Why is DC unsatisfactory for SM’s main distribution system?
- DC much larger and heavier
than AC machines - DC limited by commutation difficulties - Defects + Maintenance
- Battery heavy 500kg per cell and limited capacity
Name typical ESS loads
- Lighting
- Tank contents
- Anti condensation heaters
Name 115v Non Ess loads
- Sockets
- Domestic equipment
5 power sources available to V Boats
- 265v DC main battery
- Two 3MW TG’s
- One 850Kw AC DG
- One 750Kw DC DG
- AC Shore Supply
How do we protect against main types of damage ?
- Regular samples and monitoring of water conditions kept to strict limits
- Reactor protection system used that shuts down reactors if parameters hit
- Restrictions on warm up and cooldown rates
Different colours on MSC BITE monitoring system
Green - Within correct tolerance
Amber - Warming up fault that may lead to trip
Red - Out of tolerance and trip
Blue - Mode indication
Describe AC and DC parts on MG
- AC machine is on 8 pole brushless machine with incorporated PMG and exciter on the main shaft. MK204CP
- DC is a compound wound DC MG controlled by MK 84 AVFR
Briefly tabulate the process required to carry out CD
- Battery is put through a charging cycle and then discharged in a controlled manner to low state of charge
- To complete the process it is then recharged to full .
Improves condition of battery and provides capacity check
Occasions when Welding, Grinding , Burning stop
- Battery above gassing voltage 288v
- Battery temp exceeds 46
- Less than 1 hour since charge complete
- H2 content meters indicate 2%
- Loss/Reduction of airflow or equipment failure
Prerequisites for battery change alongside
- Vent system lineup check
- Battery airflow > 0.63m3/sec to 0.72m3/sec
- H contents measuring system in operation indicating <1%
- DC system clear of earths
- Electrolyte agitation system running
- Pilot cell readings taken + recorded
- Battery sump dry
- At least one CO + H2 burners running in vent state green
- Hydrogen clearance fans running
- EOOD permission
Tripping conditions for the DG DC breaker
- IPBS off / reset switch
- Breaker manual push trip switch
- Low voltage
- Overcurrent
- Reverse current
- Speed below 200rpm
Tripping conditions for AC DG BKR
- IPBS off / reset switch
- Breaker manual push to trip switch
- Low voltage
- Overcurrent
- Generator fault
- Reverse power
- DG excitation off/on switch
Explain what AC and DC diesels are
- AC gen consists of a brushless rotating field alternator at 850Kw
- DC gen is comprised of shunt wound , 8 pole self exciting type and is coupled/driven by a paxman valenta at 1200rpm
How many cables are used for SS
- DC 4 cables
- AC 8 cables
When would you connect DCSS
- When reactor is shutdown and DGs unavailable
- Long term failure of AC shore supply
Differences between AC + DC breaker
- Closing coil supply is taken directly from DC busbar and a DC+DC converter provides 50v for the retaining circuit CCCC
- Buffer amplifier monitors the FV voltage and converts it to AC output for use in overcurrent
- Centre main isolating contact is not used as the supply requires two connections
Two types of ACB
- IFR6
- IFR3
- IF6
List supplies or converted supplies onboard
- 450v 60Hz AC 3 Phase
- 265v DC
- 115v 60Hz 3 phase
- 160v DC
List 4 typical 115v Ess or non-ess loads
ESS - Lighting - Anti condensation heaters
Non- ESS - Domestic equipment
Sockets
Different types of compartment lighting
Primary Source: 115v 60Hz fluorescent lighting
Secondary Source: 265v DC Incandescent
Emergency Source: AEL
Audible alarms that need urgent attention
MFA
Fire
Flood
GWS
Methods of propulsion
- EPM controlled local at control cubicle remote at MCD
- SPM controlled locally at hydraulic manifold in engine room remote from ESP in manoeuvring
