Abb manufacturers as well as supplies various types of voltage relays that are most used relays for voltage protection. List of different modes of voltage relays are as follows:
1 spau 110 c - earth fault protection & supervision in isolated neutral, resistance earthed or reactance earthed networks
2 spau 130 c - three-phase voltage relay for over- & under voltage protection & supervision in distribution substations
3 spau 320 c - busbar phase-to-phase voltage & residual voltage
4 spau 331 c - busbar voltages in distribution network
5 spau 121 c - over- and under voltage protection & supervision in distribution substations
6 spau 140 c - synchro-check relay for voltage measuring when two power systems are to be connected together
7 spau 330 c - busbar phase-to-phase voltage & residual voltage
