Four 35-year-old transformers were replaced with two more efficient new ones, ensuring reliability to handle additional power loads and allowing electricity generated by the brakes of the railroad's new fleet of M8 rail cars to be fed back into the power grid.
The substation sits in an area surrounded by a chain link fence that also was replaced with a more secure fire wall as part of the $5- million project. One new transformer was installed at Mount Vernon last fall and was adequate to serve the power needs of the line. The second new transformer was installed and cut over this past weekend bringing redundancy to the system.
The remaining work entails completely replacing the remaining components of the substation, including replacing the secondary switchgear at New Rochelle, supplementing underground feeder cables from Mt. Vernon to New Rochelle with aerial, high tension wires, replacing the existing signal substation and installing a new circuit breaker house at Pelham.
In March, a similar upgrade was completed, doubling the capacity at the Cos Cob West substation. The railroad was then able to deliver power to the New York segment of the New Haven Line from Cos Cob through an upgraded tie system at the Harrison and Rye switching substations. This contingency was available but not needed during the recent installation.
The Con Edison power supply into the substation is 138 kilovolts, which the transformers step down to 27 kilovolts in order to feed the overhead catenary wires that supply electricity to the trains.
The project allows Metro-North to use the regenerative braking technology on its newest rail cars, the M8s, to feed power back into the catenary system each time the cars go into braking mode. This excess electricity reduces Metro-North's overall power demand. To take advantage of this potential power savings, the existing controls and metering at the Mount Vernon East substation are also being reconfigured.