24 Nov 00 21:52
1. Hurley J.D., Baldwin M.S. "High-Response Excitation Systems on Turbine-Generators: A Stability Assessment," IEEE Transactions on Power Apparatus and Systems, Vol. PAS-101, No. 11, pp. 4211-4217, November 1982
This reference describes the H constant, which is internal to the generator model described by stability constants including H; Exciter Block (IEEE Type 1, in Fig. 2), which includes Ta constant (0.02 sec); voltage regulator block; and downstream network (system) to be able to evaluate the complete agregate in Fig. 1. Also, a Power System Stabilizer (PSS) is studied therein. Therefore, it appears the the Ta utilized at the exciter regulator has a rather complex context with the constant H.
2. Knable A. H. "Electrical Power Systems Engineering," McGraw-Hill Book Co., 1967, page 133
This reference appears to present similar equation to the Jack Nov 24 posting where
df/dt=Pa x 30 / H
f .... frequency in Hz
t .... time in seconds
Pa ... accelerating power in per units (p.u.) (not torque!)
H .... energy loss in a rotating mass in p.u.-sec
There is no sign of Ta/sec (starting time constant of the complete aggregate).