Generac 15KW generator engine tear down

[tcartwri]

Hmmm.....

 

[FairfaxStu]

In a nutshell, it improves the power factor of inductive loads (motors), to .95. So it should be able to make any non EnergyStar rated appliance operate more efficiently. I got a 350w motor that runs 24/7 (primary circulation pump for my salt water tanks), not to mention a butt load of other motors, all in non EnergyStar rated appliances that are more than 3 years old, so I might just have to give this device a try. At $300, it would pay for itself in 5 month it it saved me 15% a month.

It's basically a big capacitor that install by your breaker panel via a 20A breaker, much like how a whole house surge protector would (which this unit also provides).

I am still extremely skeptical. As an EE, I can tell you that power factor is important especially for power companies so they typically put in massive capacitor banks in attempt to get the power factor as close to 1.0 as possible. This means that the power they generate which is measured in KVA equals what they sell which is measured in KW. Since they bill you at the KW level, not KVA, I don't entirely understand how this product would save you money.

That being said, for the price, it is probably worth trying. However, with the amount of power you pull, you may want to consider upgrading to one of the larger commercial units. One benefit you would see is that when the generator is running, you would get more power out of it for what you pay in propane.

 

[techman]

I am still extremely skeptical. As an EE, I can tell you that power factor is important especially for power companies so they typically put in massive capacitor banks in attempt to get the power factor as close to 1.0 as possible. This means that the power they generate which is measured in KVA equals what they sell which is measured in KW. Since they bill you at the KW level, not KVA, I don't entirely understand how this product would save you money.

That being said, for the price, it is probably worth trying. However, with the amount of power you pull, you may want to consider upgrading to one of the larger commercial units. One benefit you would see is that when the generator is running, you would get more power out of it for what you pay in propane.

I to am an EE with 35 years experience in industrial and power. It is true that correcting power factor in a residential setting WILL save money. Most likely up to one dollar per year. This is due to the fact that high reactance (KVA) will result in higher current for the power used (KW). This means that the current is higher and some additional heating losses (I^2R) will occur in wiring. That said, it will only take a hundred or more years to recoup your investment.

On a genset, improving power factor may help, since poor power factor (inductive loads) may push up the current beyond what is needed, and the generator does not have a large reserve for excess current in the form of heavier wiring and excess iron in the stator. You may effectively get less than rated capacity out of the genny if your power factor is poor and you are running it near the full rating. So power factor caps on the generator may be of some small help.

paul

 

[FairfaxStu]

I to am an EE with 35 years experience in industrial and power. It is true that correcting power factor in a residential setting WILL save money. Most likely up to one dollar per year. This is due to the fact that high reactance (KVA) will result in higher current for the power used (KW). This means that the current is higher and some additional heating losses (I^2R) will occur in wiring. That said, it will only take a hundred or more years to recoup your investment.

On a genset, improving power factor may help, since poor power factor (inductive loads) may push up the current beyond what is needed, and the generator does not have a large reserve for excess current in the form of heavier wiring and excess iron in the stator. You may effectively get less than rated capacity out of the genny if your power factor is poor and you are running it near the full rating. So power factor caps on the generator may be of some small help.

paul

Thanks, Paul. That is exactly what I was thinking. Perhaps in some areas of the country they sell power by KVA but not here in Virginia. I can see getting a minor benefit out of it, but mostly when having the genset running.

-Stu

 

[pclausen]

Makes sense. If such a device was truly able to get you a 15-20% savings, everybody would have one already.

Would the caps aid with the start up current draw of large loads? I think this 15kw gen-set will be border line as far as being able to start the compressor in my 5 ton A/C unit.

 

[techman]

Makes sense. If such a device was truly able to get you a 15-20% savings, everybody would have one already.

Would the caps aid with the start up current draw of large loads? I think this 15kw gen-set will be border line as far as being able to start the compressor in my 5 ton A/C unit.

No benefit for startup

paul

 

[FairfaxStu]

I think this 15kw gen-set will be border line as far as being able to start the compressor in my 5 ton A/C unit.

You are probably right. I was thinking maybe you could setup the transfer switch to turn on the AC load before everything else. Then I thought more about it and realized that the AC will be cycling on and off anyway. Do you have a clamp meter that you could measure the current draw of the AC with? I am guessing it is about 40-50 amps. With that information we can probably help you to determine if you will have an issue or not. You may also want to take readings of the other circuits you need to support with the genset.

 

[techman]

Most modern ACs and even most digital thermostats will delay the AC startup after a power outage. I know my systems wait about 10-15 minutes and the time is psuedorandom, so my three units will never start at the same exact time. Now my zones are only one 2 ton and two 1.5 ton units. They are easier to start than a larger unit. When I start my 10KW genset (diesel) I just let the ACs come on on their own. No problem starting the 3rd system with the other two running. The only thing I switch off is the hot water heater, and the stove/oven if it was on at the time of the outage.

paul

 

[aczlan]

Makes sense. If such a device was truly able to get you a 15-20% savings, everybody would have one already.
Would the caps aid with the start up current draw of large loads? I think this 15kw gen-set will be border line as far as being able to start the compressor in my 5 ton A/C unit.

Might get the "hard start kit" for your compressor. That has a cap which makes it pull less power on startup.

Aaron Z

 

[techman]

Might get the "hard start kit" for your compressor. That has a cap which makes it pull less power on startup.

Aaron Z

Actually a hard start kit will increase the initial inrush. It allows for a greater starting torque. Without a hard start kit, the compressor will start more slowly, allowing a longer time at high inrush current. The quicker current spike may assist with getting it started faster and possibly help with the genset.

paul