Network Protector
An automatic switching device on secondary network systems preventing reverse power flow from distributed generation sources.
A network protector is an automatic circuit breaker with reverse-power relay on the secondary (LV) side of distribution transformers in spot or grid network systems. It connects the transformer to the secondary bus when primary power is available and opens when reverse power flow is detected.
Critical for systems with distributed generation (solar PV, energy storage) where inverters can backfeed through de-energized transformers. Prevents islanding and protects personnel.
Operating principle: reverse power relay detects flow direction; breaker trips within 1–2 cycles. Must coordinate with LV protection and ground fault systems.
QDTB integrates network protector functions in prefabricated substations for urban network applications. See new energy guide for DG integration.
Related Products
Related Terms
More Terms Starting with “N”
No-Load Loss
Power consumed when energized but not supplying load, consisting of core losses (hysteresis + eddy currents).
Neutral Point
The common connection point of a star (wye) winding where the three-phase voltage vector sum equals zero.
NEMA Rating
Enclosure protection ratings for electrical equipment specifying protection against environmental hazards.
Nameplate Rating
Manufacturer's certified specifications on the transformer nameplate defining all critical parameters.
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Buchholz Relay
A gas-actuated protective relay between transformer tank and conservator detecting internal faults by sensing gas accumulation.
Lightning Arrester (Surge Arrester)
A protective device diverting high-voltage surges from lightning and switching to ground, safeguarding transformer insulation.
Relay Protection (Transformer)
Protective relay schemes detecting transformer internal and external faults, initiating circuit breaker tripping to isolate faults.
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