Oral Questions - Appliance Testing Flashcards
What is the minimum permissible insulation resistance of a sheathed heating element?
10 kΩ
If you did not have an appliance safety checker, briefly explain the tests you would carry out on an electrical appliance?
In accordance with AS/NZS 3760 Earth continuity, insulation resistance, electrical continuity.
What would excessive arcing from the brushes of a series universal motor indicate?
- Worn brushes
- Excessive load
- Winding faults
What instrument would you use to test the continuity of the on/off switch of a portable drill?
An ohmmeter
An iron is marked 1kW-240volts. What resistance would you expect between the active and neutral pins of the plug top?
Approx=60Ω R=V2/P
Why is it important to visually inspect the connections at the terminal block of an appliance?
The resistance readings will not indicate the actual integrity of the connection.
Why do appliance testers stress the earth conductor with a high current?
To test the integrity of the connections
Why does an appliance require a double pole switch?
To isolate the active conductor even if the polarity is incorrect.
Is it permissible to tie a knot in a flexible cord to hold it in position?
No
Would you accept a resistance of 1Ω as the resistance of the earth conductor in a 2m appliance lead?
No
