[Milsurplus] Even Worse

[J. Forster]

> All the dynamics of all the control systems across the grid can make for
> an "interesting" day if something goes wrong.

The general philosophy seems to be "don't rock the boat". In Fitzgerald's
grad school electrical machinery course, we went on a tour of the MIT
Bitter National Magnet Lab, which has giant AC motors hooked to DC
generators for powering the experiments. These things were easily 15 feet
in diameter with buss bars like I beams.

Anyway, when they put the machines on-line, they would gradually bring
them up to operating speed with smaller motors and look at the phase
difference with a thing like a differential synchro hooked to a dial. The
pointer would turn CW or CCW, depending on whether the machine was above
or below sync speed. When the pointer was stationary, the machine was
operating at the right speed. Then they would goose it a bit up or down to
bring the phase difference to zero, and then adjust the field to match
voltages.

The final step was to connect the thing to the grid with a giant circuit
breaker.

The objective was to be as seamless as possible. A screwup and the city
would go dark.

Best,

-John

================



>
> Generally, most plants are looking to have a 1.0 PF at their point of
> connection to the grid even if it takes significant reactive to get there.
>
> (Yes, I know, gross oversimplification).
>
>
>
> J. Forster wrote:
>> By raising or lowering the field current, you can make the reactive
>> power
>> look capacitive or inductive respectively, but not instantaneously. The
>> L/R time constant of the field circuit is nowhere near zero. The L is
>> huge.
>>
>> -John
>>
>> ===============