There is a gas shortage here on Longisland and after waiting one hour on line there was only 87 octane and i had to use it.Should i get a bottle of octane boost or will i be ok?
thanks

 

Did what you had to do. Hope things get better, for you, back there real soon.

 

You'll probably be okay, but if you can get octane booster, why not?

 

dont worry about it, a couple tanks of 87 will not hurt a thing.

 

I always use premium in mine, but my niece also has a 2001 and she never runs premium. Only 87 octane. She's at 140k and the only problem she has had was to replace the head gaskets at 130k.

 

Thankyou all for the reply!!So far i dont hear any pinging so i think im ok for now.A disco is the last thing you want to own during a gas shortage.

 

No way, a DII is great, so much room for extra gas!

 

Octane boost actually reduces the octane rating not increase it.

 

I ran 87 in 04' for many years as the dealer told us when I bought the truck new that it didn't need Higher octane. Never had any pinging. When I tore the engine apart last year for low oil pressure the pistons were in great shape. You'll be find, sounds like you got bigger fish to fry. Good Luck.

 

don't ask a lot of it - don't move briskly on the gasoline and you'll be ok.

Why are Rockaway beach people still in the dark?

An 11,500 volt e diesel generator could be hooked to the overhead wire and power a whole street - providing the overhead cutoff to the rest of the system has been utilized


Let's begin at the beginning. A synchronous electrical machine (generator or motor) is intended to be operated at a constant speed (synchronous speed). When the generator rotor is rotated, the magnetic flux of the generator rotor induces a voltage in the generator stator windings--called the generator terminal voltage.

When the speed of the generator rotor is constant (or at rated) and the excitation is constant, the generator terminal voltage will be constant, or stable. The magnitude of the generator terminal voltage is a function of the strength of the magnetic field of the generator rotor--since the generator rotor is being rotated at a constant speed: synchronous speed.

The exciter controls the strength of the rotor magnetic field, and the strength of the rotor magnetic field controls the magnitude of the generator terminal voltage. (Again, we are presuming the generator rotor is spinning at synchronous speed, which is also the rated speed for the generator, for the purposes of our discussion.)

For all intents and purposes, the generator terminal voltage is usually held relatively constant during normal operation. In fact, most synchronous electrical generators are rated for a particular voltage, (for example, 11,500 Volts, or 11.5kV, or 13,800 Volts, or 13.8 KV), plus-or-minus 5%, meaning that the generator terminal voltage is only to be operated within +/-5% of 11.5kV or +/-13.8kV.

That's a fairly small range, +/- 5%. And, again, it's kind of the intent to operate most electrical machines (any kind of electrical machine) at, or very close to, a particular voltage anyway. So, we're going to say that, in general, the generator terminal voltage remains relatively constant--that is, it is relatively unchanging.

Again, to have a constant terminal voltage, the generator rotor magnetic field must be held constant. And the exciter controls the strength of the generator rotor magnetic field. So, that means the exciter will normally operate at a relatively constant, stable, output to maintain a relatively constant, stable generator terminal voltage.

Now, when a synchronous generator and the prime mover (a GE-design heavy duty gas turbine in your case) is synchronized to a grid in parallel with other generators and the primer movers driving those generators, current can flow in the generator's stator windings. To make more current flow "out" of the stator windings one increases the torque produced by the prime mover. In your case, that means increasing the fuel flow-rate to the turbine. The generator converts the torque to stator amperes.

The equation for electrical power for a three-phase machine is:

Power (Watts) = Volts * Amperes * (3^0.5) * (Power Factor)

For the time being, we are going to consider the Power Factor of our generator in this example to be 1.0 and stable; constant; unchanging.

So, lets' define an operating condition: we are holding the generator terminal voltage constant (by holding the generator rotor excitation constant), and we are presuming the power factor to be 1.0, and unchanging. The square root of three is a constant (it can't/doesn't change; it's always 1.7320).

So, to increase power, the only component of the power equation that can be changed is the generator stator amperes. And, since a generator is a device for converting torque into amperes, if we increase the torque being applied to the generator rotor, the amperes flowing in the generator stator will increase. And, when the generator stator amperes increase, then the power being produced by the synchronous generator will increase.

So, fuel equals torque, and torque equals amperes, and varying amperes varies the power produced by the generator. So, to make more power, increase the fuel flow-rate. To make less power, decrease the fuel flow-rate.

Oh, if it were ONLY that simple, though. As the amperes flowing in the generator stator increase as the fuel flow-rate to the turbine increases, one of the effects is that the magnetic field associated with the generator stator increases. (Remember: current (amperes) flowing in a conductor produces a magnetic field.)

As the field associated with the generator stator increases, it "reacts" with the field of the generator rotor. Some people like to describe the resultant interaction of the generator stator's increasing magnetic field strength as decreasing, or weakening, the generator rotor field strength. (At least that's how I was taught, and how I like to describe it; and I'm doing the describing here. There are some people who like to use vectors and maths to describe it in other ways, but, in essence what we have is an interaction between two magnetic fields in the same space, and something has to "give" when one increases. No matter how you "describe" it.)

Now, when the generator field strength decreases that causes the generator terminal voltage to decrease. Oh--but we said we want to maintain the generator terminal voltage relatively constant. What to do??? Increase the excitation, to increase the generator rotor field strength to maintain the generator terminal voltage.

The exciter, when it's being operated in what's called "Automatic" or "AC" mode, is monitoring the generator terminal voltage, and it adjusts the excitation as required to try to maintain the generator terminal voltage setpoint set by the machine's operator. If the terminal voltage goes down, the exciter will increase the excitation to try to maintain the generator terminal; the opposite happens if the generator terminal voltage increases.

So, as a synchronous generator is loaded (by increasing the fuel flow-rate to a gas turbine being used as a prime mover to provide torque to the generator rotor) if no action is taken by the operator or the exciter control system then generator terminal voltage will decrease below rated or desired. That's why it's required to increase excitation as the generator is loaded to maintain something near rated generator terminal voltage.

Conversely, when a synchronous generator is being unloaded (be decreasing the amount of fuel flowing to the gas turbine), if no action is taken to reduce the excitation the generator terminal voltage will increase above rated or desired.

All of that is basically true for a stable or unchanging power factor, and we assumed it was 1.0. Now, lets' presume that your generator is operating at 50% of rated power output, stably, and that the power factor of your generator is 1.0 (which, coincidentally means that the excitation being provided to the generator rotor by the exciter is exactly equal to the amount required to make the generator terminal voltage equal to the grid voltage with which the generator is synchronized). If the operator then increases the excitation being applied to the generator rotor the Power Factor meter will drop below 1.0 in the Lagging direction. And the VAr meter will increase from 0.0 in the Lagging direction.

Note that I did NOT say the operator had done anything to change the load (watts/KW/MW) of the generator by changing the fuel flow-rate to the gas turbine driving the generator--he only changed the generator excitation. And, I'm going to take the specifics one step further--by saying that the unit is NOT being operated with Pre-Selected Load Control enabled and active. The unit had been manually loaded to approximately 50% of rated load without placing the Speedtronic in any kind of automatic load control.

Essentially what the operator had done was to attempt to increase the grid voltage by increasing the generator terminal voltage (sometimes called "boosting"), and while the generator terminal voltage and the local grid voltage may have, in fact, increased slightly what really happened is that reactive current began to flow in the generator stator windings.

From a generator's perspective the reactive current is considered to be inductive and is called lagging reactive current, or lagging VArs. If the operator continues to increase the excitation being applied to the generator rotor, the Power Factor meter will continue to decrease below 1.0, and the VAr meter will continue to increase above 0.0 in the Lagging direction.

What's happening when the operator is increasing the excitation being applied to the generator is that the total amount of energy that's being input to the generator is being split between real power (watts/KW/MW) and reactive "power", and that the percentage of real power being produced is decreasing. Power Factor is a measure of the amount of real power being produced versus the total amount of power being applied to the machine.

So, the reactive current flowing in the generator stator windings is controlled by controlling the excitation being applied to the generator rotor. And the "real" power flowing in the generator stator windings is controlled by the amount of torque being applied to the generator rotor. It's really that simple

Now, lets' say the unit is operating at a stable power output and with a Power Factor of 1.0 (which means 0.0 VArs). After a while the operator looks up to see the Power Factor meter has changed! It has decreased below 1.0. And, the VAr meter has increased above 0.0. Both meters are indicating in the Leading direction.

This means that grid system voltage has increased above the level it was previously operating at, which means the excitation being provided to the generator is now not sufficient to keep the generator terminal voltage equal to the grid voltage. This means that reactive current is now flowing in the generator stator windings.

The operator was told to maintain a Power Factor of 1.0, and a VAr reading of 0.0 VArs. What does the operator do to return the Power Factor meter to 1.0 and the VAr meter to 0.0?

He increases the excitation. He doesn't increase the fuel flow-rate; he increases the excitation.

Fuel is watts, or KW, or MW. Fuel is REAL power.

Excitation is VArs. Excitation is REACTIVE power.

Finally, you brought up the subject of speed. A synchronous generator is supposed to be operated at a constant speed, called synchronous speed. For a two-pole generator operating on a 50 Hz system, that synchronous speed is 3000 RPM.

That's because the speed of an AC machine is directly proportional to the frequency of the AC mains (the grid) with which it is connected. The formula is:

F = (P * N) / 120,

where F = Frequency, Hz,
P = Number of poles of the generator rotor,
N = RPM

When synchronous generators are operated in parallel with each other--when they are SYNCHRONIZED with each other--they are all operating at the same frequency under normal conditions. And because, nominally, optimally, allegedly, the system frequency is constant (or relatively constant; meaning it changes relatively little and is relatively stable) all synchronous generators, and the prime movers directly connected to the synchronous generators, are all rotating at constant speeds that are directly proportional to the frequency of the grid with which they are connected.

In reality, grid frequency in never exactly 50.00 Hz, and as grid frequency varies so do the speeds of the generators and the prime movers directly connected to those generators. But, for all intents and purposes--in most parts of the world--the frequency is relatively stable and even though the frequency varies by hundredths or tenths of a Hz, the machine speeds vary by an almost imperceptible amount that is directly proportional to the frequency variation.

And, when the grid frequency disturbances are large, then generator and prime mover speed variations are large.

That's because all of these machines are locked into synchronism with each other. And, allegedly, supposedly, somewhere there is a grid regulator that is monitoring the load on the grid and ensuring that the amount of generation on the grid exactly matches the amount of load--which is what's required to make the system frequency exactly equal to nominal (in your case, 50, or 50.0, Hz).

When the amount of load exceeds the amount of generation, then the frequency will begin to decrease. When the amount of generation exceeds the amount of load the frequency will begin to increase.

But, in any case, unless your prime mover is VERY large with respect to all of the other generators on the grid with which it is synchronized, increasing the fuel flowing to the gas turbine will not appreciably increase the speed of the turbine, and hence will not appreciably increase the speed of the generator rotor, and hence will not appreciably increase the frequency of the output of the generator. The speed of the generator rotor, and of the Frame 9FA GE-design heavy duty gas turbine which is directly coupled (connected) to the generator rotor, is controlled by the frequency of the grid with which it is SYNCHRONIZED.

I keep emphasizing the work synchronized because it's important to understand that there are very great magnetic forces at work in synchronous machines that keep the speed directly proportional to frequency. Even though you increase the fuel flow-rate to the turbine when the generator is synchronized to the grid, the speed of the turbine--and the generator rotor--does NOT increase. The increased torque developed by the increased fuel flow-rate is converted by the generator into increase stator amps, which takes us back to the first formula in this response.




Not sure if the power com