04/19/2012 | Editor: Marcel Dröttboom
To solve heavy load issues in the motor control of conveyor systems, Eatons Electrical Sector offers a combination of the PKE motor-protective circuit-breaker and the SmartWire-DT communication system.
The result is comprehensive indication functions and extended drive monitoring, even under tough conditions. Unnecessary outages can be prevented. According to Eaton, the advantage of the PKE motor-protective circuit-breaker compared with conventional solutions lies in the expanded drive monitoring. The diagnostic, status or overload messages show the actual flow of current and display the status of the overload trip device. The actual motor current can be continuously displayed and analyzed via Eaton’s “SmartWire-DT”, the cost-optimized communication system for switchgear, without additional components. Depending on the drive application, the following operating states can be differentiated: motor switched off, motor underload, motor no-load, motor operation, motor overload and motor fault. The separate load limits and the time response behavior can be individually programmed and adapted to all drive tasks. Emerging faults can be identified in good time thanks to the transmission of motor current and overload status. This enables the system operator to intervene in the production process before an undesirable interruption occurs. Of particular interest in this case is the option to operate the PKE as a motor protection relay. The motor-protective circuit-breaker is then not triggered in the event of overload; only the associated contactor is disconnected. Once the overload situation is rectified, the motor can be switched on again via the control unit without the maintenance personnel having to first reset the protection switch
Frozen elevating conveyors and typical belt conveyor scenarios when transporting coarse bulk material can only be insufficiently tracked in conventional drive control systems, as individual motors or belts at standstill are only indirectly interpreted via the switching states of the motor-protective circuit-breaker and power contactor. A hardware solution such as a speed sensor, load-shedding relay etc. is additionally required for a specific, reliable response. In the event of overload, the drive is immediately disconnected when the set current value is exceeded and a fault is signaled to protect the motor from being destroyed. This results in unscheduled, time-consuming and costly downtimes because conventional analog I/O technology cannot image the current motor current as continuously and in such detail as the Eaton solution and therefore shuts down more often than necessary.
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