PTO generator

[Rob-D]

Fred,
I won't give you that answer and here's why:
First, you should pay an engineer to do a work sheet for you. ... You want someone to be responsible for their calculations and I would say PM me and I'll give you an invoice..."<end quote>

OK, thanks Rob. My reason for asking was to get some free advice, without any professional liability. Most engineers overdesign at the expense of their clients to cover their own Errors and Omissions. I'm a risk taker, and I accept that. The generator salesman wants to sell me a unit three times bigger than I need. The fuel salesman the same. I'm a survivor, just trying to get by. When the goin gets tough, every ounce of fuel really counts. That's why I originally posted your quote. We live in a wasteful society and we don't even know it, until we run out what we need. Just like our country has run out of affordable health care, because doctors order a lot of unnecessary proceedures to cover their own liability, and guess who pays. So, back to the drawing board I go...(BTW, what would you charge me to design the smallest, minimalist, survivalist back-up system that only gets used a few days a year, with a discount for waived professional liability?)

Fred, thank you for asking but I'm semi-retired now, most of my work is in electronic engineering using embedded microcontrollers and several audio designs I promised an editor. Perhaps one of the people here who found my solution overly simplified might be inclined to address your issue but, again, a 25hp hydraulic elevator mandates a bonded legal responsibility in my view.

 

[fred239]

Thanks for the advice. I checked with the power company and "demand" does not measure peak surge, only the average of maximum usage in five minute increments. They recommended I measure with a pulse monitor; so I am still learning.

 

[joshuabardwell]

Thanks for the advice. I checked with the power company and "demand" does not measure peak surge, only the average of maximum usage in five minute increments. They recommended I measure with a pulse monitor; so I am still learning.

For less than $100 (on Amazon.com--more at your local big-box) you can get an "amp clamp" will answer this question definitively. Be sure to get one with an "inrush current" measuring feature that will detect and hold the peak draw from the motor.

 

[aczlan]

For less than $100 (on Amazon.com--more at your local big-box) you can get an "amp clamp" will answer this question definitively. Be sure to get one with an "inrush current" measuring feature that will detect and hold the peak draw from the motor.

For less than $10 at Harbor Freight you can get one that does the same: Digital Clamp-On Multimeter (note that you can only go over one leg of the wire going to the pump. If you go over both legs it doesn't read anything).

Aaron Z

 

[PineRidge]

This digital monitor comes with 4 wrap around clamps 2 large and 2 small. I clamped one around each of the incoming load legs from the meter. The probes then plug into the back of a small transmitter that will send the signal a couple of hundred feet to the receiver. It gives a read out in real time and stores a 2 year log I believe. The whole shebang is battery powered.

 

[aczlan]

This digital monitor comes with 4 wrap around clamps 2 large and 2 small. I clamped one around each of the incoming load legs from the meter. The probes then plug into the back of a small transmitter that will send the signal a couple of hundred feet to the receiver. It gives a read out in real time and stores a 2 year log I believe. The whole shebang is battery powered.

Hmm, does it read amps per leg, or just combined amps?
Does it read voltage and/or Hz?


Thanks

Aaron Z

 

[techman]

The inrush capability is based on three things:

1. As stated, the inertia of the motor-generator. This provides the energy to feed the inrush. You have the engine torque plus the j*omega^2 for the speed drop as the additional energy to provide the power for the inrush.

2. The "amount of copper" in the generator. Going light (or cheap) on the generator usually means wire in the windings just big enough for the load. At higher (in rush) loads, the additional current will result in a greater I^R voltage drop, and thus the voltage drop under that additional load will be higher. So bigger wire in the windings means less voltage drop, but higher cost.

3. The "iron" in the generator. This refers to the amount of steel in the laminations in the generator. More "iron" means that you can support a stronger magnetic field and therefore deliver more current. Again, cheaper generators tend to have just enough iron to meet the output requirement. This makes it lighter and lower cost. You see this with generators that have very little difference between the full load and surge capacities. The smaller the difference, the less iron in the design. For the technical types, as the current increases, so does the strength of the magnetic field in the gen. At some point the iron can not be magnetized further and the magnetic flux in the iron saturates, which means you can not increase it any further. This occurs around 20,000 Gauss in "magnetic" grade steels. The saturation value will define the limit of current that can be delivered. This is a law of physics, and when you hit that limit, that's it !

I always tell people to oversize generator heads, so a 12 KW head on a 10 KW rated genset will buy you much more surge capacity. On a residential generator, but the highest surge to running ratio that you can find. If will cost you more, but it likely has reserve in the copper wire size and additional iron in the laminations to provide more reserve capacity.

paul

 

[Rob-D]

For less than $10 at Harbor Freight you can get one that does the same: Digital Clamp-On Multimeter (note that you can only go over one leg of the wire going to the pump. If you go over both legs it doesn't read anything).

Aaron Z

That's a hard price to beat for a clamp on meter, even if you get just to kick around!

 

[aczlan]

That's a hard price to beat for a clamp on meter, even if you get just to kick around!

That was my thought in buying it... I have a nicer Ideal meter (which has a temp probe), but I cant even get a add-on amp-clamp for that price...

Aaron Z

 

[PineRidge]

Hmm, does it read amps per leg, or just combined amps?
Does it read voltage and/or Hz?


Thanks

Aaron Z

I don't know of any clamp on devices that measure voltage and/or Hz

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