Unit 36 Mock Exam

An inductor of 300mH placed on a 60Hz network will have an inductive reactance of?

A capacitor of 90µF is placed on an electrical network of frequency 65 Hz. What is the value of capacitive reactance?

What is the typical generation voltage at a power station?

Where is the neutral connected on the secondary of a delta to star transformer?

What is the phase separation angle in a typical star system between phases?

A voltage of 700V is applied to two resistors in series. A current of 2.8A flows. If one of the resistors is 150Ω what is the value of the other?

What is the series impedance of a circuit where the resistance is 30Ω the inductive reactance is 70Ω and the capacitive reactance is 30Ω?

If you have a star phase voltage of 135V what would the line voltage be?

A 30kW lift motor is running at 0.95 power factor. Calculate the line current that is drawn from the supply when the voltage is 390V:

What type of light fitting requires no control gear?

Which type of protective device natively offers the functions of earth fault, residual current and short circuit protection?

A light source of 300 Candela is placed 2.5m above a table. Calculate the illuminance at a point directly below the light fitting.

The full load current of a transformer is 650A and the voltage is 400V between phases. Calculate the apparent power rating of the transformer.

In a TT system the means of earthing is provided by:

The phase voltage supplied to a building is 270V. The building is given a 3 phase 3 wire supply. What voltage are available to work with?

Calculate the angle the current lags the voltage in a network where there is 30kW and 12kVAr on the network.

A centre tapped to earth transformer has a voltage of 75V phase to earth. What would the full voltage available be?

A 25kW load is being drawn from a supply at 350V. Calculate the power loss through the conductor if the resistance is measured at 0.3Ω.

The potential difference between a cat and the earth is 1000V. If the resistance of the cat is measured at 250Ω what would the current flow to earth be?