LADWP ELECTRIC STATION OPERATOR (CIRCUIT BREAKERS, DISCONNECTS, TRANSFORMERS) PRACTICE EXAM QUESTIONS WITH CORRECT DETAILED ANSWERS | ALREADY GRADED A+RECENT VERSION

LADWP ELECTRIC STATION OPERATOR (CIRCUIT BREAKERS, DISCONNECTS, TRANSFORMERS) PRACTICE EXAM QUESTIONS WITH CORRECT DETAILED ANSWERS | ALREADY GRADED A+RECENT VERSION 1) Arc - answer The current that continues to flow across the opening contacts of a switch (or across any opening in a circuit) is known as an __________. 2) dielectric - answer Dry, clean air normally has a __________ strength of about 10,000 volts per inch. This means that you would have to apply a voltage greater than 10,000 volts across conductors separated by one inch of air to establish current flow across the separated conductors. 3) resistance - answer Air has a high __________ value so this current flow creates heat. 4) cool - answer Using multiple contacts and rapid opening times helps __________ the arc by reducing the cross sectional area of the arc or by lengthening it. 5) zero - answer Alternating current is easier to interrupt than direct current because periodically (120 times per second in a 60Hz circuit) the current value in the circuit becomes _________. 6) safe - answer Visual disconnection is usually necessary to create __________ working conditions for repair and maintenance crews. 7) series - answer In station designs, circuits are placed in __________ with disconnects. 8) Transformers - answer __________ allow the transfer of electric energy between two circuits that are completely insulated from each other through the use of magnetic induction. 9) induced - answer Back emf or counter emf is also referred to as __________ voltage. 10) magnetic - answer Much stronger __________ fields are obtained if the wire is wound into a coil with many turns of wire. 11) spiral - answer A ___________-shaped coil allows a much stronger field to be created than a flat coil does. 12) self induction - answer When current flow in a coil causes an emf to be induced in itself, it is known as __________. 13) mutual - answer If a second coil is placed in the field of the first coil that is connected to an AC source, the rising and collapsing magnetic field of the first coil will cut across the second coil and will induce an AC voltage in the second coil as well. This is known as __________ induction. 14) inductively - answer When there is no physical or electrical connection between the two coils yet energy is transferred from one coil to the other. The coils are said to be __________ coupled. 15) windings - answer A simple power transformer essentially consists of two 16) Permeability - answer a measure of the ability of a substance to conduct magnetic lines of force. 17) Silicon - answer __________ steel, which has a high permeability rating, is used as a material for manufacturing transformer cores. 18) 98 - answer Well-designed transformers are about _____% efficient. 19) excitation - answer Since they have no moving parts, the only losses are those caused by field __________ when a transformer is energized, and resistance of the core material. 20) Eddy - answer Circulating currents, called __________ currents, cause unwanted heating of the transformer and a loss of energy. 21) silicon - answer By laminating it, using thin sheet of __________ steel or other ferrous alloys sprayed with an insulating material, eddy currents are greatly reduced in transformers cores. 22) Hysteresis - answer The heat and accompanying loss of energy caused by friction of the molecules is called __________. 23) iron - answer The losses of electrical energy that appear as heat and which are cause by hysteresis and eddy currents in the magnetic core are known as __________ losses. 24) switchgear - answer electric equipment that provides a means of centeralizing switch and circuit interupting devices. 25) 3 major parts of CB contacts. - answer contacts, operating mechanism, and control circuits. 26) operating orders-2 - answer clearance needed when encroaching on approach distance. 27) 4.8kv - answer 25" 28) 34.5kv - answer 28" 29) is clearance required when tanks are dropped - answer yes 30) pneumatic uses a? - answer reciever 31) hydraulic mechanism uses? - answer accumilator 32) Operating orders-44 - answer safe handling of SF6 33) should you move bushings under pressure? - answer no 34) classifications of CB's - answer air, oil, gas, and vaccum 35) CB's are capable of breaking currents under? - answer normal and abnormal conditions. 36) current zero - answer used on CB's to extinguish the arc. 37) two common contacts - answer main, and arcing 38) Dielectric strength - answer is a measure of how well a medium can, withstand voltage without conducting electricity. 39) pressure on a medium_____________dielectric strength. - answer increases 40) On vacuum CB, the arc chutes are removed cleaned and inspected for physical damage. - answer False 41) Rubber gloves can be used without leather gloves. - answer False 42) Before working on a CB, always make sure that the CB is? - answer tagged, locked out, and grounds are hung 43) Before testing a CB for power always check your tester against a known source of voltage. - answer hot dead hot 44) most CB's have? - answer Pumps, valves, compressors 45) Which is not classified as a CB - answer hydrolic 46) SF6 - answer Sulfur hexaflouride 47) most important "tool" is? - answer equipment manual 48) contact resistance test; uses a_________________to measure CB contact resistance. - answer ductor micrometer 49) 4 types of CB mechanisms - answer air, hydrolic, spring, and solenoid 50) the term "operation" includes? - answer tripping, closing, and reclosing 51) when CB mechanisms are on "latch" you need air, electrical, or hydraulic energy to make the mechanism operate. - answer false 52) circuit breakers are classified according to their? - answer dielectric medium 53) circuit interruption must occur whether the tripping or opening signal is received with the circuit breaker fully closed or in any partially closed position. - answer true 54) in both pneumatic and hydraulic operating mechanisms, the opening spring is charged as the breaker contacts close. - answer true 55) the purpose of compressed gas in a pneumatic circuit breaker is to drive what? - answer the hydraulic fluid into the operating piston of the main mechanism.