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3e051 book 1(5) Self

Self questions for volume 1(5) cdc 3e051

QuestionAnswer
What is the preferred distribution voltage in the Air Force? 7200/12470V 3 phase 4 wire Y
List three functions a substation can perform. Switch, transform, voltage regulation.
Name six major substation components. Circuit breakers, power transformers, meters, relays, lightning arresters, batteries
Which color indicates that a circuit is energized? Red (Closed)
What two main requirements must a switch in a high-voltage electrical circuit meet? Must carry it's current safey without overheating, and must have proper clearances and insulation for its rated voltage.
At least how many lightning arresters must be installed in a substation with one incoming and one outgoing circuits? 6
002 002
Which type of regulator has the primary (exciting) winding connected in shunt and the secondary (regulating) winding connected in series? Induction regulator
Which type of regulator uses taps to regulate the amount of induced voltage? Step regulator
Name one function of a potential transformer. Monitors high voltage, signal a tap changer
Which type of instrument transformer requires the secondary side to be closed at all times when the primary side is energized? Current transformer.
003 Circuit breakers 003
What suppresses the arc in an OCB? Oil.
Name the three main functions of an OCB? Quenches & cools, stretches the arc.
Explain the difference between an indoor and outdoor OCB. Indoor OCB looks like cubicle Outdoor OCB's body is designed to drain moisture.
How many different ways can an OCB operate? Three (Manual, Semi-auto, Auto)
State the purpose of the OCB timer port. For timing device connection.
004 Circuit reclosers & Sectionalizers 004
Name the three basic functions of a recloser 1. Test the line clearing the fault 2. Select device to isolate permanent fault 3. Minimize fault current time
How does a fault make the recloser trip open? Solenoid trips the recloser.
When does the sectionalizer operate? When a fault occur.
Name the main components of a sectionalizer. Contacts, spring-controlled trip, coil.
What piece of equipment must we use to back up a sectionalizer? Recloser.
005 Other high-voltage switches 005
How is an air break switch normally operated? Manually / Auto
What equipment does the air-break switch use to break the arc? Blade & stationary contacts, arc horns.
Where are air-break switches normally mounted? Substations, poles.
What allows the switches of an air-break switch to open and close at the same time? Gang operated device.
How is the arc broken by a vacuum recloser? Lack of oxygen to burn.
Which switches operate much like a vacuum switch? SF6
006 Preparing & installing high-voltage switches 006
Before installing a high-voltage switch, what data plate information must you check? Interrupting rating.
How do you position the vehicle before final placement of the high-voltage swith? So the vehicle operator can observe the placement.
What is the first connection you make in connecting the high-voltage switch into the circuit? Ground.
Why must you never let an OCB trip while the oil tank is lowered (drained)? There is no cushion for the mechanism.
007 Inspection and maintenance of high-voltage switches. 007
What do you look for when you inspect OCB's contacts? Alignment, uniform pressure.
When moisture is in oil-filled equipment, what problem occurs? Reduced di-electric strength.
What must you ensure before you "top off" oil-filled equipment? Make sure oil matches the specs.
Which items do you check visually in inspecting bushings? External parts.
On what does scheduling maintenance on reclosures depend primarily? Severity & number of reclosings occurred and di-electric strength of insulating oil.
How do you inspect contacts on vacuum breakers? Check external indicator - "wear gap"
How can you test vacuum circuit breaker to see if vacuum is adequate to interrupt current? Use Hi-pot.
What piece of equipment can aid your visual inspection of air switches? Binoculars.
State what you accomplish by repeatedly closing and opening an air-break switch? Excersizing - gets rid of corrosion.
Field experience indicates that switch interrupters with gas-filled chambers normally need recharging how often? 2.5 - 3 years.
008 Battery bank maintenance. 008
How often do you check storage batteries? Monthly.
Once you check the storage battery, what do you record? Check/record voltage, specific gravity, level of electrolyte, charging rate, internal & nearby temperatures, ventilation, and cleanliness.
What is the gravity reading of a fully charged battery cell in stationary standby service? 1200
Explain what you can and can not use as additives to storage batteries. Use only distilled water.
What instrument do we most commonly use to test a battery cell charge? Hydrometer.
What contacts can we best clean with a fine burnishing tool or crocus cloth? Silver contacts. (009)
How often do you check relay settings? Once a year, plus after any incorrect operation.
In checking contact resistance of relays, what may be indicated by a high resistance? Insufficient spring pressure.
What test voltage do you use in dielectric testing of relays that are rated under 6,000 volts? 13,000V (6,000x2 + 1000)
What is the best way to make an operational test of a relay? Operate it.
On what effect do thermostats, thermal overload, and temperature devices operate? Heating effect of electric current.
As a general rule, how often do you inspect mechanically operated substation devices? Every 6 month.
For general maintenance, what type of meter do you use? A multimeter.
010 Voltage regulator maintenance 010
What are you looking for during a visual inspection of a voltage regulator? Leaks, cracked bushings, loose connections, corrosion, and similar problems.
When you're removing a voltage regulator from service for maintenance, what's your first step in isolating it? Place the regulator in the neutral or zero position to balance the voltages on primary and secondary.
What's the maximum time between dielectric oil tests on voltage regulators? 5 years.
Created by: rpuxa
 

 



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