The function can be enabled and disabled with the Operation setting. The corresponding parameter values are "On" and "Off".
The operation of PREVPTOC can be described with a module diagram. All the modules in the diagram are explained in the next sections.
Level detector
The level detector compares the negative-sequence current to the set Start value. If the I 2 value exceeds the set Start value, the level detector sends an enabling signal to the timer module.
Timer
Once activated, the timer activates the START output. When the operation timer has reached the set Operate delay time value, 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 of 200 ms, the operation 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 operation time. The value is available in the monitored data view.