Power Outage

[gar]

121031-0930 EDT

My neighborhood has a 3 phase delta supply.

The night before last my neighbor's, different transformer and phase, lost power about midnight. I did not loose power, and I do not know what my voltage was. My voltage could have been low, meaning 90 to 100 V.

Just after 7 AM yesterday my lights flickered some. Then out my back window I noticed arcing near the ground along the pole line and about 1 to 2 houses away in a tree-ed area. Some while later the fire department came and put up yellow tape.

I looked at my voltage and it was jumping around, and therefore I decided about 9 AM to set up my generator. It is a Honda 5000 W.

Went next door to the new neighbors, different than the above mentioned neighbor, and turned off their main breaker. They have a very large side-by-side freezer-refrigerator. I told them I could power the refrigerator. Ran an extension cord to them. Checked the power input and it was almost 900 W. Quite large. Voltage was 110 V at their end of my 120 foot extension cord. About 118 V at the generator. For comparison my large freezers are about 300 W initially and drop to about 180 W.

When I first powered my generator I could not connect the house load because the generator stalled. This results from 4 motors all wanting to start at the same time, plus other loads.

Remove loads, got generator running, then gradually added loads. Normal daytime house load is 2 to 3 kW. Once the system is up and running there is no problem because the likelihood of more than one motor starting at the same time is near zero.

I should have used less than than 30 kWh on the generator yesterday and fuel consumption was about about 6 gallons of gasoline. Gasoline is worth about 33 kWh per gallon. Thus, overall efficiency was less than 16%. An important question is how to greatly increase this efficiency?

Because the generator is too noisy to run all night it was shut down about 11:30 PM. In preparation for this I bought 14 # of dry ice. Normal internal freezer temperature is about 0 F. 5# of dry ice was put in each large freezer at about 8 PM. Washtenaw Dairy closed at 9 PM so I could not wait until later to get the dry ice. 4 # was put in the freezer part of the refrigerator-freezer. My neighbor had no idea how much dry ice to use for her freezer and she bought #15. By 11:30 PM most of my 5# block was gone. So her 15 # was a better estimate of a needed value for overnight.

My big freezer temperature was up to 20 F at 7:00 AM today. In the ref-freezer combination the freezer temperature was up to 27 F.

Outside temperature was about 40 F overnight. House temperature was 70 F at 11:30 PM and 65 F at 7 AM. Wind was not too great last night. Under these conditions the thermal time constant of the house is about:
(70-65)/(0.63*30) = 0.26 for the portion of one time constant.
The time for this change is 7.5 hours.
Thus, approximate thermal time constant is 7.5/0.26 = 28.8 hours.

The electrical problem is one lost phase on the primary distribution lines.

The downed wire and arcing were located beyond my transformer. So until DTE opened the phase, probably at the substation, I still had power but some flickering. I had no usable power after my phase was opened somewhere between the substation and before my transformer. I have monitored my source voltage at various times thru the last day and it has varied from 20 V to 104 V based on 120 V. Thus, many neighbors have loads that are cycling on and off (thermal overloads kicking off) that have not opened their main breaker. This is much like the problem of an open neutral. Houses that share the open phase provide a split load across the one functional phase. As the load impedances change on each side of the open phase it changes the voltage distribution.

Dry ice is about $1.25 per pound in small quantities. 15 # is probably a reasonable minimum for a large freezer for 8 to 10 hours. The generator approach is less expensive than the dry ice approach.

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[kwired]

Is there wide spread outage problems in your area? Otherwise why is it taking so long to have the problem fixed?

 

[K8MHZ]

Is there wide spread outage problems in your area? Otherwise why is it taking so long to have the problem fixed?

I think both Consumers Energy and DTE have sent most of their linesmen to the NYC/Jersey area. They (Consumers) took 48 hours to get to a call that usually gets a visit in less than one.

 

[K8MHZ]

Gar,

You seem to have an inordinate amount of outages in your area. Have you thought about keeping a log?

 

[gar]

121031-1023 EDT

kwired:

The service response time is not good, but I do not know if I can expect better. Yesterday there were a total of 120,000 customers without service. Last night and today maybe 50,000. But, nothing like the troubles on the east coast. Some of the normal contract linemen from here have been sent east to help there, and thus manpower is short here. We are a small pocket, about 50 customer, and they will obviously try to get big blocks first.

This points out the need for more electric customers to have backup capability. But in our general area there are not a lot of electric customers with generators. A neighbor back of us just takes the attitude they will go to a motel. They could easily afford a generator, she is a pediatric heart surgeon. What do you do when there is a more severe problem? Like the great eastern blackout. One should be prepared.

For the most part all our normal living needs can be met with the 5000 W Honda. You just don't try to start the generator with the whole house load on. A more efficient engine is needed to reduce running costs. Probably dual fuel, gasoline and natural gas, should be available.

I can see the value of a larger generator combined with two engines and a large flywheel. One engine would be for normal load. In my case 2 to 3 kW. The second engine would be used singly or in combination with the first engine for higher demand times. The fly wheel would be used to handle all the motor starting or other high inrush current loads. With this arrangement one could raise the overall efficiency of the system.

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[mike_kilroy]

121031-0930 EDT
I should have used less than than 30 kWh on the generator yesterday and fuel consumption was about about 6 gallons of gasoline. Gasoline is worth about 33 kWh per gallon. Thus, overall efficiency was less than 16%. An important question is how to greatly increase this efficiency?

Isn't the ICE (internal combustion engine) said to be about 16% efficient? So did you just prove it with your numbers, assuming the electric generator itself is about 90% efficient?

My electric car has 35kwh of battery and can go about 100 miles on a charge so I figure it as around 100mpg. This seems to jive with ICE equiv that goes 20-25mpg on same 30kwh/1gal-gas? Since car companies can push this upto about double those numbers, seems if you do similar to your generator you could cut fuel in half? But would the cost be worth it? I wonder.

 

[ATSman]

Sandy

Sandy

I have heard that the storm Sandy is unprecedented and the effects will be long lasting.
It would be interesting to hear from members all along the East coast about how it is affecting them first hand.

 

[gar]

121031-1104 EDT

K8MHZ:

I feel that way also. The PSC is trying to keep rates down, and there is a lot less good tree trimming being done. Service is nothing like it was 50 years ago. In fact in the 30s, depression time, if a street light was out it was fixed in about 1 hour. Today your lucky if it gets done in 7 days.

I should note that in the last 6 years my cost has gone from about $0.12 to $0.16 per kWh. This includes various fee increases concocted by government. I expect it is fairly quickly going to increase more. Coal is effectively being banned.

If the power company electricity cost goes up enough, and we can increase the engine generator efficiency, then with natural gas it might be possible to generate electricity and with the waste heat do water and house heating at a lower cost than buying electricity from a central plant.

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[gar]

121031-1123 EDT

Modern auto engines are probably in the 30 to 35 % conversion efficiency range at their optimum point.

A person I recently talked with has an engine design that might hit 45% with natural gas in the couple hundred horsepower range. Not quite as efficient at lower power levels. So a 10 to 20 HP motor would not be as good. But if that waste heat can be put to good use, then an overall system could be viable.

Note: heat can be used for cooling. The entire Ford engineering lab, built in 1925, was cooled with steam.

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[K8MHZ]

121031-1023 EDT

kwired:

The service response time is not good, but I do not know if I can expect better. Yesterday there were a total of 120,000 customers without service. Last night and today maybe 50,000. But, nothing like the troubles on the east coast. Some of the normal contract linemen from here have been sent east to help there, and thus manpower is short here. We are a small pocket, about 50 customer, and they will obviously try to get big blocks first.

This points out the need for more electric customers to have backup capability. But in our general area there are not a lot of electric customers with generators. A neighbor back of us just takes the attitude they will go to a motel. They could easily afford a generator, she is a pediatric heart surgeon. What do you do when there is a more severe problem? Like the great eastern blackout. One should be prepared.

For the most part all our normal living needs can be met with the 5000 W Honda. You just don't try to start the generator with the whole house load on. A more efficient engine is needed to reduce running costs. Probably dual fuel, gasoline and natural gas, should be available.

I can see the value of a larger generator combined with two engines and a large flywheel. One engine would be for normal load. In my case 2 to 3 kW. The second engine would be used singly or in combination with the first engine for higher demand times. The fly wheel would be used to handle all the motor starting or other high inrush current loads. With this arrangement one could raise the overall efficiency of the system.

.

.

Is your generator an inverter type? The kind that doesn't have to stay running at 3600 rpm to maintain 60 Hz?

If not, you are not using an efficient generator. The ability to idle with no load makes a huge difference.

There are flywheel storage systems now. My take is that if they were 'all that', we would see them everywhere.

LED lighting for power outages has made a big difference. Making your living space efficient is way cheaper than coming up with an energy storage contraption.

I can't remember our gas service ever failing. Using NG for outages is prudent. I have a NG space heater that heats the entire house and requires no electricity. All I really need electricity for is H20 pump and I think next year there will be a pitcher pump in line with the elec. pump.

It's best to not depend on one energy source. You should have at least two means, even if only propane powered camping type appliances, of energy for heat, lights, cooking and water. City water may be hard to back up, but I have found that it never fails anyway.

 

[gar]

121031-1138 EDT

K8MHZ:

No I do not have an efficient generator. Further it is noisy. I bought it in response to the great eastern blackout. I took what I could get, no analysis.

The point of a good flywheel is to handle the fractional second to maybe 2 second time period for starting motors without requiring a larger engine. The generator itself can handle large short time overloads, an internal combustion engine can not.

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[gar]

121031-1147

mike__kilroy:

One difference between your electric car and a typical ICE car is that the electric car has some regenerative braking, the normal car does not.

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[K8MHZ]

121031-1138 EDT

K8MHZ:

No I do not have an efficient generator. Further it is noisy. I bought it in response to the great eastern blackout. I took what I could get, no analysis.

The point of a good flywheel is to handle the fractional second to maybe 2 second time period for starting motors without requiring a larger engine. The generator itself can handle large short time overloads, an internal combustion engine can not.

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You need to take a look at the new inverter generators. You will be amazed at how quiet and efficient they are. As for the flywheels, just what problem are you trying to solve? Is it in response to your generator stalling when trying to start several motors?

I would suspect a problem with the engine. The breakers on the generator should trip way before the generator is loaded to the point of stalling the engine. That being said, if the engine didn't stall, the breakers probably would have tripped and so much for any help from the hypothetical flywheel.

On Edit: Oh, and I can't figure out how a motor that would stall trying to run a loaded generator would also not stall trying to turn a flywheel big enough to not stall trying to run a loaded generator. IOW, if the motor is big enough to spin the flywheel, it should be big enough to turn the generator. No?

 

[K8MHZ]

And....

Would the motor(s) not have to be large enough to run both the load and the flywheel at the same time?

To me the added energy required to keep a large flywheel spinning is a waste.

Also, remember that once the flywheel drops below the rpm needed for 60 Hz, it's useless no matter how much energy is still stored in it and just becomes another load.

 

[gar]

121031-1656 EDT

K8MHZ:

DTE has arrived to fix the line. They just disconnected my transformer so now I have essentially 0 V as expected and measured.

On flywheels. To rotate a flywheel at constant speed requires no energy except for windage and bearing friction, and windage is really friction. A rotating flywheel is an energy storage device.

In my opinion 1800 RPM is a better speed than 3600. Less noise and dynamic balance problems.

Would the motor(s) not have to be large enough to run both the load and the flywheel at the same time?

No. The engine has to be large enough to supply the average power of the load for times longer than represented by the peak capability of the flywheel. The flywheel supplies the peak power, and that has to be replenished by the engine, but not instantaneously.

No power generator ever operates at precisely 1800 RPM.

E = M*V²/2

The change in stored energy for a 1 % speed change is M*(V²- V²*0.99²) = M*V²*(1-.098) or a 2% change in energy for a 1% change in speed.

The peak inrush energy requirements will determine the mass of the flywheel. The flywheel mass won't be huge for home applications. Might be need for a slip clutch to get the flywheel accelerated to speed.

Electric machines, such as many motors and generators, can be heavily overload for a short time. This is what Charles Kettering understood and that allowed him to create an electric cash register at NCR. Later the same concept was applied to the automotive electric starter.

http://www.sinclair.edu/academics/lcs/departments/his/OhioHistory/StudentProjects/CharlesKettering/
http://en.wikipedia.org/wiki/Charles_F._Kettering

Gasoline engines have a peak power rating and this can also be near the continuous duty rating. Contrast that with an electric motor, in particular a DC shunt wound type, that can supply a large amount of power (overloaded) for a short time, but can not run close to this level continuously. Thus, a flywheel can supply energy to a generator for short times to handle inrush loads without the gas engine being designed for those peak loads.

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[mivey]

On flywheels. To rotate a flywheel at constant speed requires no energy except for windage and bearing friction, and windage is really friction. A rotating flywheel is an energy storage device.

I nominate you to install one of the vacuum-encased high-RPM composite flywheels.

In my opinion 1800 RPM is a better speed than 3600. Less noise and dynamic balance problems.

Are you thinking just bolt one on the generator? What would you do with the energy during a fault or if the load trips out? The generator can only dissipate so much energy. Why not a paralleled system that can spin at higher speeds and thus require less mass?

Might be need for a slip clutch to get the flywheel accelerated to speed.

and to take it off line during faults or loss of load.

Sounds like a fun experiment.

 

[gar]

121031-2028 EDT

mivey:

Good suggestions. Important to think about.

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[gar]

121101-0801 EDT

Update.

My power is back on. DTE has restored power to 107,000 customers leaving 13,000 still without power.

According to the DTE lineman we have one neighbor on our block that is using 3 phase power. Probably for an air conditioner. Also there is a switch point for our line about 1/3 of the distance from my home to the sub-station.

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[kwired]

As far as engine not being able to power a generator with a surge of current, most engines are sized for optimal performance at the full load rating of the generator, I would guess.

A few years ago after an ice storm caused widespread distribution problems around here, I had a farmer that had a tractor PTO driven generator for standby power for his farm (PTO driven generators are pretty common on farms).

He needed to pull some corn from a silo for feeding livestock, but the silo was on a separate service from the main farm and there was no transfer equipment. Generator had a receptacle, and he decided to connect a cord directly to the motor to power it. He ended up miswiring in the motor connection box and somehow created a line to line short circuit. When that short circuit load hit the generator it snapped the universal joint on the PTO drive shaft.

Had he been driving this generator with a 20-30 HP tractor, maybe it would have stalled the tractor, but he was using a tractor with output of at least 100 HP. Generator was probably in the 20-25 KVA range.

 

[gar]

121101-1057 EDT

kwired:

Full load rating of a generator (alternator) is a thermally determined value. This rating is for a continuous load that will not cause the maximum hot spot temperature in the generator to exceed some absolute value, like 120 C, while the generator ambient is at some defined value. If the generator is some higher ambient, then the power rating has to be derated.

The generator maximum power capability will likely be much greater than the thermal rating. External control circuitry could make the two power values the same. There might be some generator designs that could cause limitation of peak power capability.

As a very rough estimate maximum power output to the load occurs when the load impedance equals the source impedance. In a DC system it is fairly easy to see and measure the characteristics. For high efficiency a generator is designed with a low source impedance compared to the load impedance. Thus, peak power capability for a generator will be much greater than its continuous rating.

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