CSI designs and manufactures Pure Digital Fiberlink® fiber optic transmission systems for video, audio and data, Scan Do® scan converters, Deuce® video scalers and more!
Fiber in Action
Fiberlink® Fiber Optic switches keep the current flowing for Metro North
Most riders traveling from New York City’s Grand Central Terminal to points northeast simply hop on a Metro North train and pay little attention to what’s making their train go. However, as any train-loving child will quickly notice, the overhead electric line, or “cantenary system,” that powers the train doesn’t begin until Pelham, New York, just west of the Connecticut border. Between Grand Central and Pelham, the train derives power from elsewhere – an electrified third rail. To Metro North riders, the transition between power sources is seamless. But that doesn’t mean that it’s simple to accomplish.
The third rail system, used between Grand Central and Pelham, operates on 600 volts DC current. The cantenary system, extending from Pelham to New Haven, Connecticut, uses 13,500 volts AC. Given the incredible amount of electricity traveling from the electrified wire down through the pantograph to the train, it is imperative that each car posses a completely isolated mechanism to safely switch between power sources. A car barreling toward New York City with an extended pantograph could be catastrophic as it passes below countless bridges and near neighboring power lines.
On M6 and M4 type cars, the solution is a Fiberlink fiber optic switch, manufactured by Communications Specialties, that monitors the “down and latched” condition on the pantograph of each car. As each car approaches the end of the cantenary system, its pantograph is triggered to move to a “down and latched” position. When the pantograph is properly in place, a Fiberlink transmitter sends a signal over fiber optic cable from the roof of the car down into the DC/AC changeover unit located within the car itself. The very nature of fiber optic transmission ensures that the transmission link is completely immune to possible electrical interference from the pantograph on which the transmitter is mounted. Only when the fiber optic receiver senses a signal will the power automatically switch over to DC. The reverse process occurs for trains traveling in the opposite direction.
The MTA has been using Fiberlink fiber optic switches on its M6 and M4 trains for approximately 15 years.
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Version 1.2 | 3/2/08
