Ferroresonance protection device for instrument transformer
AFR 31
KMB Systems
Smart Load to Reduce Ferroresonance
The AFR 31 Smart Load is an instrument designed to protect metering voltage transformers against adverse effects of ferroresonance in high voltage power distribution systems with ungrounded or indirectly grounded neutral wire. Unlike other methods, it is targetedly enabled only when ferroresonance occurs, being passive in common operation or with nonsymmetrical loads, under normal circumstances the this does not load the metering system.
Ferroresonance comes up between transformer inductance and conductor. Connecting, disconnecting, ground connection or other transitional effects may be the trigger events. Ferroresonance oscillations cause significant overvoltage and current surges as a result in very high transformer magnetic circuit saturation. This most often leads to the destruction of instrument transformer.
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