Inrush Detector (81Hbl2) - Siemens Reyrolle 7SR46 Manual

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Applications

5.6 Inrush Detector (81HBL2)

5.6

The inrush detector (81HBL2) element detects the presence of high levels of 2

cates a transformer inrush current during switch-on. The inrush current raises above the operate level of the

overcurrent elements for a short duration. It is important that the relay does not issue an incorrect trip

command for this transient network condition.

If a magnetic inrush condition is detected, then operation of the overcurrent elements can be blocked.

The calculation of the magnetizing inrush current level is complex, however a ratio of 20% of the 2

to the fundamental current meets most applications without compromising the integrity of the overcurrent

protection.

When the inrush detector (81HBL2) is active, if the current crosses the 81HBL2 Release Block setting,

then the relay issues the trip command and provides the fault and event records based on the protection func-

tion I

setting and the current magnitudes.

NOTE

When the 50LC Inrush Action is enabled, the 81HBL2 Release Block setting must be greater than

the 50LC Setting.

harmonic current, which indi-

harmonic

Reyrolle, 7SR46 Device, Manual

C53000-G7040-C103-1, Edition 10.2022

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