Exam (elaborations) Stationary Engineer (ENGINEERING)

AC circuit consists only of a pure inductance and a power source. The relationship between the voltage and the current in this circuit is that the - ANSWERS current lags the voltage The power factor of a load is equal to the ____________ power divided by the ____________ power. - ANSWERS True ; apparent A 10-ohms and 20-ohms resistor are connected in parallel. The total line current drawn by this parallel combination is 30 amps. Under these conditions, the line voltage will be ____________ volts. - ANSWERS 200 A 20-ohm resistor is connected in series with a parallel combination of two resistors, one of which is 10-ohms, the other 40-ohms. If the voltage across the parallel combination is 40 volts, the voltage across the 20-ohm series resistor is ________ volts. - ANSWERS 100 A certain 120-volts single-phase AC circuit has a power factor of 80 percent and a wattmeter reading of 1150 watts. The current drawn by the circuit is _________ amperes. - ANSWERS 12 If the voltage between lines of a 3-phase, 3-wire delta connected system is 2400 volts, then the phase voltage is _____________ volts - ANSWERS 2400 A circuit consists of an inductive reactance of 15 ohms and a resistor of 20 ohms in series across a 100-volts, 60 cycles AC supply. The current in this circuit is ____________ amperes. - ANSWERS 4 A 3 phase, 3 wire, 208 volt, 60 cycles AC service supplies a balanced load consisting of three 30 ohms resistors connected wye. The line current under these conditions os MOST NEARLY ___________ amperes. - ANSWERS 6.9 If the level of the electrolyte in a lead acid storage battery falls below the top of the plates because of evaporations under normal operating conditions, it is BEST to add - ANSWERS Water A 600 volt cartridge fuse must have knife blade contacts if its current rating exceeds _____________ amperes. - ANSWERS 60