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SCENECONTROL 500 OPERATING INSTRUCTIONS
Design, Manufacture and Installation of Theatrical Equipment Worldwide
(315) 451-3440
Fax (315) 451-1766
www.jrclancy.com
Rev 1: February 15, 2007
Load Sensing
Background
Load sensing is a powerful feature that is incorporated into some Scenecontrol systems. The load sensing
system takes in load information from load cells that are built into the winch system, and processes that
information to stop winch operation in response to sudden load changes, such as would occur if a batten or
set catches on or lands on an obstruction.
A batten hoist system may seem fairly simple to a theatre person. The loads imposed on such a system are,
in fact, rather complicated. Each system incorporates a number of separate lines, running through separate
pulleys, attached to different points in a building, and bearing different amounts of weight. The weight of the
system changes as the batten moves (due to the changing length of wire rope). Even in a variable-speed
system with gentle acceleration and deceleration ramps, there are major fluctuations in the measured load at
the start and stop of each move. As a consequence, load sensing uses a number of complex algorithms to
integrate and act on this information. The process of gathering this information is called “Load Learning”.
Load Learning
Every time the load on a set is changed, the load profile must be re-learned by the system. This must be
done by an operator logged in with System Level privileges.
Once logged in with System Level password privileges, the operator goes to the System Config window and
touches the Sets button to get to the list of sets. To initiate load learning, the operator touches the desired set
to highlight it, then touches the Load Learn button. Now return to the main operating page, select the
selected winch, and operate it. The best operating sequence for load learning involves running the winch
through successive up and down moves near each end of its travel. If the winch is variable-speed, the speed
should be varied during the test runs to simulate actual anticipated moves. Once these runs are completed,
the operator returns to the Sets page, touches the set to highlight it, then touches the Load Sense button.
Once load sensing has been turned on, it is advisable to test the operation of the set. Returning to the main
operating page, select the winch and run it up and down to assure that it can be run without false tripping.
Once this is assured, test the load sensing by running the winch into a test obstruction to assure that it stops
on a load fault. The fault can be reset from the System Config window by touching the Reset Faults button.
