Transformers Revision Week 3

Why are transformer windings submerged in transformer oil?

• It is a good conductor of electricity

• It is cheap and readily available

• It is environmentally friendly and easily recyclable

• Insulation and cooling

Aside from current and voltage information, what else can be found on a Transformer nameplate?

(multiple correct answers)

• %Z

  % Impedance

• Frequency

• Power Factor

• VA Rating

• Physical Dimensions in mm

All of these transformer cores are referred to as:

• Shell type

• Toroidal type

• Core type

Which of the following is a common use for transformers?

• Heating water in a kettle

• Stepping up voltage for long-distance power transmission

• Generating electricity from wind turbines

• Cooling electronic devices

How does using a silicon steel core reduce losses in transformers?

• By increasing the resistance in the core

• By decreasing the magnetic permeability of the core

• By increasing the coercivity of the core material, reducing the area enclosed by the hysteresis loop

• By decreasing the area enclosed by the hysteresis loop in the core material

How do laminations in the core of a transformer reduce eddy currents?

• By increasing the magnetic permeability of the core

• By decreasing the thickness of the core

• By providing a path of higher resistance, reducing circulating currents in the core

What are transformers rated in?

• Apparent Power (VA)

• Reactive Power (VAr)

• True Power (W)

• Doesn't matter

What is a key characteristic of an autotransformer?

• It has only one winding

• It is used exclusively in high-voltage transmission

• It is less efficient than traditional transformers

• It cannot step up or step down voltage

What safety feature do current transformers (CTs) commonly include to protect against high currents?

• Built-in fuse

• Overload relay

• Magnetic core

• Secondary shorting block

The transformer in the image adjacent has 2000 turns on its primary winding and 12000 turns on its secondary winding. The primary is connected to 11kV supply. What is the voltage output on the secondary winding?

(Answer with units and no spaces)