Application 

The REF601 and REJ601 are protection relays aimed at protection and control of incoming and outgoing feeders in MV distribution substations. 

They can be applied for short-circuit, overcurrent and ground-fault protection of 

overhead lines and cable feeders of distribution and sub-distribution networks.

The inrush current stabilization function allows the relays to be 

used as the main protection for distribution transformers.

The relay with application configuration B offers non-directional 

overcurrent and ground-fault protection. The residual current for 

the ground-fault protection is derived from the phase currents. 

When applicable, core-balance current transformers can be 

used for measuring the residual current, especially when sensitive ground-fault protection is required.

The application configuration C adds thermal overload protection for feeders, cables and transformers, phase discontinuity 

protection and circuit breaker failure protection.

The application configuration D provides the highest functionality with incorporation of negative 

phase sequence protection and a multi-shot auto-recloser function making the relay suitable for overhead line feeders.