A Michigan-based sand and stone company was having a problem with slippage on a 190-ft retractable conveyor. The top belt was slipping without warning, resulting in material overflow at the transfer point between the lower and upper section of the belt causing material spillage. A cost-effective solution to warn operators of material build up was desired by the operations manager.
It was determined by Conveyor Components Co.’s engineering department that a low-cost, effective method to solving the company’s problem would be the Model CT tilt level control. Level controls are designed to detect high or low material levels. In this particular application the level control would be able to detect high material levels, or back-up, at the conveyor transfer point. Consisting of a control unit and a probe, the Model CT is often used when other controls won't work due to bin vibration, or actual bin walls aren't available for mounting.
Due to the environment, the Model CT-105 control unit was recommended. The control unit is UL Listed, NEMA Type 4, 4X, and is dust tight and weatherproof for outdoor use. The enclosure is made of durable cast aluminum to resist corrosion, and is equipped with a surface mount printed circuit board that is resistant to shock and vibration. The surface mount PC board has a field-adjustable logic selector switch that can be set to actuate an alarm when material is present or when material is absent. There is an adjustable time delay to prevent false signals. The controller output is a relay that is actuated by the tilt probe when the presence (or absence) of material is detected.
The Model CT-201G heavy-duty probe was recommended to be used in conjunction with the control unit. The 9-in. probe is made of heavy-duty steel. The abrasion-resistant probe is designed to tilt when material piles up high enough to reach it. The probe will actuate when tilted 15° from vertical, and send an alert to the controller, which then signals an alarm through the output relay.
The control unit allows for up to 5000 ft of cable length between the control unit and the probe, which allowed the placement of the control unit at the base of the conveyor. Here, it is easily accessible by personnel, and the red “alarm” and green “normal” LED indicator lights are clearly visible.
Using the CT-400 mounting bracket and CT-500 S-hook, the probe was suspended at the desired indication level in the transfer point chute between the upper and lower leg of the conveyor. The tilt probe was then wired with 16-3 SO cable, item number CT-300G, to the control unit at the base of the retractable conveyor.
When material build up is detected by the probe’s tilt action, the output relay signals for the lower conveyor leg to shut down. The device used in this solution not only alerts the operator there is a problem via the LED indicators, it also halts the material feed and protects the equipment from costly damage.
For more information on Conveyor Components Co. (Croswell, MI), call 800-233-3233 or visit www.conveyorcomponents.com.
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