FastTrack Topic 2

Question 1

How would you change 3 phase motor rotation direction?

Answer 1

• Reversing the connection of the 2 power lines.
• 3 phase is an AC induction motor which converts electrical energy to mechanical.
• Stator remains stationary whilst the rotors rotates within it.
• 3 sets of coils within the stator.
• Alters which way the phases fire up.
• The rotor will always follow the phases as it chases the magnetic field around.

Question 2

Functional checks on the condition of a motor

Answer 2

Continuity: Is the wiring continuous?
Non Contact Test: We check for short circuit by inducing 500v should be high resistance
Insulation resistance: showing the integrity of a resistor around a conductor again inducing 500v and looking for high resistance
Any evidence of damage?
Commutation effects on DC motor?

Question 3

Hydraulic system main points

Answer 3

1: Drain, Supply and Return Legs.
2: Filters to stop metallic elements entering where they shouldn’t
3. Non return valves- ensures system stays full of oil reducing corrosion.

Question 4

Refrigeration

Answer 4

We use refrigerant as it has a lower boiling points it is needed as a gas in certain legs.

Question 5

Braby

Answer 5

Distil fresh water from sea water using auxiliary steam system as a heating medium
If fresh water from sea cant be used we use diesel
tube bundle
3 pumps
Brine air ejector uses ventulli effect to blow brine into O compensation tank