| ILE: SPOTLIGHT | Buffer Section Switched Off but being re-energized by crane coming from the left Energized Main Runway Adjacent Crane
Crane Under Maintenance – Still grounded, even with the adjacent crane energizing the buffer zone
FIGURE 3. Buffer Zone Being Energized by Adjacent Crane
Position 1 - Complete runway is powered.
(some models substitute air gaps with insulating materials at the two isolation points). It is important to have a second isolation point gap
beyond relying on powering down the middle section. Even with the power shut off to the middle section, a tandem (double-headed) current collector from an adjacent live crane coming from the left can potentially bridge the first gap and re-energize the buffer zone. By moving the crane into the far right section past the second isolation point gap (see correct switching system below), it will remain powered down even if another crane accidentally energizes the buffer zone.
MAINTENANCE ZONE SWITCHING SYSTEM Conductix-Wampfler recently introduced a maintenance zone switching system called “PowerGuard.” PowerGuard correctly switches off power to the buffer and maintenance zones, then grounds the maintenance section to create a safe zone. “PowerGuard was created to provide a truly safe solution to
removing power from areas of crane runways,” said Stephanie LaFarr, a product manager with Conductix-Wampfler. “Previous solutions were not specifically created for the crane market. Terefore, they didn’t offer true isolation of power, leaving a window for error that could result in severe injury or death.” Te system increases user safety by providing visual LED indications and test points at the PowerGuard panel. Tese LEDs are tied to the maintenance zone wiring and show the maintenance team that the maintenance zone is de-energized before beginning any work. Te PowerGuard switches within the switch panel distribute
power to the various PIS segments. With all switched “on”, power flows from the power feed connected to the main runway to the buffer zone, and finally to the maintenance zone. Each of the three switch positions has a specific function.
IN SWITCH POSITION ONE Power flows from the main runway to the “buffer zone” and the “maintenance zone.” When the maintenance team wants to work on the last crane on the runway, they move it into the maintenance zone at the far right end.
FIGURE 4. Diagram of the inside of a PowerGuard Control Box.
IN SWITCH POSITION TWO Power is turned off to both the buffer zone and the maintenance zone.
Position 3 - Maintenance zone is grounded.
Position 2 - Powered is removed from the buffer and maintenance zones.
IN SWITCH POSITION THREE Te maintenance zone is grounded, but the buffer zone is not. Having the buffer zone and using the correct switching sequence is critical for creating safe maintenance zones since a “live” crane moving too close to the maintenance area can accidentally energize the buffer. If this happens, and the switches are properly wired and sequenced, the maintenance zone will stay grounded. A maintenance zone solves common problems associated with maintenance, especially for systems that run multiple cranes on a single runway. Adding a maintenance zone switching system like PowerGuard provides a safe solution for conductor bar applications, and allows for maximum crane uptime while protecting both people and equipment.<
Conductix-Wampfler is a leading global provider of energy and data transmission solutions. To learn more about their products or for contact details, visit their website at
www.conductix.com
INDUSTRIAL LIFTING EXCHANGE
SUMMER 2018
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