Outside 3rd year

Pataasin ang iyong marka sa homework at exams ngayon gamit ang Quizwiz!

A closed transformer bank supplies 240-volt, 3-phase and 120/240-volt, single-phase power. With a single-phase load of 30 kVA and a 3-phase load of 60 kVA, the total load on each of the power pots is ?

30 kVA

A transformer rated at 75 kVA can carry ___ at 240 volts

312.5 A

Benefits provided to employees average ___ of their non-overtime wages.

35%

A 150-kVA transformer bank consists of three 50-kVA transformers connected in a delta-delta configuration. The primary nameplate voltage rating is 2,400/4,160 volts. With a balanced full load, each of the primary leads will carry ? .

36 A

A 300-kVA transformer bank with the secondary windings configured in wye feeds a balanced 480-volt load. At full load, or 100% of the power rating, the current through each of the secondary load lines is ?

361 A

A tower saddle is fastened with ? hooks and tightened by wing nuts.

4

After determining which transformer is bad in a 3-phase bank, there are ___things to check for on the nameplate before calling for a new transformer.

4

Current transformers for metering can be designed or shaped as any of ? types.

4

In order to move one phase to the new location on a vertical, 3-phase, deadend pole, it takes ____ set(s) of rope blocks.

4

There are ___ pieces of equipment used in a substation to adjust the voltage.

4

There are___ attributes that a positive effect on employment potential

4

On each conductor, subconductor, or pulling line, 3-phase grounds are placed at increments of no more than ? .

4 miles

Saddles should be equipped with _____extensions to prevent wire tongs from interfering with each other if the saddles are used on the same side of the pole and near each other.

4"

If two 25-kVA transformers are connected into an open wye-open delta bank, the total bank capacity would be

43.5 kVA

A 7,200-volt line has a drop of 90 volts between the source and end line customer. To deliver the same amount of power to the customer at 14,400 volts, the voltage drop would be ? .

45 V

The current flow in a wye circuit is about ___ less than in an equivalent delta circuit.

58%

The voltage across a wye connected transformer coil is ? of the line-to-line voltage on the wye system.

58%

One procedure to find a bad transformer in a 3-phase bank is to isolate and test each individual transformer. This involves ____ steps.

6

There are ___ items that makeup a typical PV system

6

A closed wye-delta transformer bank supplies 240-volt, 3-phase and 120/240-volt, single-phase power. With a single-phase load of 45 kVA and a 3-phase load of 90 kVA, the total load on the lighter transformer is ? .

60 kVA

A 450-kVAR capacitor bank is installed on a 4,160-volt wye line. The phase to ground voltage is 2.4 kilovolts. The capacitors draw a continuous current of __?

62.5

A wye-wye bank is built with three 75-kVA transformers. The voltage on the secondary mains is 208 volts from line-to-line. When operating at balanced full load, or 100% of the power rating, the current through each secondary leads is ?

625 A

When a capacitor charges and discharges during each time constant, the voltage will change by ? of the amount left to reach the fully-charged state.

63.2%

A three-transformer bank serves a mixed single- and 3-phase load at 120/240 volts. The clip-on ampere meter readings on the secondary are:A phase = 195 AB phase = 175 AC phase = 105 AThe total kVA bank load is ? . (Round the FINAL answer to one decimal place.)

65.7 kVA

There are ___ steps that are common to the installation of all substation equipment.

7

A(n) ___ fuse would normally be used to protect a 50-kVA transformer connected to a 14.4-kilvolt line. (Round the answer to the nearest whole number.)

7 A

Transformers installed on a 12.5-kilovolt, 4-wire circuit must have a nameplate primary voltage rating of ? when the primary is banked in a wye.

7,200/14,470Y V

A single-phase tap take off from a 12.47-kilovolt, 3-phase wye line has a line-to-neutral voltage of ___?

7.2 kV

By stringing a fourth wire and reconnecting the substation transformer secondaries from delta to wye, the capacity of the circuit can be increased by ? .

73%

An open wye-open delta bank with equally sized transformers has a kVA rating of ___ of the combined transformer power ratings.

86.6%

A 75-kVA closed wye-delta transformer bank feeds a 3-wire, 480-volt load. When operating at full rated capacity, the current on each of the three load lines is ? .

90 A

The polarity of the primary and secondary terminals of the instrument transformers is normally marked with ? .

A large dot

To parallel the secondary windings of transformers with three secondary terminals, the ? coil leads are paired and connected to the terminal studs inside the tank.

AC and BD

If a typical single-phase transformer with three secondary terminals delivers 120/240 volts to a residential customer, the internal ? coil leads are connected to the X2 terminal.

BC

Which item listed below would not be considered a characteristic of professionalism?

Being on time to the job 90% of the time

When changing out the three sets of insulators on a 3-phase running corner, the first conductor disengaged from the insulators and moved into the clear is the ____.

Bottom phase

A current carrying line, when located inside the substation yard, is called a ____?

Bus

Wind power varies directly with the ___ of the wind speed

Cube

Vertical axis turbines such as the egg beater type are also called ___ wind rotors

Darrieus

Decreasing the amount of inductance in a circuit will cause inductive reactance to__?

Decrease

A converter is not one of the types of substations that are downstream from a generating station

False

A crew's job Should always be limited to what the Foreman can personally supervise

False

A no-load tap changer requires the load on the transformer to be reduced while the tap change is made.

False

A protective apron is not required when working with nickel-cadmium substation batteries.

False

A substation with a no-load tap changer transformer makes automatic adjustments to the voltage as needed during the day.

False

A type D recloser rated at 14.4 kilovolts can be used at any voltage up to that rating.

False

All three sets of insulators on a 3-phase running corner cannot be changed out with only two sets of rope blocks.

False

Because it is so dependable, wind power is calculated as part of the energy reserve

False

Capacitors used in substations do not help adjust the voltage

False

Dangerous light from fiber -optic cables is bright and easily visible

False

For an operator's safety, a solid copper wire grounds the swing-handle used to operate a switch in a substation yard.

False

In a 3-phase system, the three voltages are of different magnitudes

False

In a cable trench, each wire in the cable is identified with a tag and each cable is identified with an ID code.

False

In a wye banked secondary circuit, the star point leads from the X bushings of the outboard transformers carry only the load imbalance and may be of reduced size.

False

In every case, it is safer to ground using an equipotential zone than to perform live-line work on a circuit.

False

In order to parallel the coils on a transformer with four secondary bushings, it is necessary to remove the lid.

False

In substation metering, a VT and a PT are two different types of instrument transformers.

False

Insulated link sticks must be used between the rope blocks and the wire grip on all voltages.

False

Knowing how interoffice politics work within a employer's organization is the only positive attribute Qualified Electrical Workers must develop to keep their jobs

False

Looped ends are no longer required on tie wires because of the advances in live-line tools and techniques.

False

One method of checking an underground system is to use a smaller fuse so the cable is not subjected to the full fault current generated by the fault.

False

The coil on type H or type L reclosers is fixed by the manufacturer and cannot be changed out.

False

The current drawn by a capacitor is dependent on the load current on the line.

False

The definition of the term fuse-coordination means that only fused disconnects are coordinated.

False

The metal mat that is installed at the base of a manually controlled air-break switch forms a perfect equipotential zone and offers 100% protection should the switch mechanism become energized during operation.

False

The most common result of short circuits on overhead lines is that the conductors will fuse together.

False

The only reason to keep the excess tie wire cut off when untying a conductor is to keep the rotary prong tool uncluttered.

False

The temperature of equipment in a substation is monitored by gauges only and not by relays.

False

There are three different voltages available in a wye connected system

False

When the 120/240-volt secondary windings of a transformer are connected for series operation, the secondary vectors are connected head to head or tail to tail.

False

If an underground containment oil tank is used as part of an SPCC plan at a substation, it can be made out of concrete or ____ .

Fiberglass

Premises cables must be rated for ____ to meet codes

Fire retardance

On distribution lines, capacitors are often switched out of service several times during the day to prevent damaging ____from occurring.

High Voltages

Frequency is measured in hertz, which is represented by the symbol ?

Hz

The formula to calculate an individual transformer load in kVA is

I X E / 1000

The inductance of a coil will ___ if the turns of wire in the coil are wound closer together.

Increase

Nitrogen gas is often used in substation transformers to create an ___ layer above the oil.

Inert gas

The electrical industry demands a willingness to commit one's self to__?

Lifetime of learning

A career in electrical construction industry offers___?

Limitless growth potential

DC power used to operate switchgear in a substation is an example of a ? load.

Momentary

Capacitors are installed on distribution lines to balance the inductive reactance caused by a customer's ____ load.

Motor

A battery room ventilation system is an example of a ___ load that the batteries must be able to support in case of an outage.

Non-continuous

Transformers with secondary voltage ratings of 120/240 volts can be used to supply a 120/208-volt load when the secondary coils are connected in ? and ? banked.

Parallel / wye

Journeyman Qualified electrical workers should always strive to set a good example and maintain the highest level of ____

Performance expectations

The voltage measured across a single winding or phase is known as the ___ voltage.

Phase

A good place to look to find the names of and information about the electrical contractors operating in a specific area is the

Phone book

Most building management systems use ___ cabling

Proprietary copper

One of the most important duties of a Foreman is ____

Record-Keeping

Three personal characteristics formulated during the apprenticeship are commitment, an educational foundation, and ____?.

Responsibility

Salting provides several advantages to an organizing effort. Which item listed below would not be considered an advantage?

Rules, Laws, and regulations that are being followed are exposed

Capacitors installed on distribution circuits are often referred to as ? capacitors.

Shunt

Structured cabling installed to TIA-568 standards uses a ___ cabling architecture

Star

The common connection point on a 3-phase wye connected bank is also called the

Star point

A bundled conductor reduces the higher impedance to current flow caused by skin effect

True

An ampacity chart is not very useful in determining conductor size for a utility circuit.

True

By placing the secondary 120/240-volt coils in parallel, the full kVA of the transformer is available at 120 volts.

True

Capacitors installed on a distribution system will affect the power factor on the transmission system back to the generator.

True

In new substations of 500 kilovolts, individual single-phase transformers are used because 3-phase transformers at these voltages are extremely large and expensive.

True

Increasing the frequency will cause inductive reactance to increase.

True

Only transformers with two primary bushings can be installed on a primary delta system

True

The five historical grounding methods discussed all place the worker in a parallel fault current path.

True

Through collective involvement, the future of electrical industry shall have no limits. Without individual, personal involvement, there will be no future to worry about

True

When changing out a line angle crossarm, enough pressure is put on the strain link stick to take the angle out of the insulator.

True

When replacing an insulator with live-line tools, the tie wire is first untied and cut away on the side where the tong will be installed.

True

When using the leaning method, if the damaged pole is too far away for the Qualified Electrical Worker on the new pole to untie the conductors, the pole can be moved closer.

True

The countermeasure part of a substation SPCC plan must be ____ to/for each facility.

Unique

Identification of and communication with the ___ are crucial to the success of any organizing campaign.

Unorganized electrician

A high-voltage DC circuit breaker uses ___ as an interrupting medium.

Vacuum

To connect the secondary coils for series operation on a transformer with four secondary terminals, the ? terminals are joined with an external jumper.

X2 and X3

The symbol for capacitive reactance is

Xc

If 20 volts AC were connected to a coil, it would result in ___ current than 20 volts DC connected to the same coil.

a smaller

Maximum voltage is being generated when a loop of wire is moving ____to the lines of flux.

at right angles

If the tap-changing mechanism of a voltage regulator is stuck on a tap, raise and lower the voltage using the ___ switch and then return the switch to automatic to see if the tap changer will move on its own.

auto-manual

An example of equipment used for isolation protection is ? .

barrier fencing

A power transformer oil sample should be taken from the ___ tank

bottom of the

Of the several types of ineffective grounding methods historically used, ? grounding is the most dangerous method still in use.

bracket

One method of calculating the average value for an AC sine wave is by___ ?

calculating the average of all the instantaneous values in half a cycle

Clamp top insulators found on transmission lines are the cotter key locking type and the ? locking type.

clamp bolt

If operating properly, a switch that uses sulfur hexafluoride "bottles" operates ___? .

de-energized and arc free

The spreader bar is allowed to make contact with the striker arm when replacing timbers using a helicopter in order to ? .

discharge the electrical charge

The development of personal pride requires ____ and dedication.

effort

When performing a live-line timber change near energized power lines, the pilot must disarm the ? .

electrically-operated quick release

The voltage across a transformer winding in a delta system is ___?

equal to the voltage from line-to-line

When using the auxiliary arm lift method, the arm should be positioned immediately below the conductor to check for the proper spacing of wire holders and ___ prior to engaging the conductors.

extension of the lifting tong

To protect a distribution system from an internally shorted capacitor, a ___ is used to clear the faulted unit from the circuit.

fused cutout

A unit of inductance is called a(n) ? .

henry

A typical distribution transformer provides 120/240 volts to residential customers and has its coils connected ? .

in series

If the number of turns of wire in a coil is decreased, the___ ?

inductance of the coil will decrease

The installation used to measure an underground primary service is a specially designed cabinet with dead-front primary connections on one side and ? on the other side.

instrument transformers

A qualified electrical worker should become politically active when he or she ___ and that activism should continue throughout his or her career

is an Apprentice

The voltage at the earth's connection point ____ when compared with that of the overhead conductor it is attached to.

is nearly the same

When current flows through a capacitive load,___?

it will be out of phase with and lead the voltage

In a conductor, greater __ resistance

length increases

When replacing an insulator with live-line tools, if the tie wires are in bad condition, ____should be applied to the conductor before untying the phase.

lifting tongs and holding tongs

The secondary windings of three substation transformers are banked in a delta. The potential across the windings is 2,400 volts. The output voltage from ? is ? .

line-to-line/ 2,400 V

A disconnecting or isolating switch is designed to open or close when ___ current is broken or flowing.

negligible

Transformers with secondary voltage ratings of 120/240 volts are banked to supply 3-phase 208-volt power on a 4-wire service line. The secondary coils must be connected in __ banks.

parallel and wye

For years, grounding was a controversial subject, and in the future it will continue to be a controversial subject. A primary reason for this is that ?

people resist change

An outdated grounding approach, the ___ method requires three ground cables with length enough to reach from the line conductors to ground.

phase-to-common-ground

Of the historically used grounding methods, the one offering the most rapid fault clearing by the system's overcurrent protection equipment was provided by the __method.

phase-to-phase-to-ground

The use of equipotential grounding will ? .

provide a low-resistance path to shunt fault current around the worker

Distribution capacitor banks in a substation are normally surrounded by a fence with danger signs and are ____?

set up on insulators

If the ___ of a capacitor is increased, the strength of the capacitor will be greater.

surface area of the plates

Link sticks are made in three different types: strain, roller, and ?

suspension

The unique quality about obtaining educational training is

that it cannot be taken away

The "great myth" concerning grounding is that a connection to ?

the earth always gives a V = 0 condition

By doubling the voltage of a line, ___?

the same load can be supplied at four times the distance

Only one CT is used to meter a 120/240-volt 3-wire service because both 120-volt conductors go through the CT in opposite directions.

true

If during periods of light loading, excessive amounts of capacitive reactance is added to a circuit, the___?

voltage could rise to an intolerable level

A transformer has 7,200 volts across the primary and 480 volts across the secondary, and 10.5 amperes are flowing through the primary. The secondary current is ?

157.5 A

If a sine wave has a peak value of 240 volts, the RMS value is

169.68

A 100-kVA transformer of a 300-kVA wye-delta bank has failed. Power has been restored by converting the system to open wye-open delta. The power rating of the open bank has been reduced to

173 kva

The two bridle ropes used with a spreader bar in helicopter work should be 5/8 inch by ? double-braided.

18'

Wye-wye and delta-delta transformer banks can have either a 0° or ? angular displacement.

180*

prior to ___ , all " A" members received pension benefits even if they were employed by contractors who did not contribute to the plan

1957

When using the side method to replace a crossarm, it takes ____ set(s) of rope blocks to do the job.

2

The OSHA 1910.269 law defines grounding equipment minimum current ratings. The standard requires that grounding equipment shall be capable of conducting maximum fault current that could flow at the point of grounding for the time necessary to clear the fault. This equipment shall have an ampacity greater than or equal to that of ? copper.

2 AWG

When working in the vicinity of insulated overhead ground wires, the specified minimum approach distance of ? for a 15-kilovolt circuit must be maintained.

2' 2"

Transformers installed on a 4.16-kilovolt, 4-wire wye system can have primary voltage ratings of 4,160 volts or

2,400 v

If the voltage at the earth's connection point is 20 kilovolts, the surface voltage measured at a distance of nine feet away is ? .

2.5 KV

When installed, the right hand bushings of an OCB are numbered ? , ? , and ? .

2/4/6

A closed wye-delta transformer bank supplies 240-volt, 3-phase power and 120/240-volt, single-phase power on a 4-wire service line. If the single-phase load is 36 kVA, the transformer with the grounded X2 bushing will supply ___ of that load.

24 kVA

A wye system with a line-to-neutral potential of 14,400 volts has line-to-line potential of___?

24,940 V

If B phase is lagging A phase by 120°, C phase will lag A phase by ___ ?

240°

A 225-kVA delta-wye transformer bank feeds a 480-volt secondary circuit. The secondary windings draw 271 amperes at full load. The current through each of the two X terminal to star point conductors is

271 A

To supply 480-volt, 3-phase power with the transformer secondary coils banked in a wye configuration, the transformer secondary voltage ratings must be ?

277 V

There are __ advantage of distributed generation model

3

There are ___ steps that should be followed when training an apprentice

3

There are ____ course of action Qualified Electrical workers can take to help eliminate the possibility of economic hardship during periods of unemployment

3

There is/are ___ method(s) that have taken the place of the rural strain carrier for taking the strain off deadend insulators.

3

In an open wye-open delta bank, the delta winding reads 286 amperes. The bank is providing service at 480 volts. The kVA loading each transformer is

137.2 kVA

The power lost by the conductors when delivering electricity to an end line customer on a certain 4.16-kilovolt distribution line is 60 kVA. If the line was to be converted to 8.32 kilovolts and an equal amount of power is being delivered, the line loss would be __ ?

15 KVA

The individual sine waves of a 3-phase system are ? out of step with each other.

120*

Employees contribute ___ per year on there own behalf to the NEBF

0%

On a running corner, ____ web hoist(s) is/are needed when using a corner restraint bracket tool to give an even pull on the conductor in both directions.

1

The line-to-line voltage in a wye system is ? the voltage across the transformer windings of a wye connected bank.

1.73 times greater than

The minimum long-term bend radius of installed fiber-optic cable is usually specified as no less than _____

10 times the cable diameter


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