutral. I don't think that's a big deal unless someone does something stupid like have the wrong people specify the power. We moved buildings from 240 to 208 4 wire and all of the plugs were 3 wire when we moved in. OOps.

That's OK. The way the contractor poured an isolated pad is that they poured everything and then broke up the isolated pad portion and then poured it.

With DC solenoids, it's best to use specialized drivers for them. I actually used PWM to control a solenoid that had to be activated for nearly a minute on and a minute off daily. I did it primarily to keep the big vibrations off an expensive spectral shaping glass filter. The PWM method worked really well. I've also used the kick and idle method for rotary solenoids.

Look into brushless DC.
 
That's OK. The way the contractor poured an isolated pad is that they poured everything and then broke up the isolated pad portion and then poured it.

OOps... The isolated pad was supposed to be thare!!!
 
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