FAQ Orals (Generator)

What Is Load Sharing?
Load Sharing Is The Equal Balance Of Loads Between Running Generators Irrespective Of Load Changes.

What Is Sequential Starting?
Sequential Starting Is The Automatic Starting Of Essential Equipment When Power Is Returned After A Total Power Failure,  I.e. Equipment Such As Steering Gear, L.O Pump, Sea Water Pump Etc.
 
What Is The Purpose Of The Under Voltage Trip?
An Under Voltage Trip Is Fitted To All Generator Breakers.  Its Main Function Is To Trip The Breaker When Severe Voltage Dip (around 50%) Occurs.  The Under Voltage Trip On A Generator Circuit Breaker Also Prevents It Being Closed When The Generator Voltage Is Very Low Or Absent.
  
Describe How Synchronising Lamps Are Used To Parallel A Generator.
This Is Normally Used As A Back-up Or Alternative Way To The Synchroscope, The Lamps Are Connected Between The Incoming Generator And The Bus-bars.  The "Sequence Method" Is The Preferred One As It Displays A Rotation Of Lamp Brightness, Which Indicates, Whether The Incoming Machine Is Running Fast (clockwise) Or Slow (anti Clockwise).  As With The Synchroscope, The Lamp Sequence Must Appear To Rotate Slowly Clockwise.  Correct Synchronisation Occurs When The Top Or "Key" Lamp Is Dark And The Two Bottom Lamps Are Equally Bright.
 
Name The Trips Found On A Generator Circuit Breaker.
Over Current
Under Voltage
Reverse Power.
 
 
Draw And Explain How Earth Lamps Works.
A Direct Earth On One Pole Will Short Circuit It's Lamp, Causing The Other Two To Shine Brightly.
 
Explain What Would Happen If You Were To Lose A Generator.
First The Standby Generator Set Would Start Up And Automatically Put Itself On The Board.  If This Did Not Happen, The Ship Would "Black Out" And After A Time Delay, Usually 30 Seconds, The Emergency Generator Would Start Up And Supply The Emergency Switchboard, Which Supplies Essential Equipment.
 
 
What Is Reverse Power Protection For?
Generators Intended To Operate In Parallel Must Have A Reverse Power Protection Trip.  A Reverse Power Relay Monitors The Direction Of Power Flowing Between The Generator And The Switchboard.
If A Prime Mover Failure Occurred The Generator Would Act As A Motor.  The Reverse Power Relay Detects This Fault And Acts To Trip The Generator Circuit Breaker.
 
What Is The Function Of The A V R?
The Function Of The A V R Is To Regulate The Exciter Field Current Automatically, Comparing The Generator Terminal Voltage With The Standard Set Voltage And Thus Maintaining The Generator Terminal Voltage To A Constant Value, Regardless Of Load Changes.
What Conditions Are Necessary To Parallel Two Generators?
I) The Speed Of Both Machines Must Be The Same I.e. The Frequency
Ii)The Voltages Must Be The Same
Ii)They Should Be In Phase.
 
What Is The Purpose Of The Over Current Protection Trip?
The Purpose Of The Over Current Protection Is To Trip The Generator In Overload Situations.  The Trip Is Usually Set At 150% Operating Capacity And Has A Time Delay Of Usually 20 Seconds.  This Allows For Short Periods Of Overload Currents.  It Also Protects Against A Short Circuit In The Generator.  

What Loads Are Considered Non-essential?
Loads Considered As Non-essential Are: Air Conditioning And Ventilation, Laundry, Galley, Refrigeration And Deck Equipment.