DT009/2 Fault Analysis J Kearney
A short circuit fault occurs in a power system when equipment fails. This may be
due to system overvoltages caused by lightening or switching surges, insulation
contamination or mechanical failures. The resulting f
Electrical Energy Systems 2.1
DT009 year 2
4 sections, 10 marks each = 40 marks;
Consists of all parts of the course;
(b) Three Phase;
Question 2 4:
A 220/12V, 500VA, 50Hz single-phase transformer gave the following test results:
Open circuit test on secondary side: Ioc = 5A, Poc = 50W;
Short circuit test on primary side:
Vsc = 5V, Psc = 10W.
a) Find the approximate equivalent c
A balanced, three phase, three wire, 190 Volt RST system is connected to a delta load with
ZRS = 1 + j 3 , ZST = 5 and ZTR = 1 j 3 . Find the line currents and illustrate your answer on a
clearly labelled phasor diagram. What is the to
Three Phase Systems
A balanced, three phase load is connected in delta to a three wire, 1 kV, 50 Hz,
balanced RST supply. The supply is connected through a three-phase wattmeter and
one line is connected through an ammeter. Each load consists of
A transformer is modelled by the following losses and connected to a load as shown:
If this transformer is connected to the ESB supply on the primary side (230 V, 50 Hz),
calculate the reading on the ammeter when RL = 1 . If the secondary was
DT009/2 Electrical Energy Systems l Questions. J Kearney
Why does the rotor of an induction motor turn slower than the revolving field?
Describe briefly the key differences between a squirrel cage motor and wound-rotor motor, in
terms of constru
Substation may be defined as an assembly of apparatus installed to perform switching,
voltage transformation, power factor correction, power and frequency-converting
Bus Bars (Copper or Cop
A 220/110V, 2kVA, 50Hz single-phase transformer gave the following test results:
Open circuit test on secondary side: Ioc = 5A, Poc = 400 Watts;
Short circuit test on primary side: Vsc = 30V, Psc = 200 Watts.
Find the approximate equivalent c
A balanced, three phase, three wire, 300V TSR system is connected to a balanced star
load with Z = 1 + j2 . Find the line currents and illustrate your answer on a clearly
labelled phasor diagram. Convert this star system to a delta sys
The Per Unit System.
Power system quantities such as voltages, currents powers and impedances are often
expressed in terms of per unit values, or percentages of specified values.
P.U. quantity =
Taking 20kV as the base volt
DT009/2 Electrical Energy Systems Dr. J Kearney
Three-Phase Induction Machines.
An induction machine is a machine having a wound winding on the stator and a wound or
cage type rotor.
Induction machines are perhaps the most widely used of al