Monitoring and Control System for Mesh Type Grounding Resistance in Medium Voltage Portal Substations

Grounding is essential for the safety of people and electrical equipment. in general, the grounding system is only buried without any grounding resistance control system. grounding resistance can change slightly according to the season, because during the rainy season the soil becomes moist, and vice versa, during the dry season the soil conditions become dry and cause an increase in grounding resistance. In this research, a device is designed that can monitor and control grounding resistance automatically, by injecting water into the grounding location. The control used is Hysteresis ON/OFF type. The device is designed with the specifications of resistance measuring area 0.1 - 500 W, and effective error < 1 %. The resistance measurement method uses the 3-pole fall of potential method. The constant current source used is 10 sin ωt (mA) with a frequency of 128 Hz. The setpoint can be set to 3 - 500 W, with a hysteresis of ± 0.5 W. The data storage speed can be set to 1 - 60 data per minute and stored as a text file (DATALOG.txt). This tool was developed in the LabVIEW environment. The constant current source uses NI-9174 and NI-9265 cDAQ. The controller uses NI MyRIO-1900. As a result of realization and test, the device functions and can significantly control the grounding resistance with an effective resistance measurement error of ± 0.697%. The grounding resistance behavior can be monitored in the form of numerical and graphical data by time, via wireless on the host computer and client.