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Old 08-30-2018, 04:09 PM   #6461
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Originally Posted by Cowracer View Post
At zero speed the motor will make its most torque, and also use the most amps. This is called "locked rotor amps" and is usually about 400 times the amp draw at full load. It can be quite alarming watching the amp draw on a motor starting a heavy, high inertia load like a big fan or pump. Any electric motor will gleefully make many times its rated horsepower.Tim
Thanks for the write-up. Based on posts on A/Cs, I've wondered for a while what LRA was, but have been to lazy to look it up...
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Old 08-30-2018, 04:24 PM   #6462
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This gem wasn't in a camp but towed into the shop today. It hasn't ran in 4 years. After cleaning wasp and rat debris from the air filter and some new batteries she fired right up. That's a chevy for you.
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Old 08-30-2018, 04:25 PM   #6463
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This gem wasn't in a camp but towed into the shop today. It hasn't ran in 4 years. After cleaning wasp and rat debris from the air filter and some new batteries she fired right up. That's a chevy for you.
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Old 08-30-2018, 04:33 PM   #6464
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Originally Posted by Cowracer View Post
Theres no substitute for cubic amps.

Ok, in every engineer there is a frustrated teacher just dying to get out, so heres one chance for me.

Electric motors are ideal for pulling heavy loads. That's why all locomotives use them as the final drive. Due to its design, electric induction motors produce their maximum torque at zero speed. Just perfect for getting a heavy load moving. Torque decreases as the motor speeds up, approaching zero torque at synchronous speed.

Synchronous speed is a function of frequency (Usually 60 hz in the US) and the number of poles in the motor. The math boils down to 120x60 (freq)/number of poles. A motor can only have even numbers of poles, so a 2 pole motors sync speed is 3600rpm. A 4 pole is 1800, a 6 pole is 900 and on and on. Were you to energize a motor with no load on them, they would run at that speed and produce zero torque. Of course, with zero torque, any load applied to them will slow the motor down. As it slows down, torque is produced and at some point the load and torque will balance. The nameplate of the motor will list it speed at it's rated horsepower. Usually a 4 pole motor will run somewhere around 1730rpm. The difference between the sync speed and the actual speed at rated HP is called slip and is determined on how the motor was made. That speed is solid. You can't vary the speed by changing voltage. Like I said, its a function of how the motor was made, and the frequency of the power coming into it. So how do you vary the speed? A neat little device called a Variable Frequency Drive (VFD) that bacically converts the incoming 60hz AC into DC, then forms that DC back into AC and whatever frequency you want. Vary the frequency, vary the speed. They make a distinctive, high pitched noise when running. I've worked with them enough that I can tell if a motor is VFD controlled or not just by standing by it.

Torque and Amps are practically interchangeable in an induction motor. As you add load, the motor slows down from synchronous speed, torque is generated and the amps go up. At rated load, the expected amp draw is called Full Load Amps (FLA) and is listed on the nameplate of the motor. At zero speed the motor will make its most torque, and also use the most amps. This is called "locked rotor amps" and is usually about 400 times the amp draw at full load. It can be quite alarming watching the amp draw on a motor starting a heavy, high inertia load like a big fan or pump. Any electric motor will gleefully make many times its rated horsepower. The only limit is for how long. A starter motor in your car might make 15HP but only for 30 second at a time before it overheats. It is very small, weighing in at about 25 pounds. A 15 HP industrial air-cooled motor rated for continuous use weighs about 270 pounds. Tesla motors are more powerful and lighter because of advanced cooling practices.

Tesla's are cool, but the car i admire the most is the Chevy Volt. It's a true hybrid, meaning that the ONLY motor driving the wheels is the electric one. The gas engine only runs a generator, providing power to the traction motor and charging the batteries. That is pretty much how a diesel-electric locomotive runs and I bet you will see a LOT of 'electric' cars coming with a small gas engine/generator in the future.

Tim
Good info to a point. I love my Volt but when on gas it does not put a charge back into the battery.(main drive battery) Only time battery gets a recharge is if on a down hill descent it will then put a slight charge back into the battery. Later RJD
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Old 08-30-2018, 04:33 PM   #6465
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Things you see in an RV Park

Mystery solved for two of the buses here at Normandy farms for two of them. Prevost, Bubba Watson and family. Newell, Jason Day and family.
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Old 08-31-2018, 08:16 AM   #6466
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Originally Posted by CZNEDY View Post
Mystery solved for two of the buses here at Normandy farms for two of them. Prevost, Bubba Watson and family. Newell, Jason Day and family.


Good detective work!
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Old 08-31-2018, 08:25 AM   #6467
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Originally Posted by Cowracer View Post
Theres no substitute for cubic amps.

Ok, in every engineer there is a frustrated teacher just dying to get out, so heres one chance for me.

Electric motors are ideal for pulling heavy loads. That's why all locomotives use them as the final drive. Due to its design, electric induction motors produce their maximum torque at zero speed. Just perfect for getting a heavy load moving. Torque decreases as the motor speeds up, approaching zero torque at synchronous speed.

Synchronous speed is a function of frequency (Usually 60 hz in the US) and the number of poles in the motor. The math boils down to 120x60 (freq)/number of poles. A motor can only have even numbers of poles, so a 2 pole motors sync speed is 3600rpm. A 4 pole is 1800, a 6 pole is 900 and on and on. Were you to energize a motor with no load on them, they would run at that speed and produce zero torque. Of course, with zero torque, any load applied to them will slow the motor down. As it slows down, torque is produced and at some point the load and torque will balance. The nameplate of the motor will list it speed at it's rated horsepower. Usually a 4 pole motor will run somewhere around 1730rpm. The difference between the sync speed and the actual speed at rated HP is called slip and is determined on how the motor was made. That speed is solid. You can't vary the speed by changing voltage. Like I said, its a function of how the motor was made, and the frequency of the power coming into it. So how do you vary the speed? A neat little device called a Variable Frequency Drive (VFD) that bacically converts the incoming 60hz AC into DC, then forms that DC back into AC and whatever frequency you want. Vary the frequency, vary the speed. They make a distinctive, high pitched noise when running. I've worked with them enough that I can tell if a motor is VFD controlled or not just by standing by it.

Torque and Amps are practically interchangeable in an induction motor. As you add load, the motor slows down from synchronous speed, torque is generated and the amps go up. At rated load, the expected amp draw is called Full Load Amps (FLA) and is listed on the nameplate of the motor. At zero speed the motor will make its most torque, and also use the most amps. This is called "locked rotor amps" and is usually about 400 times the amp draw at full load. It can be quite alarming watching the amp draw on a motor starting a heavy, high inertia load like a big fan or pump. Any electric motor will gleefully make many times its rated horsepower. The only limit is for how long. A starter motor in your car might make 15HP but only for 30 second at a time before it overheats. It is very small, weighing in at about 25 pounds. A 15 HP industrial air-cooled motor rated for continuous use weighs about 270 pounds. Tesla motors are more powerful and lighter because of advanced cooling practices.

Tesla's are cool, but the car i admire the most is the Chevy Volt. It's a true hybrid, meaning that the ONLY motor driving the wheels is the electric one. The gas engine only runs a generator, providing power to the traction motor and charging the batteries. That is pretty much how a diesel-electric locomotive runs and I bet you will see a LOT of 'electric' cars coming with a small gas engine/generator in the future.
Tim
One thing no one is talking about is that to produce an electric drive train, you need only 10% of the workforce you need to produce a gas/diesel one.
Masssive adoption of electric drivetrain will cause massive unemployment...
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Old 08-31-2018, 04:12 PM   #6468
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Those front tires are waaay off the ground.

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Old 08-31-2018, 04:14 PM   #6469
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Things you see in an RV Park

Looks like maybe flushing his tanks ?? I tilt mine to one side when flushing out and cleaning good at home.

But ya that way up here in the air.

Russell
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Old 08-31-2018, 04:26 PM   #6470
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[QUOTE=Cowracer;1915145]Theres no substitute for cubic amps.

Ok, in every engineer there is a frustrated teacher just dying to get out, so heres one chance for me.

This is called "locked rotor amps" and is usually about 400 times the amp draw at full load.
-----------

Like every engineer does with predictable frequency (including me), Cowracer missed the decimal point. Locked rotor amps is typically 4 times the full load running amps. That's 400%, not 400 times.
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Old 08-31-2018, 04:36 PM   #6471
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Looks like maybe flushing his tanks ?? I tilt mine to one side when flushing out and cleaning good at home.

But ya that way up here in the air.

Russell
No it was sitting like that for 3 days.
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Old 08-31-2018, 04:42 PM   #6472
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Probably went to the emergency room for his nose bleed...
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Old 08-31-2018, 04:45 PM   #6473
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One thing no one is talking about is that to produce an electric drive train, you need only 10% of the workforce you need to produce a gas/diesel one.
Masssive adoption of electric drivetrain will cause massive unemployment...
...not to mention the $250K per in subsidies on the Volt...
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Old 08-31-2018, 05:17 PM   #6474
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I wouldn't be worried about towing capacity as much as towing time...lol. A friend of mine drove his Tesla from NC to Nevada and said he had to pull over every 5'ish hours to recharge. SMH. The new Porsche Mission will get 80% charge in 15 minutes.

Might be great that the car drives by itself (he said he only drove 10% of the time, the car did the rest) but it would take forever to get anywhere...

Mark
& Assuming it did not make an Impromptu turn into the lane divider or a Firetruck parked on the shoulder
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Old 08-31-2018, 06:08 PM   #6475
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Old 08-31-2018, 06:43 PM   #6476
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Originally Posted by CZNEDY View Post
Mystery solved for two of the buses here at Normandy farms for two of them. Prevost, Bubba Watson and family. Newell, Jason Day and family.
CZNEDY.....

So we know your Berk is mingling right in with the other pushers (diesel that is)
but I don’t remember seeing you out on the fairways with Bubba and Jason.

Did you “birdie” “eagle” or any other avian terms on the golf course?
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Old 08-31-2018, 06:48 PM   #6477
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No it was sitting like that for 3 days.


Well that crazy angle. Never been on a site with that much slope. ??

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Old 08-31-2018, 06:56 PM   #6478
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Those front tires are waaay off the ground.

Ready for lift off Mr Spock Later RJD
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Old 08-31-2018, 07:01 PM   #6479
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I see three blocks under each jack so that "lift off" angle is definitely intentional...
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Old 08-31-2018, 07:04 PM   #6480
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Those front tires are waaay off the ground.

The KOA in Bar Harbor, Maine had sites that required that kind of lift just to get close to level. Alot of motorhomes were hanging the front wheels.
My site was so unlevel that our 5er hitch was too low to back under, the back bumper was almost 4' high, and the left side tires were completely off the ground, which I took advantage of and checked for bearing play.
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