Specifications

7SR242 Duobias Applications Guide

2.10.1 Application with Capacitor Cone Units

Capacitor cones provide a cost effective method of deriving residual voltage. The wide range of capacitor cone

component values used by different manufacturers means that the relay cannot be connected directly to the

cones.

The external adaptor unit contains parallel switched capacitors that enable a wide range of values to be selected

using a DIL switch and hence the Capacitor Cone output can be scaled to the standard relay input range.

2.10.2 Derived NVD Voltage

Alternatively NVD voltage can be derived from the three phase to neutral voltages, this setting is available within

the relay. Note with this method the NVD protection may mal-operate during a VT Fail condition.