On a visit to Lite-trol yesterday to get a D50 fixed, Steve Short shows me this:
6 - 50 amp Luxtrol auto-transformers in a vertical stack, plus a few sitting off to the side. Being repaired.
These belong to the Shubert Theater, NYC and are the dimmers for house lighting. Along with the multitude of AT dimmers are the associated "paralleling chokes" that combine the outputs of 2 50 amp dimmers into one 100 amp output (the choke accounts for slight variations in individual dimmer output voltage). With 6 dimmers in a stack, you get 3 - 3 phase/100 amp dimmers that feed the branch circuit breaker panels. There was a 2nd stack being repaired as well, that one was a motorized stack.
As Steve and I chat, I recall that the Shubert was the theater that A Chorus Line went into on it's Broadway run, and that I would venture that these AT dimmers replaced the existing DC dimmers when the theater converted to AC for ACL. That places the install possibly at 1975'ish.
Converting to AC meant that you either A) Go to autotransformers or B) Convert to 100 amp capable SCR dimmers and associated control system. Or C) Convert every branch circuit to a single 15 amp SCR circuit with associated control system.
Even now, 38 years later, 100 amp SCR dimmers, while "doable" are not always the best solution (for reasons I've never determined).
As well, I doubt that ANY electronic control system installed in '75
would still be in use, having developed it's own issues long ago and having been replaced possibly at least twice, if other systems are any track record.
The Shubert Organization has a warehouse in NYC that contains extra and stored away for future use, AT dimmers just for this eventuality, of the dimmers failing over time, in this case, 37 years later.
6 - 50 amp Luxtrol auto-transformers in a vertical stack, plus a few sitting off to the side. Being repaired.
These belong to the Shubert Theater, NYC and are the dimmers for house lighting. Along with the multitude of AT dimmers are the associated "paralleling chokes" that combine the outputs of 2 50 amp dimmers into one 100 amp output (the choke accounts for slight variations in individual dimmer output voltage). With 6 dimmers in a stack, you get 3 - 3 phase/100 amp dimmers that feed the branch circuit breaker panels. There was a 2nd stack being repaired as well, that one was a motorized stack.
As Steve and I chat, I recall that the Shubert was the theater that A Chorus Line went into on it's Broadway run, and that I would venture that these AT dimmers replaced the existing DC dimmers when the theater converted to AC for ACL. That places the install possibly at 1975'ish.
Converting to AC meant that you either A) Go to autotransformers or B) Convert to 100 amp capable SCR dimmers and associated control system. Or C) Convert every branch circuit to a single 15 amp SCR circuit with associated control system.
Even now, 38 years later, 100 amp SCR dimmers, while "doable" are not always the best solution (for reasons I've never determined).
As well, I doubt that ANY electronic control system installed in '75
The Shubert Organization has a warehouse in NYC that contains extra and stored away for future use, AT dimmers just for this eventuality, of the dimmers failing over time, in this case, 37 years later.
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