New York City —As I slowly climbed the 354 narrow steps that wind around the inside of the Statue of Liberty, I fought a slight case of claustrophobia, overcome by the dizzying view of staircases and catwalks that bridge her hollow inside. It was then that I began to appreciate Lady Liberty's elevator—and quietly resent it, as it continuously shuttled passengers to the top of the pedestal. I was headed for the crown, so I had to walk.
The all-hydraulic elevator is the only assisted access inside the statue. Hundreds of people used it the day I visited, and hundreds more rely on it during the summer, when Liberty's steel siding can act like an oven—keeping even the physically fit from using the stairs. "We need the elevator operating as much as possible," says Jeff Marrazzo, building and utilities foreman at the Statue of Liberty. "We're on an island out here. It takes time for a repair person to get on a boat, diagnose the problem, and then get the tools to fix it. We figured if we could let the maintenance contractor know what the problem was before coming out—like a blown fuse or a burned out relay—we could decrease downtime."
Engineers at Omron Electronics (Schaumburg, IL) custom designed a programmable logic controller (PLC) to monitor and control the elevator. "Because of financial constraints, the Park Service needed to use the existing relay logic," says Dick McDonnell, regional accounts manager at Omron, "but they wanted more information when something did trip up. The Omron CS1 PLC acts as a diagnostic tool."
Picked partly because it has Ethernet capabilities, the CS1 can take an active role in a network. It monitors the motor starters, the leveling switches, and fuses, and keeps track of how many trips the elevator makes per day. The system even has the capability to e-mail the Park Service if maintenance is required—though that feature is not yet used because it is difficult to transmit data within Liberty's concrete base. The PLC is coupled with a touchscreen, a discrete input card, and a thermocouple card to monitor the oil, room, and cabinet temperatures.
"In the summer, temperature used to cause a lot of the failures as the room and hydraulic fluid heated during the day," says touchscreen programmer Jay Hughes, Omron Senior Application Engineer. "The screens help the Park Service schedule preventive maintenance. Now they can gauge how long particular parts will last, how many trips they can make, and how hot they can run."
This particular application also had unique constraints. Since the Statue of Liberty is a National Park, there are strict regulations about its preservation and alteration. "We can't just go drilling holes anywhere we please," says Marrazzo. For example, because they couldn't go through the wall, engineers used an infinitely-adjustable steel arm from STRONGARM Designs (Horsham, PA) to mount the touchscreen to the floor. The arm allows the screen to maneuver around existing structures and be seen from a variety of angles.
"And since downtime is such a concern," adds McDonnell, "a lot of this project—from concept to installation—took place while the elevator was operating. I think I really got the feel for what it's like to be a surgeon."
Did it work? Yes, according to Marrazzo. "The system is an invaluable tool in reducing downtime." You still have to brave the stairs to reach the crown, but it is worth it.
For more information about controllers and touchscreens from Omron Electronics: Enter 539
For more information about positioning arms from STRONGARM Designs: Enter 540