• Pantograph, phase gap, etc.

  • General discussion about locomotives, rolling stock, and equipment
General discussion about locomotives, rolling stock, and equipment

Moderator: John_Perkowski

  by timz
Another good explanation from Sirsonic. Maybe when DRN said no magnets he meant no magnets at the gaps where voltage/freq doesn't change? Strictly speaking, does the term "phase gap" imply a change of phase only? If so, what are we supposed to call a voltage-change gap?

  by glennk419
pgengler wrote:While we're being inquisitive on this, is there some sort of posted sign/other notification that a phase gap is coming up, or is it something the engineer just knows (from having been qualified on the territory)?
On Septa, there is a phase gap just north of the tunnel portal at Girard Avenue which is the division between ex-RDG and ex-PRR (now Amtrak) power. This PG is "protected" by signals over each of the four tracks which look like PRR position lights except there are eight lights in a full circle and no center aspect. The signals are located several hundred feet on either side of the gap. Usually the only noticeable effect of passing through the gap is that the ventilation shuts down for a few seconds although I have seen the emergency lighting come on occasionally and once in a while, you'll get a little buck out of the older Budds.
  by tedklugman
wow, thanks for the very informative replies. So this means that there is no traction power available? What happens if the train stops in the gap?

  by PRRTechFan
Wow, Sirsonic; great post, great information! Thank you for filling in all the gaps; no pun intended!

You mentioned the green catenary poles as a reminder to E60 engineers to manually trip the MCB at the gap. I had not heard that story before, but I do remember they had a terrible time at first with them blowing fuses. Everybody was desperately looking for Bussmann KAB-200 fuses. NJT must have called every electrical distributor in the state for them. They were "semiconductor fuses" specially designed to protect the power devices (SCR's and such) in high power controls. I thought at the time that there might be a connection between blowing fuses and the phase gaps.
timz wrote: Strictly speaking, does the term "phase gap" imply a change of phase only? If so, what are we supposed to call a voltage-change gap?
The term phase gap or phase break applies wherever there is an electrical "discontinuity" in the catenary system. When high voltage AC traction was in its' infancy, there was only one voltage and frequency: 11kV and 25Hz. Larger systems had more than one generating source, and although the different sources were usually kept in synchronism, they were not as "tightly" interconnected back then as our utilities are today... (Forgetting the summer 2003 northeast blackout brought to you by our friends at First Energy, of course...)

If the different generating stations serving the railroad lost sync but remained connected to opposite ends of the same catenary, damaging circulating currents back and forth would cause even greater instability possibly leading to both plants being tripped off line. So the phase gap was created. If the power systems remained in sync, there was no voltage or phase difference across the gap. If the systems lost sync, the voltage and frequency would remain the same on each side, but the "phase" (or "timing") of the voltage between the two systems could differ, hence the term "phase gap".

Today, we not only can still have differences in phase (...as in using different utility companies on opposite sides; although they should be in sync...), but differences in voltage and/or frequency as well. They all represent an electrical "discontinuity" at the gap, so the terms "phase gap" or "phase break" to represent the point of an electrical discontinuity are still used.

  by BlockLine_4111
Hence why E60s could not run in push mode ?

  by Typewriters
From Penn Central CT 290, Electrical Operating Instructions, issued 1973, and from page 29:

Phase Break Signs and Indicators.

1. Phase break signs (insert here a pic of a rectangular sign with PB on its front) are located on first catenary pole in advance of a phase break.

2. Position light phase break indicators of type (insert here a pic of a light with 8 lenses, arranged in a circle) shown are located in advance of the phase break sign. When indicator is lighted, a section of the phase break is deenergized and all electric trains approaching a phase break on any track will be governed by the following:

One engine with one pantograph up: Place controller in OFF position before entering the phase break, keeping it in that position until after the phase break is passed.

One engine with both pantographs up, two or more engines, and multiple unit trains: Place controller in OFF position. Metroliner place controller in BRAKE RELEASE position, keeping it in that position until after the phase break is passed. Drop pantographs before entering the phase break, keeping them down until after the phase break is passed.

3. Phase breaks are located as specified in the timetable.

Thought you might find this of interest.

-Will Davis

  by BlockLine_4111
An excellent discussion. :wink: :wink: