MGVCL Exam Paper (30-07-2021 Shift 2)
A 1000 kVA ONAN cooled transformer has a load of 500 kVA throughout the day except for a period of 4 hours. What is the permissible overload for a duration of four hours. Assume the permissible load kVA as a fraction of rated kVA is 1.24.
Buchholz relay is gas operated relay. It will operate when internal fault occurs in transformer. It is placed between tank to main conservator. It has two contacts trip and alarm. Use of Buchholz relay in distribution transformer is not economical.
Equivalent resistance of the circuit, Req = (12||18) + 8 Req = 7.2 + 8 Req = 15.2 ohm Source current = current through 8 ohm resistor, I = Vr/R8 I = 20/8 I = 2.5 A Supply votage V = I*Req V = 2.5*15.2 V = 38 V
A thermopile is an electronic device that converts thermal energy into electrical energy. It is composed of several thermocouples connected usually in series or less commonly, in parallel. Thermopiles are used for contactless temperature sensing. The function of a thermopile is to transfer the heat radiation emitted from the object to a voltage output. The output is in the range of tens or hundreds of millivolts.
EXAMIANS