The function starts when the measured current exceeds the breakdown torque level,
that is, above the set limit. The operation characteristic is definite time.
The function contains a blocking functionality. It is possible to block the function
outputs.
4.1.7.4 Operation principle
The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of the motor load jam protection can be described with a module
diagram. All the modules in the diagram are explained in the next sections.
GUID-93025A7F-12BE-4ACD-8BD3-C144CB73F65A V2 EN
Figure 121: Functional module diagram
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.
1YHT530004D05 D Section 4
Protection functions
615 series 241
Technical Manual
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