The function can be enabled and disabled with the Operation setting. The corresponding parameter values are "On" and "Off".
The operation of JAMPTOC can be described with a module diagram. All the modules in the diagram are explained in the next sections.
Level detector
The measured phase currents are compared to the set Start value. The TRMS values of the phase currents are considered for the level detection. The timer module is enabled if at least two of the measured phase currents exceed the set Start value.
Timer
Once activated, the internal START signal is activated. The value is available only through the Monitored data view. The time characteristic is according to DT. When the operation timer has reached the Operate delay time value, the OPERATE output is activated.
When the timer has elapsed but the motor stall condition still exists, the OPERATE output remains active until the phase currents values drop below the Start value, that is, until the stall condition persists. If the drop-off situation occurs while the operating time is still counting, the reset timer is activated. If the drop-off time exceeds the set Reset delay time, the operating timer is reset.
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.
Blocking logic
There are three operation modes in the blocking function. The operation modes are controlled by the BLOCK input and the global setting which selects the blocking mode. The BLOCK input can be controlled by a binary input, a horizontal communication input or an internal signal of the protection relay's program. The influence of the BLOCK signal activation is preselected with the global setting Blocking mode.
The Blocking mode setting has three blocking methods. In the "Freeze timers" mode, the operation timer is frozen to the prevailing value. In the "Block all" mode, the whole function is blocked and the timers are reset. In the "Block OPERATE output" mode, the function operates normally but the OPERATE output is not activated.