Hi all,

Why was the trolley wire on the ground?
Did the truck/trailers bring it down??

Bob in Perth


From:tramsdownunder@... tramsdownunder@...> On Behalf Of Mal Rowe
Sent: Thursday, 11 August 2022 9:25 AM
To:tramsdownunder@...
Subject: Re: [TramsDownUnder] Power supply mysteries

On 11/08/2022 01:17, TP wrote:
Does anybody know the total output of Melbourne's substations and what is the issue that leads to the calls to build more substations, or, alternatively, the decision to fit batteries to the G class to help with power peaks?

Further to Matthew's response, which I mostly agree with:
* The total annual power consumption for Yarra Trams is of the order of 255,000 megawatt hours. They buy that amount of power from two solar farms - leading to their claim to be 100% carbon neutral in terms of power consumption.
* The combination of the air con and the motors drawing maximum load when the doors close and the tram starts up on a hot day produces peak spikes of demand.
* Modern trams are more sensitive to voltage drop. Whereas in 'the old days' all that happened was that the tram was slow and the lights dimmed, modern control electronics shut down when the voltage drops below a certain level.
* The batteries on the G class are a source of 'local energy' that reduces the size of the current spike drawn from the overhead. That means less voltage drop at the tram and les likelihood of the substation being overloaded.
I was told that when Yarra planned to run the E class out to Bundoora they ran a test on a Sunday. They took three Es out to Bundoora and started them all at once. Not one, not two, but three substations overloaded and dropped out.
Mal Rowe attaching dash cam vision of the fireworks when a trolleywire hit the rails