Power Draw Question / 3 hp motor not turning

[Bobo_LaDouche]

Hi. I am stuck in the boondocks for a few weeks, and trying to figure out how to turn my 3 hp rock saw from my Tesla outlets. Nothing works, and I am not sure if anything will, but if there is any advice, please step forward…)

Saw motor: single phase, 3400 rpm, 120v, 60hz, 15-amp continuous draw, 25.5-amp peak draw – taken from the tag. Draw of current seems to not be true. Company: Germans Boda S.A., Italy.

Tesla CT plugs – from the Owner’s manual: 120 v plug is rated for 20 amp continuous and 40 amp peak. 240v plug is rated for 40 amp continuous and 110-amp peak.

Situation:
Motor works at 120v in a house circuit with 50-amp breaker, but not with a 30-amp breaker.

Motor does not work in CT with 110 breaker. Does not start to turn. When 240 v circuit is used, less one hot lead (120v configuration from 240v breaker), the motor starts to turn, but stops abruptly at 11,000 volt x amps (92 amps) draw, according to the screen in the vehicle that shows charging and power draw.

Can I make this saw motor work?

Why does the motor run with less than 50 amps in a house plug, but require more than 92 amps in the CT?

Is any of this correct?

I would appreciate some help if anyone has any ideas.

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[Edphonse]

So those saws have huge inductive loads in addition to large surge amperage on start up. AC power isn't as "simple" as DC power and ac power us actually broken up into 3 types of power; real, reactive (sometimes called imaginary), and total. The inductive load from that saw causes a lot of reactive power on that circuit and, based on how tesla described why you can't AC charge and use the outlets at the same time is because it uses the same circuitry that converts between ac and dc, which tells me that the ac output from the truck is a high frequency inverter vice a low frequency.

Low frequency inverters use large copper coils to generate its output (see victron energy inverters) and weigh/cost significantly more than hf inverters (such as EG4 inverters). My 5000 VA (basically about 4000 watts) victron inverters weigh about 75 lbs each while my eg4ll 6500s (6500 watts) weigh about 60 lbs, as I recall.

Now the reactive load shifts the power factor on that circuit and hf inverters don't work as well with poor power factors as a lf inverter. Your house doesn't care because the power plant feeding your house doesn't even register that little if reactive power. I suspect the CT inverter is overloading on reactive power and shutting down to protect itself.

This is purely speculation based on the indications you are seeing coupled with the fact that I have not seen a VA rating (or VAR rating) for the CT makes me suspect there is too much of a reactive load on the inverters. Chris Boden (I believe that's who did it) on yt did a fairly decent job imo on explaining how AC power actually works.

Tl;dr I think you might be overloading the reactive power the CT can supply.

 

[Bobo_LaDouche]

TY. I actually understand your explanation and appreciate that you made this clear; I feared it was something complicated like this, and it makes sense. I need another solution, rather than just moving wires around...)

 

[REM]

Can you not wire your motor up to accept 240v at lower amperage?

What's the model number?

 

[Bobo_LaDouche]

Can you not wire your motor up to accept 240v at lower amperage?

What's the model number?

This is the DX 350-N 1300, "52918", which is the 120v 60hz version.

Looks like the 56915 motor and the 5885 wires and recepticle.

 

[REM]

This is the DX 350-N 1300, "52918", which is the 120v 60hz version.

Looks like the 56915 motor and the 5885 wires and recepticle.

You may be in luck, as I think the motor for the 120v and 240v models are the same, it just depends on how you wire it up. Take a look at page 25:

https://s3.eu-west-3.amazonaws.com/...3-23-d5bbbbae-883c-11ed-9ad8-40ec99b41a18.pdf

I would call the manufacturer and ask for assistance understanding if the motor can indeed be wired to accept 240v. I know I converted a large dust collector of mine from 120 to 240, and of course it runs much better on the higher voltage and lower amperage.

 

[Bobo_LaDouche]

Interesting. Since the diagrams for 110v and 230v are the same (?), this means I just put double the voltage on the 1 line in, and it should work.... My 240v source is single phase also. I see why you recommend the phone call. We have 8,000 feet of rock to cut, and blowing the motor would put a real crimp in our style, in fact it might stop the operation... ) TY for taking the time to help.

 

[mongo]

Interesting. Since the diagrams for 110v and 230v are the same (?), this means I just put double the voltage on the 1 line in, and it should work.... My 240v source is single phase also. I see why you recommend the phone call. We have 8,000 feet of rock to cut, and blowing the motor would put a real crimp in our style, in fact it might stop the operation... ) TY for taking the time to help.

I think the wiring is the same but the motors (both saw and pump) are different.

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