Re: Phase breaks and phase balancing.
If I recall correctly, the 25 Hz power for the PRR was generated and transmitted as single phase. The phase breaks were therefor not required for balancing phases, but likely to prevent circulating currents due to minor phase and voltage variations. The transformer substations didn't allow for as fine a voltage control as was possible with the M-G sets on the Milwaukee, which often operated the electrified sections without any breaks (other than the Avery-Othello gap).
It would be possible to convert three phase AC to DC and then invert back to AC, but that messes with the economic rationale for commercial frequency electrifications (i.e the substations is just a transformer and circuit breaker. The frequency changer sets used by the PRR did a decent job of balancing the 3 phases on the commercial frequency side.
- Erik
erikem Re: Phase breaks and phase balancing. If I recall correctly, the 25 Hz power for the PRR was generated and transmitted as single phase. The phase breaks were therefor not required for balancing phases, but likely to prevent circulating currents due to minor phase and voltage variations. The transformer substations didn't allow for as fine a voltage control as was possible with the M-G sets on the Milwaukee, which often operated the electrified sections without any breaks (other than the Avery-Othello gap). - Erik
Correct: The power transmission lines you see today on the old PRR are paired +69Kv and -69KV. This is very similar to the power to your home 110V/220V ie 110 V to ground and 220V line to line. Phase breaks are needed to separate the + and - values after they are stepped down by a 5.75 to 1 ratio transformer to the nominal 12Kv that Amtrak operates its CAT.
Milwaukee electrification was DC so no phase breaks needed. Power useage from various substations would be divided depending on how close a motor was to each substation. Do not know the math.
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