The GKM & GKT Series Voltage Protection Relays are designed to protect electrical equipment from overvoltage and undervoltage conditions in both single-phase and three-phase systems. With flexible configurations and optional phase sequence protection, this series provides a complete solution for. The Type GKC is a drawout case relay with adjustable pickup current and time delay settings to provide time-current coordinated ground fault protection. ABB Type. Our Innovation, Your Solution. Overvoltage, low-voltage, absence of phase, faults in phase order are identified. These are used in devices that operate at sensitive voltage levels.