3kV DC/25kV AC Transition

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Rob Jamieson
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3kV DC/25kV AC Transition

Post by Rob Jamieson »

When the line from Beaufort West to De Aar was electrified many years ago, they used 25kV AC 7E locomotives on the route. The trains from Cape Town to De Aar were hauled by 4E, 5E, 5E1 and 6E1 3kV DC locomotives. At Beaufort West, the 3kV DC locos would uncouple and proceed to the loco shed. Only once these locos were out of the section, would the line be energised with 25kV AC power and the 7E locos would then enter the section, couple up to the train and proceed to De Aar. Now that you have 14E's (dual 3kV DC/ 25kV AC locos) operating all the way through from Gautang to the Cape, I was wondering how the transition of the power now works. Must the 14E locos lower their pantagraphs and wait for the power to be switched before extending the pantagraph again to draw power from the new current.
Rob
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Rob Jamieson
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Re: 3kV DC/25kV AC Transition

Post by Rob Jamieson »

Anyone got any ideas on this one.
Rob
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Al Brough
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Re: 3kV DC/25kV AC Transition

Post by Al Brough »

Hi Rob,

From research that I have done on the matter, I can safely guess that they can switch without having to lower their patograph.

http://en.wikipedia.org/wiki/South_Afri ... cteristics

"is a dual voltage locomotive, designed to operate on either 3 kV DC or 25 kV AC and it is equipped with onboard voltage detectors."

With current technology it wouldn't suprise me if it happened in a split second.
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John Ashworth
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Re: 3kV DC/25kV AC Transition

Post by John Ashworth »

Welcome to the FOTR Forum, Al. Looks like you're interested in modelling, so we hope to hear a lot more from you on that subject.
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Rob Jamieson
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Re: 3kV DC/25kV AC Transition

Post by Rob Jamieson »

Thanks Al, it makes sense.
Rob
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Al Brough
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Re: 3kV DC/25kV AC Transition

Post by Al Brough »

Hi John,

Pleasure to be aquainted. I hope to learn as well as pass on what I know. I really enjoy watching what FOTR does for old stock to keep memories alive.

Al
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Al Brough
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Re: 3kV DC/25kV AC Transition

Post by Al Brough »

Found this info on wikipedia about TGV's that use different power sources

TGVs have two pairs of pantographs, two for AC use and two for DC use. When passing between areas of different supply voltage, marker boards remind the driver to turn off power to the traction motors, lower the pantograph(s), adjust a switch to select the appropriate system, and raise the pantograph(s). Pantographs and pantograph height control are selected automatically based on the voltage system chosen by the driver. Once the train detects the correct supply, a dashboard indicator illuminates and the driver can switch on the traction motors. The train coasts across the boundary between sections

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Al
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Derek Walker
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Re: 3kV DC/25kV AC Transition

Post by Derek Walker »

There was a youtube vid floating around of an Indian loco transitioning between 2 different voltage sections, you could see him drop the panto and coast along before raising it again, I dont know what had to be done inside the cab though.
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Rob Jamieson
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Re: 3kV DC/25kV AC Transition

Post by Rob Jamieson »

Thanks to you all for your inputs. I've just realised that this type of transition does not only take place at Beaufort West, but must also take place at quite a few places like Kimberley, Beaconsfield and Pyramid, amongst others wherever 3KW DC tracks meet 25KW AC tracks.
Rob
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Jacob Ossebaar
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Re: 3kV DC/25kV AC Transition

Post by Jacob Ossebaar »

As a employee of the Dutch Railway ,i would explane some things .
THE NMBS have a locomotive for the TEE Amsterdam- parijs , for the electric systeem 1500 volt / 3000 volt DC or 25 kV AC . Between Rosendaal ( NS 1500 V DC ) and Essen ( NMBS 3000 V dc ) are the whire about 50 meters manco . On the loco the electric installation , was 1500 V DC Example the 4 tracionmotors are on the 1500 volt 2 x 2 groups on serie-parallel and on the end al the motors parallel . On the 3000 v ,first 4 motors on serie ,and on the end 2 x 2 serie-parallel . . on the 25 kv al the enegie via trafo , 25 kv AC -3000 v DC . Each Voltage an one pantograaf , special for the lichtraum profile . The locodriver switch on the switchingpanel the right Voltage .
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