Implementation of Smart Features for a New Generation Air Insulated Switchgear

Abstract

Air insulated switchgear mainly consists of circuit breaker and switches. It is used for switching and protection of the electrical equipment. Monitoring of switchgear parameters such as excess temperature rise of critical parts, improper contacts of fingers, insulation breakdown or humidity above permissible limits is important as this can lead to complete failure of the product and the system. This thesis presents implementation of some smart features such as continuous thermal and humidity monitoring in AIS. Thermal sensor is implemented for continuously monitoring the temperature of hot spots in switchgear, indicating temperature rise above IEC standard limits during the normal working condition. The thermal sensor (Easergy TH110) is a wireless and battery less sensor with energy harvesting and communicates using ZigBee Green Power (ZGP) wireless communication protocol. The sensor has been tested and data generated from the test is analysed. Wireless humidity measurement system is developed on arduino platform to continuously monitor the humidity levels in switchgear. The system communicates the measured value to the receiver using ZigBee wireless communication protocol at 2.4GHz. The data generated from this system is analyzed graphically on the GUI developed on MATLAB, thus keeping a constant eye on humidity in switchgear. The simulations carried out in NS2 draw a comparative study of ZigBee and ZGP in terms of energy consumption of nodes. This concludes that the average energy consumed by a node is considerably less when communicating with ZGP compared to ZigBee, proving it to be a better solution for wireless sensor networks in switchgear. Another feature implemented is the Universal Coil. It is a standard coil capable of handling auxiliary supply voltages in the range of 20V to 242V DC and 20V to 253V AC. The electronic card used with this coil is designed to give a constant 12V DC to the closing and tripping coils. The card is developed, tested and implemented in switchgear to overcome the issue of coil replacement for different supply voltages.