Switchgear And Protection MCQ For TANGEDCO and TRB Exam With Explanation Part-1
1. The Following Statement Is Associated With The Buchholz Relay Is Not True (A) It is a gas actuated device (B) It is a current operative device (C) It is placed between the transformer tank and the conservator (D) It causes alarm for minor fault and tripping for major fault Answer.: (B) It is a current operative device Explanation:– The Buchholz relay is a gas operated relay used for the protection of oil immersed transformers against all the types of internal faults. The slow developing faults called incipient faults in the transformer tank below oil level operate Buchholz relay which gives an alarm. If the faults are severe it disconnects the transformer from the supply. It uses the principle that due to the faults, oil in the tank decomposes, generating the gases. The 70% component of such gases is hydrogen which is light and hence rises upwards towards conservator through the pipe. Buchholz relay is connected to the pipe, as shown in Fig. Due to the gas collected in the uppe...