4th Quarter 2009Electrical switching & drive systems & components
“This (Lilly) controller not only guards against overspeed, but imposes the more rigorous control required when riding men and also trips in the event of overwind.”
Thus reads an extract from an article on the introduction of a new Ward-Leonard controller described in a January 1942 issue of Colliery Engineering.
Times change and no longer are “acceleration and retardation adjusted independently by orifice plates which control the rate of oil flow into and out of the servomotor” as the article continues. Software and electronics have taken the place of orifices, rods and cams.
E-Lilly
The Schneider Electric e-Lilly (Electronic Lilly) V2 controller is a PLC-based version of the classical Lilly electromechanical winder safety device and although the technology is vastly different from those early controllers, the intent remains the same: safety of personnel and equipment associated with mine winders.
Schneider has been implementing this solution in conjunction with its Altivar 61 and 71 variable speed drives to provide packaged systems for winder controls at mines in South Africa and abroad.
On electromechanical Lilly controllers the acceleration and deceleration profiles were static, providing a single curve for all operating conditions. In the e-Lilly, profiles can be fully parameterised and dynamically adjusted according to the operating mode (men/rock, men/material and two different kibble winder modes).
Schneider Electric’s e-Lilly system architecture
Systems that learn
The configurability and intelligence of a programmable system means that functionality can be incorporated over and above the basic overwind, underwind and overspeed safety functions.
Dual redundant controllers and relay feedback signals allow the system to be self-checking. An external hardware watchdog monitors the PLCs to ensure they are running correctly. At start-up, the e-Lilly tests each of its output relays to confirm the outputs are changing over as required and all output relays have feedback contacts that are continuously monitored.
Software-based systems facilitate automatic calibration, ensuring that the overwind point will be the same for a full conveyance and an empty conveyance; unaffected by rope-stretch. Systems for kibble winders can be configured so that the stage depth is automatically re-calibrated every time the crosshead makes contact with the stage stopblocks.
Rather than incorporating absolute depth settings, software facilitates the use of depth settings that are configured relative to user-defined anchor depths: if an anchor depth is moved, all depths associated with it, including those related to the protection envelope, will move accordingly. This is of great value on kibble winders where the stage depth and bottom depth are constantly moving.
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