| ILE: SPOTLIGHT |
OVERHEAD CRANE MAINTENANCE ZONES Safely Maintain Cranes without Sacrificing Productivity
BY:PETE KIRST, MARKET DEVELOPMENT MANAGER, OVERHEAD CRANES, CONDUCTIX-WAMPFLER AMERICAS
R
outine overhead crane maintenance and repairs are critical for the long-term safety of personnel and longevity of the equipment. However, operators that run multiple cranes on a single runway must be able to shut down one crane while keeping the others running. Fortunately,
this situation can be solved by creating one or more “maintenance zones” on the crane runway system.
WHAT IS A CRANE MAINTENANCE ZONE? A crane maintenance zone is a designated area on the conductor bar runway that is powered down while the rest of the runway remains energized. However, isolating an area of a conductor bar is not as straightforward as it seems. Te setup requires a special series of conductor bar components and a properly wired switching system that will keep the maintenance zone from being accidentally energized by the other cranes still in operation.
A properly installed and wired maintenance zone will:
• Disconnect power in the zone while leaving the main part of the runway energized
• Keep the power off, even if an adjacent crane tries to move into the maintenance zone
• Have a properly grounded maintenance zone that will prevent the crane from becoming energized, and people from being electrocuted
Te solution is to add an electrically-isolated “buffer zone” before the maintenance zone. A typical right-end maintenance zone has a buffer zone in the middle, and the main line power zone on the other side. Additionally, one or more maintenance zones can be established at any point on the conductor bar runway, and buffer zones are then established on either side of the middle maintenance zone.
Air Gap Cross Section 30 SUMMER 2018 INDUSTRIAL LIFTING EXCHANGE
FIGURE 1. End Maintenance Zones – On the right side
HOW DO YOU INSTALL A MAINTENANCE ZONE?
Te first step to install a maintenance zone like the one shown above is to add a “power interrupting section (PIS)” into each of the three phase legs of the conductor bar runway’s right end. A PIS consists of three special conductor bar segments each with a center power feed point (shown in black below). Two 1/2” air gaps electrically isolate the middle section
Center Power Feeds
FIGURE 2. Power Interrupting Section
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