5357 103 recap test

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5357 103 recap test

Try your science skills with this electrical science questionairre......

. Impedance is measured in *

1 point

a. Watts [W]

b. Kilowatts [kW]

c. Ohms [Ω]

d. Amps [A]

Explain in your own words how an mcb operates during a short circuit. *

3 points

An RCD does not operate during a short circuit fault. Explain why. *

3 points

How much current does a 25 Amp B type MCB require to trip instantly?

1 point

30 Amps

125 Amps

200Amps

225 Amps

Clear selection

The symbol for inductance is: *

1 point

Inductance is measured in what unit? *

1 point

a. Bertys [B]

b. Henrys [H]

c. Fredricks [F]

d. Bobbys [BO]

The symbol for impedance is *

1 point

a. Z

b. U

c. L

d. X

Using words, describe the earth fault loop path for a TNC-S earthing arrangement. include the connection points and components parts. *

3 points

How much current is required to instantly trip a 20A D type MCB conforming to BSEN 60898? *

1 point

What is the formula for calculating inductive reactance? *

1 point

2πFL=XL

add the resistance and reactance together

impedance-resistance=reactance

power factor x watts.

What is the purpose of a commutator? *

1 point

To keep the torque on a DC motor from reversing every time the coil moves through the plane perpendicular to the magnetic field, a split-ring device called a commutator is used to reverse the current at that point

to help people get to work?

to reverse the field windings of the stator?

a) State the maximum fuse rating (In) fitted in the D.N.O Service cut out? *

1 point

60A

80A

100A

10A

c) How many live cables enter a single phase domestic property? *

1 point

6. A coil having both resistance and inductive reactance is connected to an A.C supply. Which impedance triangle is in the correct format? *

3 points

Option 1

Option 2

Option 3

Option 4

Option 5

7. A coil of inductance of 0.8H and resistance of 40Ωis connected to a 230V 60Hz supply. Determine, showing all calculations and units of measurements, a) the impedance of the circuit, b) The power factor of the circuit, c) the size of capacitor required in series to correct the power factor to exact unity? *

10 points

8. Calculate the power factor of a 3KW load that draws 18Amps from a 230V supply? *

1 point

1.5

-0.72

0.72

0.73

Explain how the object shown in the picture works *

3 points