Transformers Flashcards
(33 cards)
State the clause number that outlines the requirements and restrictions for transformers
4.14 , 4.2.2.3
State the two methods used to insulate transformers one for high and low voltage
Oxide or powder
Oil or Myer film
Name two pieces of information that can be found on a nameplate
Kva rating and voltage rating
Name the two basic core types for transformers
Shell and Core
What material is commonly used to laminate the core
Staloy
According to appendix
61558 ASNZ
Name 3 applications for transformers
Distribute power
Stepping down voltage
Stepping up voltage
State the functions of the following transformers
Transmission
Distribution
Transmission - they step down the high voltage for use
Distribution - send high voltages for supply power
State the 2 different transformer windings
Primary
Secondary
What is the term used for transformers rating
Kilovolt amps
State two advantages and disadvantages for auto transfromers
Advantage - cost effective and size effective
Disadvantage - dangerous if open circuit, can’t be used to supply electrical equipment
What would be the consequence of making closing a connection where a significant voltage was indicated
Transformer will get damaged
State the condition required before connecting or disconnecting
De energised and no open circuit
State one application for each of thre following
Auto transformer - starting motors
Potential transformer - operating high voltage machines
Current transformer - operating high current machines
Which transformer can have a primary winding which is not part of the current transformer itself
Toroidal
What ratio defines the rating of a current transformer
Rated by the ratio of primary current to secondary current
State the two main factors that determine the value of induced voltage in the secondary winding of a double wound transformer
Applied voltage and number of turns
State the main principles of mutual inductions
Inducing an emf on a winding which creates magnetic flux in the secondary winding
If a double wound transformer has a turns ratio of 5 - 1
And applied voltage of 200v
And an applied current of 10 amps state the secondary voltage and current
Voltage - 200 ÷ 5 = 40v
Current - 10 × 5 = 50A
What components is placed between the windings of an isolating transformer as a safety precaution
Insulated Bar
State how to operate transformer at maximum efficiency
On full load
State a cooling method for each of the following transformers
Small low voltage transformer
Large distribution transformer
Small low voltage transformer - air
Large distribution transformer - Oil
State the losses that occur in transformers
Iron losses, copper losses
State why type of transformer loss that will occur during
Open circui
Short circuit
Open circuit - iron loss
Short circuit - copper loss
