4 Wire Wye Vs 4 Wire Delta - New Construction

[Besoeker]

Metric, not decimal, of course. Brain fart.

Och mon, it happens to the best of us....

Metric or, more accurately, SI has many advantages over Imperial units. One is that there are far fewer units. One of the advantages is that there are far fewer units.
Take length for example. Inch, foot, yard, furlong, mile, league. Not to mention link, chain, fathom etc.
In the SI system the basic unit is the metre. It is actually the only unit. Of course there are multiples of it appropriate to what is being measured - mm, km for example. You don't have to remember conversions like a mile being 1760 yards.

I often do conversions between the systems. My wife is American and likes to cook. Many of her recipes are in Imperial and I do the converting when required.

 

[ggunn]

Och mon, it happens to the best of us....

Metric or, more accurately, SI has many advantages over Imperial units. One is that there are far fewer units. One of the advantages is that there are far fewer units.
Take length for example. Inch, foot, yard, furlong, mile, league. Not to mention link, chain, fathom etc.
In the SI system the basic unit is the metre. It is actually the only unit. Of course there are multiples of it appropriate to what is being measured - mm, km for example. You don't have to remember conversions like a mile being 1760 yards.

I often do conversions between the systems. My wife is American and likes to cook. Many of her recipes are in Imperial and I do the converting when required.

... and then there are the gawdawful bastardized decimal inches. D'oh! I hate them so much!

 

[Besoeker]

... and then there are the gawdawful bastardized decimal inches. D'oh! I hate them so much!

SI avoids that.
You already use amps, volts, watts. SI units. There are no Imperial equivalents. So, why not go the whole nine yards and be all SI?

 

[winnie]

SI might avoid bastardized units, but 'the metric system' is full of them.

How many times have you seen a pressure gauge with 'kg/cm^2' as the unit?

Or a speed limit given in 'km/hr'

How about temperatures in C?

Personally, I'd be game for a 'unified system of units' where the unit of length made the speed of light exactly 10^9 units per second

-Jon

 

[Besoeker]

SI might avoid bastardized units, but 'the metric system' is full of them.

How many times have you seen a pressure gauge with 'kg/cm^2' as the unit?

Or a speed limit given in 'km/hr'

How about temperatures in C?

Personally, I'd be game for a 'unified system of units' where the unit of length made the speed of light exactly 10^9 units per second

-Jon

Here pressure is usually given in Pa. It's Newtons per square metre.
Speed limits in continental Europe are usually on a round sign with just a number. For example in France 110 is common. It's 110 kph which is close to 70 mph. The speedometer in my car displays both.
In, the car, also displays temperature in degrees C. I have a weather station in the garden. That's also in degrees C

 

[Smart $]

SI avoids that.
You already use amps, volts, watts. SI units. There are no Imperial equivalents. So, why not go the whole nine yards and be all SI?

A little satire thrown in there for the fun of it??? ... :lol:

 

[mbrooke]

For most of the applications I deal with, 3-phase industrial, there is a requirement for a contactor and an isolating switch.

Correct, and switches is one place where a re-design is needed.

It could but I think the probability of it doing so is relatively small.

Im leaning toward one day it will happen.

I rarely come across them so I can't comment

But they are smaller and lighter.

Polyphase on a washing machine? All of those that I've encountered have been single phase. Admittedly it isn't that many.

No, the motor is 3 phase, not the supply. Most inverter driven appliances like the fridge use a 3 phase motor. An inverter fed 3 phase motor is the most efficient.

My point was about relative costs.

As time goes on the cost will break even. It has already done so for wall warts and computer chargers.

 

[ggunn]

SI avoids that.
You already use amps, volts, watts. SI units. There are no Imperial equivalents. So, why not go the whole nine yards and be all SI?

In engineering school I did. In "real life" dealing with construction types in the US, not so much.

 

[ggunn]

SI might avoid bastardized units, but 'the metric system' is full of them.

How many times have you seen a pressure gauge with 'kg/cm^2' as the unit?

Or a speed limit given in 'km/hr'

How about temperatures in C?

Personally, I'd be game for a 'unified system of units' where the unit of length made the speed of light exactly 10^9 units per second

-Jon

Actually, what I meant by "bastardized" was the mixing of decimal fractions of inches with 12 inches to the foot, etc. Decimal inches is easier to calculate, but when drawing up plans having to figure out how many 16ths of an inch is equal to 0.8876 inches (or whatever) is a pain. Yes, I know how to do it, but it's still a pain.

 

[winnie]

Just for you, I try to use 'dodecameter' as a unit of length

-Jon

 

[ggunn]

Just for you, I try to use 'dodecameter' as a unit of length

-Jon

... and for velocity I use furlongs per fortnight.

 

[iceworm]

...Then again when DC takes over it will be a mute point.

DC already took over - then gave it back. you're thinking it will try again?

ice

 

[mbrooke]

DC already took over - then gave it back. you're thinking it will try again?

ice

The technology back then made DC of almost every kind impractical. Further loads were almost always motor, ballast or restive two of which required AC for practical efficiency and the other did not care. Power was generated in bulk at one end and consumed at the other unlike today. With technology changing the pendulum is swinging in the other direction.

 

[ggunn]

The technology back then made DC of almost every kind impractical. Further loads were almost always motor, ballast or restive two of which required AC for practical efficiency and the other did not care. Power was generated in bulk at one end and consumed at the other unlike today. With technology changing the pendulum is swinging in the other direction.

I don't see DC overtaking AC for grid power any time soon. Transformers for voltage conversion are much easier than DC to DC conversion, and there is too much AC equipment out there to change to DC.

 

[iceworm]

The technology back then made DC of almost every kind impractical.... .

Just goofing with you - not particularly serious.

Tell me how the current technology does with DC circuit breakers. I don't see DC doing much different than today. There still are not any decent DC CB available. Truly, have there been any breakthroughs since 1880? I think magnetic coils and puffers have been around about that long.

No, I'm not quite that old. I am older than rocks - but I am younger than sand. But I have read a few history books.

ice

 

[mbrooke]

I don't see DC overtaking AC for grid power any time soon. Transformers for voltage conversion are much easier than DC to DC conversion, and there is too much AC equipment out there to change to DC.

Maybe not in the next few years, but give it decades and the process will be in motion. As I said, DC transformers are still more expensive today, but I can see that changing. The break even point in HVDC is decreasing every day. Biggest drive behind DC will be renewable energy.

 

[mbrooke]

Just goofing with you - not particularly serious.

Tell me how the current technology does with DC circuit breakers. I don't see DC doing much different than today. There still are not any decent DC CB available. Truly, have there been any breakthroughs since 1880? I think magnetic coils and puffers have been around about that long.

No, I'm not quite that old. I am older than rocks - but I am younger than sand. But I have read a few history books.

ice

Semiconductor breakers. In the very least the converters can begin forcing "artificial zero crossings" and let a regular breaker do the rest.

 

[iceworm]

Semiconductor breakers. In the very least the converters can begin forcing "artificial zero crossings" and let a regular breaker do the rest.

I'm not familiar with "semiconductor breakers". Who is making those?

As for the 'converters forcing "artificial crossings"', are you looking to use a switching power supply to change the DC to HF AC the use a CB?

Are both of these in production or "soon to be"?

ice

 

[mbrooke]

I'm not familiar with "semiconductor breakers". Who is making those?

As for the 'converters forcing "artificial crossings"', are you looking to use a switching power supply to change the DC to HF AC the use a CB?

Are both of these in production or "soon to be"?

ice

Ill put it this way, can the current IGBTs used in HVDC stop conducting completely? Imagine the same concept for fault currents.

 

[iceworm]

Ill put it this way, can the current IGBTs used in HVDC stop conducting completely? Imagine the same concept for fault currents.

Absolutely imagineable. I'm a little bit familiar with Rockwell's IGBT frontends on their MV drives. For 500A, six hockey puck sized semiconductors stacked up to make 6600V on each bridge leg. Add a water/glycol cooling system with an outside radiator, to keep them alive anytime the current is going through them. Two 3' x 3' x 6' cabinets for a 500A CB. hummmm......Concept is great, but consider a 1200A SF6 MV CB ~ 3' x 3' x 3'.

That is why I'm asking: Is anyone making DC CBs using different technology than that available in the 1880?

ice