AC Theory Practice(Latest Exam 2024)
In New Zealand, the standard distribution system has the
neutral conductor connected to the earth at the main
switchboard on all low voltage installations. What name is
given to this type of system? - correct
answers✅Multiple Earthed Neutral or MEN system.
State the test voltage used for carrying out an insulation
resistance test on three-phase, 400V, electrical
equipment incorporating MIMS elements. - correct
answers✅500 V d.c.
State the minimum permitted test result for the insulation
resistance test on electrical equipment without MIMS
elements - correct answers✅1MΩ
State the permitted test result for an insulation resistance
test for the electrical installation with all the permanently-
connected electrical equipment connected. - correct
answers✅0.01MΩ
State the minimum permitted test result for the insulation
resistance test on the electrical equipment incorporating
MIMS elements. - correct answers✅0.01MΩ
State ONE precaution that could be taken when using an
insulation resistance tester, set on the 500V d.c. range, to
carry out an insulation resistance test on electrical
,AC Theory Practice(Latest Exam 2024)
equipment containing semi-conductor devices. - correct
answers✅Bridge out between phase and neutral
why you would take this precaution on electrical
equipment containing semi-conductor devices. - correct
answers✅The voltage of the test instrument may
damage semi-conductor devices.
AS/NZS 3000 requires that a test voltage of 500V d.c. is
used for an insulation resistance test of a low voltage
electrical installation. State ONE reason why the voltage
is a d.c. voltage. - correct answers✅Any ONE of:
● To ensure capacitive or inductive reactance does not
influence the test
result.
● A constant maximum voltage is a more
stringent test than the momentary peaks of an a.c.
waveform.
AS/NZS 3000 requires that a test voltage of 500V d.c. is
used for an insulation resistance test of a low voltage
electrical installation. Explain why a voltage of 500V is
applied. - correct answers✅To stress the insulation at a
voltage
,AC Theory Practice(Latest Exam 2024)
above 325V a.c. (or peak a.c. voltage).
Tests have been carried out on a three-phase 400V, Class
I, plug-in electrical appliance after it has been repaired.
The test results are as follows:
Earth continuity test - out of range
Insulation resistance test - Infinity
What type of fault is indicated by the test results? -
correct answers✅Any ONE of:
● A high-resistance joint in the
protective earthing circuit.
● An open-circuit in the protective
earthing conductor.
State THREE actions that need to be taken to ensure the
electrical appliance is safe to return to service. Include
acceptable test results in the answer. - correct
answers✅● Repair faulty protective earthing conductor
circuit
, AC Theory Practice(Latest Exam 2024)
● Conduct an earth continuity test To ensure the
resistance is 1Ω or less
● Any ONE of:
● Conduct an insulation
resistance test. To ensure the insulation
resistance is 1MΩ or more.
● Conduct an earth leakage
test. To ensure that the leakage does not exceed 5 mA.
Define the term impedance as it applies to an a.c. circuit.
- correct answers✅It is the total opposition in Ω (ohms)
to the current flow in an a.c. circuit.
Impedance is comprised of three components. State TWO
of those components. - correct answers✅Any TWO of:
● Resistance (R)
● Inductive reactance (Xl)
● Capacitive reactance (XC)
In New Zealand, the standard distribution system has the
neutral conductor connected to the earth at the main
switchboard on all low voltage installations. What name is
given to this type of system? - correct
answers✅Multiple Earthed Neutral or MEN system.
State the test voltage used for carrying out an insulation
resistance test on three-phase, 400V, electrical
equipment incorporating MIMS elements. - correct
answers✅500 V d.c.
State the minimum permitted test result for the insulation
resistance test on electrical equipment without MIMS
elements - correct answers✅1MΩ
State the permitted test result for an insulation resistance
test for the electrical installation with all the permanently-
connected electrical equipment connected. - correct
answers✅0.01MΩ
State the minimum permitted test result for the insulation
resistance test on the electrical equipment incorporating
MIMS elements. - correct answers✅0.01MΩ
State ONE precaution that could be taken when using an
insulation resistance tester, set on the 500V d.c. range, to
carry out an insulation resistance test on electrical
,AC Theory Practice(Latest Exam 2024)
equipment containing semi-conductor devices. - correct
answers✅Bridge out between phase and neutral
why you would take this precaution on electrical
equipment containing semi-conductor devices. - correct
answers✅The voltage of the test instrument may
damage semi-conductor devices.
AS/NZS 3000 requires that a test voltage of 500V d.c. is
used for an insulation resistance test of a low voltage
electrical installation. State ONE reason why the voltage
is a d.c. voltage. - correct answers✅Any ONE of:
● To ensure capacitive or inductive reactance does not
influence the test
result.
● A constant maximum voltage is a more
stringent test than the momentary peaks of an a.c.
waveform.
AS/NZS 3000 requires that a test voltage of 500V d.c. is
used for an insulation resistance test of a low voltage
electrical installation. Explain why a voltage of 500V is
applied. - correct answers✅To stress the insulation at a
voltage
,AC Theory Practice(Latest Exam 2024)
above 325V a.c. (or peak a.c. voltage).
Tests have been carried out on a three-phase 400V, Class
I, plug-in electrical appliance after it has been repaired.
The test results are as follows:
Earth continuity test - out of range
Insulation resistance test - Infinity
What type of fault is indicated by the test results? -
correct answers✅Any ONE of:
● A high-resistance joint in the
protective earthing circuit.
● An open-circuit in the protective
earthing conductor.
State THREE actions that need to be taken to ensure the
electrical appliance is safe to return to service. Include
acceptable test results in the answer. - correct
answers✅● Repair faulty protective earthing conductor
circuit
, AC Theory Practice(Latest Exam 2024)
● Conduct an earth continuity test To ensure the
resistance is 1Ω or less
● Any ONE of:
● Conduct an insulation
resistance test. To ensure the insulation
resistance is 1MΩ or more.
● Conduct an earth leakage
test. To ensure that the leakage does not exceed 5 mA.
Define the term impedance as it applies to an a.c. circuit.
- correct answers✅It is the total opposition in Ω (ohms)
to the current flow in an a.c. circuit.
Impedance is comprised of three components. State TWO
of those components. - correct answers✅Any TWO of:
● Resistance (R)
● Inductive reactance (Xl)
● Capacitive reactance (XC)
