sec L Flashcards
(35 cards)
List 4 items fed from the main DC system
- EPM
- HSD
- DC Lube Oil
- Ballast and Priming pumping system
- Secondary lighting
- hydrogen clearance system
State the power rating of the diesels
500kw
550kw overloaded for one hour only
At what voltage does the back up AVR for the ACDG take over
if the generator terminal voltages reaches 130% of the nominal voltages, then the overvoltage protector disconnect the reverse voltage to the regulator A2
State the following trips level for DG, Lub oil pressure, overspeed, underspeed and air pressure
Lub Oil pressure :4Bar
DG Overspeed:2050 RPM
DG Underspeed 1500 RPM ( Warning at 1700)
Low air pressure : 750mBar
What is the function of battery agitation system and when is it used
To prevent stratification occurring in the battery cells.
Used;
During charges and discharges
One hour after a charge
Two hours after a top up
During a vacuum test
Explain the following
Gassing voltage and Timing point
Gassing voltage is when at 269V one cell will be starting to vent hydrogen
Timing point at 280V is where all cells are presumed to be gassing freely
Define the types of Charge
Restricted: the only charge allowed in VS green, as it does not cause gassing
Normal: more thorough than a restricted charge, 3 are carried out as part of the 17 week cycle, if time permits but minimum 2 must be carried out
Equalising: brings battery to maximum charge, 3 are carried out in 17 weeks, if time doesnt allow then 2 must be
List 8 pre-regs carried out prior to a battery charge
- Ships ventilations correctly lined up
- Battery air flow >0.5m cube
- H2 Sensors operational and less than 1%
- Battery Busbars clear of earths
- Earth leakage current under 60mA
- Battery Ag running
- Pilot cells taken and recorded
- sump dry
- one or more CO/H2 burner running if in vent state green
State the routine for carrying out a normalising or equalising charge
Ensure Pre-Reqs complete.
Carry out AC&DC Earth checks.
Charge battery at 1900A( if SG less 1200) or 1400A(if SG greater 1200) until battery reaches 269v(gassing)
reduces charge to 950A (inter rate) until battery reaches 269v again
before reducing to 325A (final rate)
continue charging to 280v(timing), record time and break charge 4.5hrs after this
Discharge battery to 246v at 100A& float the battery
Equalising :charge for 7hrs after timing point
List the occasions when you must break a battery charge
H2 reaches 2% (EOOD informed at 1.5%)
Air flow drops below normal
Electrolyte temp reaches 52 degrees (EOOD informed at 46)
Agitation fails
Earth appears on DC busbar
Any emergency situation
completion of charge
What are then naked light/ burning regulations
welding, burning, grinding and naked lights are prohibited throughout the submarine
Battery exceeds 269V
H2 content sensors indicated H2 content >1.5%
How do you correct adjust the battery SG for temp
+7 per 10 degrees above 15
-7 per 10 degrees below 15
List all the routines carried out on the battery during the 17 week cycle
1.Restricted charge
2.Normal charge
3. Equalising charge
4. Conditioning discharge
5. All round readings
6. Earth leakage current tests
7. Top ups
8. Battery clean
9. Torgue test (yearly)
Describe the procedure for a conditioning discharge.
Set planned discharge rate at 5, 10, or 20 hr rate backing off shore supply
DG is ready to run prior to battery voltages reaching 215V
at 215V volts inform EOOD
ventilation to be checked correct for charging
at final voltages for discharge rate,
FLOAT the battery
Carry out equalising charge
list 6 essential and 6 non-essential AC supplied equipment
Essential supplies; HP make up Pp, External hydraulics, Main Hydraulics, RCFW Pp, PMS, Trim Pp, Main Lub Oil Pp
Non-Essential; Extraction Pp, HP air Comps, SW Pp(F), MO heaters, Start up heaters, RO plants
list and describe the categories of SS
Primary; intended to be continuously energised, capable of supplying all ( or a specific portion if alternative is also providing power) electrical requirement
Alternative; intended to be continuously energised in addition to primary, independent of primary, and capable of supplying the remaining requirement not met by primary
Standby; Energised only if primary is lost, independent of primary, capable of meeting reactor safety load to maintain cooling
What is the minimum acceptable insulation resistance for shore supply.
10 Megohms or 2 Megohms with MEO permission
Why is dc SS provided
Provided to cope with long term losses of AC SS, supports the battery if DG are unavailable or as a DC source if battery and/ or DCDG are unavailable
State the system requirements of EPS and its principal features that it must possess
Support propulsion if;
failure of NSRP
Failure of ME
NSRP is shutdown
EPS must possess;
High availability
Operate with only DC available
Operate under Astute basic manning requirement
Explain how direction control and speed is achieved with the EPS
Direction control is via 3- position rotary switch; AHEAD/STOP/ASTERN
Speed control is done via a precision4-20mA signal to each EPSCC
Where is 115V AC Derived and name 2 pieces of equipment it supplies
115V AC is derived from 440V 3 Phase 60HZ and provide both 1 and 3phase
Its supplies
weapons
Navigation
Comms
Lighting
Show all breaker size, positions, power capacities, link configuration
+3600A - TG, Breakers(1&2), battery breakers
+3200A -DCDG,Breakers(3&4), MSC-DC (1&2),SS(1&2)
+2000A - ACDG, MSC-AC(1&2),MCPs
Which side is an MSC normally started from?
The DC side is normally the side used to start it
Where is 160V DC Derived and what is it used for?
160V is derived from PORT and STDB 440V 3Phase 60Hz via 2 TRUs associated with the rod Control gears. these are used for
CRDMs
HPDHR Initiation vs E514 &E515
