Will the phase loss relay, RM5TF30 change state on phase loss if there is a substantial backfeed?
Measurement Relays - GIC Product
Product Operation and Characteristics
If a phase loss occurs and there is substantial backfeed to the relay, it is possible that the relay could be fooled into thinking that all three phases are present on a circuit. Under typical applications, the "missing leg" would be of a voltage that is significantly different from the other present legs. With tight enough thresholds, the relay can be set to change contact state just from the imbalance itself.