Figure 20: Thermal curve modification
Motor manufactur
ers and end users are aware of the limitation of the stator thermal model, but the possible
solution to oversize the machine is expensive.
The P24xM relay incorporates a feature where the thermal curve can be modified to overcome this problem.
Previously, the relay had a dual time constant (T1 and T2) characteristic for applications such as star/delta starting.
In this example T2 was set to a lower value than T1. To enable a hot re-start, for a DOL machine, you can set T2 to
a higher value than T1 to avoid the starting characteristic. This is shown in the figure above.
Chapter 6 - Current Protection Functions P24xM
82 P24xM-TM-EN-2.1
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