SBO Electrical Flashcards
(29 cards)
What powers the SBO during normal conditions?
Bus 11 from high side of Bus 16
What feeds the U2 125vdc Alt Battery?
MCC 65-1 under normal conditions. IF LINED UP TO U2, MCC 29-2 will feed MCC 65-1 (safety related bus feeding MCC 65-1)
All loads will shed from MCC65-1 prior to setting this lineup
What happens to the SBO on a loss of 138kV Bus 3 or TR 12?
What actions must be taken upon this condition?
SBO will lose power.
Power must be restored to SBO within one hour of loss of power or else SBO must be declared NON-FUNCTIONAL due to loss of battery charger
What is the purpose of the crosstie between Bus 61 and 71?
for maintenance purposes or loss of Bus 11 ONLY.
Not to cross tie busses under ACCIDENT condition
What causes a trip of the a trip of the breakers from Bus 11 to 61/71?
How are they reset?
Trip on Bus 11 undervoltage.
Must be manually reset
How are the Bus 61/71 4kv breakers field indication of proper operation?
2 white lights indicate continuity through trip and close fuese
What power sources are available to the SBO?
AC during normal operation - Bus 61
DC - each SBO has dedicated 125vdc system to provide electrical power to for startup and operation, 4kv breaker operation, SBO lube oil circ pump operation during event, and various functions
What is the deisng basis of the SBO 125vdc batter?
they can do their design function for 1 hour following a loss of battery charger. Therefore, after one hour without a charger, the batteries must be considered not available for SBO system and system declared INOP
What consists of the SBO DC systems?
125vdc batter 6A (7A)
Normal battery charger powered from 65-1/75-1
125vdc switchboard 6A(7A and distribution panel 6A-1(7A-1)
What is the purpose of the maintenance charger and it’s power supply?
Located on U3 side and powered from 75-1. available to supply power source to U2 or 3 SBO battery though a maintenance switch
What interlock exists for the SBO DC Maintenance charger?
Interlock so that it can supply the SBO battery for U2 or U3, but not both simultaneously.
How is the SBO UPS configured?
Normal power from 125 vdc dist panel via inverter
If inverter fail or loss of 125vdc dist panel, the static switch (normal seek w/ 30 sec. TD) will transfer over to MCC 65-1 via isolimiter
What provides normal power to SBO UPS?
125vdc dist panel via inverter 6B (7B) and manual bypass switch
What happens on an SBO UPS INverter failure?
On an internal fault, the static switch would automatically swap to align the UPS dist panel to MCC via specially metered transformer called an isolimeter
What is the SBO UPS Static Switch?
Auto transfers to supply manual bypass switch from either 125vdc or isolimeter.
Auto transfers back to inverter 30 sec after inverter conditions return to normal, provided auto retransfer logic toggle switch is in ON position.
How can the SBO UPS be transferred to the Isolimeter?
Automatically or Manually via Manual Bypass Switch
What is the purpose of the SBO Isolimiter?
Rectified AC powered from MCC 65-1 (75-1) and is alternate feed to SBO UPS
What condition is the SBO in when MCC/Isolimeter is powering the SBO UPS?
Must be declared INOP
How does the Airstart tran swap and overcrank logic work for the SBO?
The selector Switch chooses which bank to start on
Starts and attempts to roll the engine. If it doesn’t reach 80 rpm in 4 seconds, it will attempt using the other train.
If engine fails to reach 200rpm in 10 seconds of start signal, OVERCRANK lockout will prevent future starts until reset.
What happens at 450rpm during SBO Startup?
At 450 rpm, DG will pause momentarily while bearing oil pressure is below 20# until it reaches 20# in BOTH engines, then rolls DIRECTLY to 900rpm
Which Engine trips are NOT bypassed?
Overspeed,
Generator Ground
Generator Differential
What stops SBO from going over 450rpm with oil <20#?
PLC
What happens on a PLC or DCS Failure?
Complications with startup but not prevented. PLC taken to bypass w/local switch
Which PLC bypassed what is the only allowed way to start the SBO?
Local Emergency Start
