Thanks Mal, always interesting. I think it’s normal to use hourly ratings for loads when calculating current demand, as I reach back into memory of my trade course. You are taught all sorts of things that are rarely needed in the normal course of events, so they become vague in recall.
As for a bit more on what is and what isn’t a PCC, the 1951 Boston “Picture Window” cars, built by Pullman-Standard, are generally considered “PCC” cars but have PCM camshaft control like the 1949 Red Arrow cars, built by St Louis Car, which aren't considered PCCs. The Boston cars do have B3 trucks and 55hp 300v motors. The Picture Window cars could MU with each other, but not with the earlier “real” PCCs.
Tony G
> On 18 Aug 2017, at 2:01 pm, Mal Rowemal.rowe@... [TramsDownUnder] TramsDownUnder@...> wrote:
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> On 12/08/2017 4:43 PM, Tony Gallowayarg@... mailto:arg@aapt.net..au [TramsDownUnder] wrote:
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>> That 100hp rating for motors is the continuous rating. Short time overloading would see a motor that size putting out up to 150hp for brief time periods, with the resultant high current draw, which a controller in good condition could cope with.
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> Hi Tony,
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> Craig Tooke has provided some more info on the GE controller ratings. He wrote to me as follows:
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> The story behind that table you put on TDU is it comes from a controller publicity pamphlet put out by GE in the 1920’s.
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> The ratings given in the table are for 1 hours continuous and based on a duty cycle of speed 2 mph/s max speed 18 mph and 6x 15 seconds stops per route mile. Using this data and comparing it against traction motor curves an appropriate size of traction motor HP and this is then compared to the rating of the controller and the selection made. The only other thing that is needed to select the type of controller is the number of notches in series and parallel. This is of course determined by means of calculation in the usual manner.
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> Hope you find this further background interesting.
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> Thanks Craig,
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> Mal Rowe
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