WorksheetsGeneration/Transmssion Distribution Revision
Total questions: 20
Worksheet time: 11mins
How is the maximum number of PV panels on a string determined?
By the maximum input voltage of the inverter
By the number of solar cells in each panel
By the amount of sunlight available
By the voltage of the solar panels
What is the typical voltage output from a SOLAR FARM inverter?
120v single phase
230v single phase
400v three phase
1000v three phase
One method of generating uses the natural power of water flowing from lakes or mountains down to the sea to drive generators.
Which is the type of generator typically used in New Zealand for this?
Induction generator
Synchronous generator
Pemanent magnet generator
DC generator
Generated values of voltage are typically 11kV but could be as high as what value in New Zealand?
33kv
110kv
220kv
350kv
Which range of transmission voltage levels is typically used in New Zealand?
110 - 220kv
220 - 765kv
765 - 1100kv
1100 - 1500kv
What is the main disadvantage of the very high transmission voltage levels?
Decreased power transfer capacity
The cost of transformers, switchgear, and other equipment increases as the voltage increases
Decreased efficiency
Increased voltage drop
What is the main advantages of the 3 phase 4 wire system as used in New Zealand?
The system is safer than a 3-wire system
The system is more powerful than a 3-wire system
The system is less expensive than a 3-wire system
We are able to obtain both a 3 phase and a 1 phase supply
What is the typical high voltage distribution voltage level used in New Zealand?
110KV – 220KV
230V – 400V
6.6 - 11 kV
50V – 1000V
Using much higher transmission voltage levels gives improvements in several areas.
Which two (2) of these improvements are correct?
Reduced losses
Reduced cost of equipment
Increased systems stability
Lower volt drop
For the national supply grid generation, transmission and high voltage distribution, which of these describes why multiphase power is used in New Zealand?
There are fewer conductors required for transmission.
Three phase and single phase supplies are available.
It is more efficient to generate multiphase power.
Multiphase alternators can be run in series.
In regards to the national supply grid generation, transmission, and high voltage distribution, which two [2] of these describe a star connection within a transformer’s windings?
All 3 phases are connected in a closed loop system
Motors achieve a very high speed and torque.
Line current is equal to phase current.
Line and phase voltages are different.
Phase voltage = line voltage.
In regards to the national supply grid generation, transmission and high voltage distribution, which two [2] of these describe a delta connection within a transformer’s windings?
Line voltage is measured between phase and neutral.
No neutral point.
Line and phase voltages are different.
Phase voltage = line voltage.
Two different voltages are available from the same system.
Electricity is normally generated in 3 phase AC because?
More poles can be physically fitted to a 3 phase alternator thus allowing for a lower speed
3 phase alternators are simpler construction than a 1 phase alternator
Alternators are physically smaller than the equivalent power rated 1 phase alternator
3 phase alternators have higher output voltages as required for transmission
What desription best describes how a transformer is connected in a star configuration
the end of each winding is connected to a common point
the three windings are connected end to end forming a closed loop
the start of each winding is connected to a common point and the ends are connected to form a closed loop
For the same line voltage, a star connected alternator requires less insulation than a delta connected alternator.
True
False
Transmission voltages of between 110 - 220kv are used to reduce transmission line ______ ( Select 3 options)
current
size
losses
impedance
The transmission current is 10 amps and the transmision line resistance is 10 ohms. What is the total power loss in the line?
0.1 kw
1 kw
10 kw
100w
A factory 50 km from a generating station requires 1000kw. The transmission voltage is 11000v. What is the current drawn?
9.9A
90.9A
999A
9999A
The transmission current is 90 amps and the transmision line resistance is 25 ohms. What is the total power loss in the line?
2.025 Kw
20.25 Kw
202.5 KW
2025 Kw
A factory 50 km from a generating station requires 750 Kva. The transmission voltage is 22000v. What is the current drawn?
34.09A
340.90A
29.33A
2.93A
