EE Review Q4

A circuit consisting of three resistors rated: 10 ohms, 15 ohms and 20 ohms are connected in delta. What would be the resistance of the equivalent wye connected load?

• 0.30, 0.23 & 0.15 ohm

• 3.0, 4.0 & 5.0 ohms

• 3.33, 4.44 & 6.66 ohms

• 5.77, 8.66 & 11.55 ohms

The equivalent wye element of a 3 equal resistors each equal to R and connected in delta is

• R

• 3R/2

• R/3

• 3R

A Barangay power station supplies 60 kW to a load over 2,500 ft, 100 mm2, two-conductor copper feeder, the resistance of which is 0.078 ohm per 1000 ft. The bus bar voltage is maintained constant at 600 V. Determine the load current.

• 105 A

• 108 A

• 110 A

• 102 A

An LRT car, 5 km distance from the Tayuman station, takes 100 A over a 100 mm hard drawn copper trolley wire having a resistance of 0.270 ohm per km. The rail and ground return has a resistance of 0.06 ohm per km. If the station voltage is 750 V, what is the voltage of the car?

• 585 V

• 590 V

• 595 V

• 580 V

The LRT trolley system 10 miles long is fed by two

substations that generate 600 volts and 560 volts,

respectively. The resistance of the trolley wire and

rail return is 0.3 ohm per mile. If the car is located 4

miles from the 600 volt station draws 200 A from the

line. How much is the current supplied by each

station?

• 133.33 A, 66.67 A

• 123.67 A, 76.33 A

• 117.44 A, 82.56 A

• 125.54 A, 63.05 A

In Manila, the LRT runs between Gil Puyat Station

and Tayuman Station, which is 4 km apart and

maintains voltages of 420 volts and 410 volts

respectively. The resistance of go and return is 0.05

ohm per km. The train draws a constant current of

300 A while in motion. What are the currents

supplied by the two stations if the train is at the

distance of minimum potential?

• 175 A, 125 A

• 183 A, 117 A

• 164 A, 136 A

• 172 A, 123 A

An LRT car, 5 km distance from the Tayuman station,

takes 100 A over a 100 mm hard drawn copper

trolley wire having a resistance of 0.270 ohm per km.

The rail and ground return has a resistance of 0.06

ohm per km. If the station voltage is 750 V, what is

the efficiency of transmission?

• 78%

• 81%

• 74%

• 79%

A barangay power station supplies 60 kW to a load

over 2,500 ft of 0002-conductor copper feeder the

resistance of which is 0.078 ohm per 1,000 ft. The

bus bar voltage is maintained constant at 600 volts.

Determine the maximum power which can be

transmitted.

• 220.35 kW

• 230.77 kW

• 242.73 kW

• 223.94 kW

Twelve similar wires each of resistance 2 ohms are

connected so as to form a cube. Find the resistance

between the two diagonally opposite corners.

• 1.45 ohms

• 1.66 ohms

• 2.01 ohms

• 1.28 ohms

Twelve similar wires each of resistance 2 ohms are

connected so as to form a cube. Find the resistance

between the two corners of the same edge.

• 1.133 ohms

• 1.102 ohms

• 1.125 ohms

• 1.167 ohms