Attach Cords equipment to connect 230 V single phase Flashcards
What is the voltage and frequency of single phase power generation in Australia
230 V
50 Hz (Pass through +ve and -ve cycle 50 times each sec )
What is the equivalent d.c value of a.c .
70.7% of the peak a.c value
What is the basic arrangement of an electrical circuit ?
What are the names of the following protection device symbols ?
Fuse
Circuit breaker
List the name, operating principle and advantages of the following protection devices.
List the name, operating principle and advantages of the following protection devices.
How does Residual Current Devices (RCDs) work ?
RCD detect an imbalance in the active and neutral currents in a circuit.
An imbalance occurs when ‘leakage’ current flows in the protective earthing conductor, causing the active and neutral currents to be unequal.
The RCD detects the unbalanced currents and ‘trips’ to switch off the current in the circuit.
How do resistance testers work ?
Ohmmeter leads connected across component
Ohmmeter apply small voltage across component and read current
Resistance is calculated and displayed.
What equipment is this and how does it work ?
An insulation resistance tester applies a d.c. voltage (250 V, 500 V or 1 kV) across two conductors that are insulated from one another.
Low resistance reading = insulation cannot contain or hold the test voltage
High reading (MΩ) = insulation is in good working order.
What is Parallax Error ?
live and earthed parts of an electrical installation, or parts thereof, including consumers mains and submains shall be not less than _____ ?
1 M Ohm
When testing insulation resistance, the rule of thumb is to select a test voltage that is at least _______ ?
Double the normal operating voltage that the insulation will be exposed to.
Label the pins.
What does the test result indicate ?
What does the test result indicate ?
Fill in the blanks
Fill in the blanks
List the colour code
What is International Protection (IP rating) ?
Rating system classifies enclosed equipment based on the degree of protection provided against the ingress of solid objects (e.g. dust) and water.
dust = 0 to 6
water = 0 to 8
What are the main functions of earthing system ?
Ensures stability of the supply voltage.
Ensures that protection devices function correctly.
Eliminates the chance of hazardous voltages appearing between exposed conductive parts.
What is the meaning of this symbol ?
Class II Equipment
Double insulated
Define the following types of insulation
- Sup = in case basic fails
- Doub = to create redundancy
What is a short circuit ?
Why is 250 V used for insulation testing on equipment containing surge protection device.
High voltage can cause a low resistance from active to earth via the surge protection device
State the min insulation resistance btw live and earth conductive parts for the ff:
Class I appliances:
Class II appliances:
Appliances containing mineral insulated metal sheath heating elements:
1 MΩ
1 MΩ
0.01 MΩ
It is essential that insulation resistance testing is only carried out on equipment that is _____.
disconnected from the supply
