The function can be enabled and disabled with the Operation setting. The corresponding parameter values are "On" and "Off".
The operation of LOFLPTUC can be described using a module diagram. All the modules in the diagram are explained in the next sections.
Level detector 1
This module compares the phase currents (RMS value) to the set Start value high setting. If all the phase current values are less than the set Start value high value, the loss of load condition is detected and an enable signal is sent to the timer. This signal is disabled after one or several phase currents have exceeded the set Start value high value of the element.
Level detector 2
This is a low-current detection module, which monitors the de-energized condition of the motor. It compares the phase currents (RMS value) to the set Start value low setting. If any of the phase current values is less than the set Start value low, a signal is sent to block the operation of the timer.
Timer
Once activated, the timer activates the START output. The time characteristic is according to DT. When the operation timer has reached the value set by Operate delay time, the OPERATE output is activated. If the fault disappears before the module operates, the reset timer is activated. If the reset timer reaches the value set by Reset delay time, the operate timer resets and the START output is deactivated.
The timer calculates the start duration value START_DUR, which indicates the percentage ratio of the start situation and the set operating time. The value is available in the monitored data view.
The BLOCK signal blocks the operation of the function and resets the timer.