Transformers

According to AS/NZS 3000, where a transformer secondary winding supplies equipment via a cable that has a current rating equal to or greater than the transformer secondary winding

• A circuit-breaker must be used to protect the cable

• Circuit protection is not required for the cable

• A HRC fuse must be used to protect the cable

• Either a circuit-breaker or a fuse must be used to protect the cable

Laminated transformer cores are constructed using magnetic materials which primarily contain?

• Iron

• Copper

• Stainless steel

• Aluminium

Which two (2) of the following are the most relevant industry standards relating to transformers?

• AS/NZS 3019: Electrical installations – periodic assessment

• ISO 9001: Quality management

• AS 60076: Power transformers

• AS 2374.1.2: Minimum Energy Performance Standard requirements for distribution transformers

What is the typical output rating of a potential transformer used for monitoring high voltage

• 110V

• 24V

• 230V

• 240V

What is the safety risk if the common section of an auto-transformer winding is open circuited

• The secondary voltage could become equal to the primary voltage

• The secondary current might reach short circuit values

• Primary voltage will increase to load value

• Primaary current may equal secondary current

What is the typical rated output current of a current transformer

• 1A or 3A

• 3A or 10A

• 5A or 10A

• 1A or 5A

The secondary voltage of a transformer is produced by the principles of

• Self-induction

• Mutual induction

• Current induction

• Electrostatic induction

Which type of potential transformer is usually used for switchboard metering applications?

• Step-up transformers

• Power transformers

• Isolation transformer.

• Step down

1.      Which transformers have the highest power rating and continuous voltage performance rating of all classes of transformers?

• Power transformers (transmission and distribution)

• Current transformers (CTs)

• High-reactance (leakage) transformers.

• ELV transformers

A voltage transformer can be protected from a secondary short circuit by incorporating fuses into the secondary circuits.

• True

• False