Developing Electrical Troubleshooting TPC

Thermal overload relays can generally be reset after cooling for about

1 minute

NEMA recommends seasoning linear lamps for _____ hr before dimming

12

When troubleshooting a starter, if line voltage is present, the problem is probably in the

? mechanical,hydraulic, or pneumatic

On an electrical diagram, a control relay is indicated by the designation

CR

Which of the following is not typically used to identify conductors in a motor-control circuit?

Colors

Which of the following provides both overload protection and short-circuit protection in one unit?

Combination motor starter

Most equipment manufacturers adhere to some kind of standard for electrical prints and symbols; the most widely used is the one proposed by

JIC

The color temperature of the light produced by a lamp is expressed in degrees

Kelvin

Which of the following are NOT typically connected to a control relay?

Motors

Which type of occupancy sensor detects the difference in heat emitted by humans in motion from that of the background space?

PIR sensor

Which of the following would show where the power-distribution system, ducts, and manholes are located for a manufacturing plant consisting of several buildings?

Plot plan

High temperature is an indication of a(n) __________ pole-phase group in a polyphase stator

Shorted

Which are most affected by overvoltage?

Slow-speed motors(not sure)

Which of the following is NOT a common cause of mechanical vibration?

Worn brushes

An open armature winding in a dc motor is indicated by

a decrease in speed

Deterioration in a selenium rectifier is indicated by

a gradual rise in the input current

If one phase of a three-phase, Y-connected winding is shorted, the ammeter will indicate

a higher current in the shorted phase

Operation of an air-piloted valve is initiated by

a surge of air

Cross-references to the different locations of limit switches in a diagram are provided by

arrows next to the symbol's line number

The ____________ contacts on a motor starter provide a parallel path for the current to the coil

auxiliary

A gaseous discharge lamp, such as a fluorescent or an HID, requires a(n) ____________, to provide proper starting voltage and regulate current.

ballast

One of the best ways to learn about new equipment is to begin troubleshooting

before installation

A latched electrical relay is an example of a

bistable

In a pneumatic circuit, leakage of air during the actuating part of the cycle

can usually be ignored

Dimming high-pressure sodium HID lamps can cause

color shift

The systematic testing of all controls in a building to ensure that they perform and interact properly is known as

commissioning

DC motors and generators have ____________, which cause special problems not normally found in ac machines.

commutators and brushes

On a building blueprint, a solid electrical line generally indicates a ____________ in the ceiling, while a dashed line indicates the same thing concealed in a concrete floor.

conduit

When you test a three-phase, delta-connected winding with a compass, the compass will indicate alternating north and south poles when the pole-phase groups are

connected properly

When preparing an elementary diagram, you should number all lines with __________ numbers

consecutive

If you close the contacts of a motor controller and measure a potential difference of zero between the motor terminals, the fault is probably in the

controller

If you find a defective relay coil, you should replace it. Test the new coil for proper ____________ with a ____________.

current clamp on ammeter

One added feature of newer motor starters is a single-phase sensor that detects

current unbalance

In a pneumatic circuit, a check valve allows flow in only one direction. In an electrical circuit, this function is performed by a(n)

diode

When troubleshooting combination starters, the number-one symptom of a problem is the operator saying, "The motor ____________."

does not run

In a shunt motor, the field windings are separately ____________ so they carry just a fraction of the load current compared to the full load current of the series motor's field windings.

excited

The following symbol represents an ____________ outlet in a ____________.

exit light; wall

On architectural working drawings, an electrician is concerned mainly with the electrical drawings superimposed on the

floor plan

The no-load current in a three-phase rectifier is typically 6 to 10% of the ____________ current, and usually includes the cooling fan motor.

full load

In autotransformer input circuits, each input line should be

fused

The three most common causes of electrical failure in three-phase motors are shorted, ____________, and burned out windings.

grounded

Planned lighting maintenance primarily consists of _____ to economize on labor, _____ to optimize light levels and space appearance, and _____ to correct abnormalities in operation

group relamping; fixture cleaning; troubleshooting

Each motor in the plant should bear a metal tag with the __________ stamped on it

inventory number

A sequence of operation

is used with an elementary diagram

A helpful piece of information to have when revising a control circuit is the ____________ wire or relay number. This information keeps you from having to hunt through the whole schematic for it.

last

A relay that has "dogs" located directly above the operating bar is called a ____________ relay

latching

A detailed step-by-step description of all input commands, logic responses, outputs and machine motions is provided on the

log

A good diode has a resistance that is

low in one direction, high in the other

Overvoltage, excessive current and too-frequent operation are possible causes of

magnetic coil is burned or short circuited

On a rewound three-phase motor, occasionally an entire pole-phase group may be accidentally reversed. This results in overheating and an increase in the ____________ of the machine

magnetic hum

On a rewound three-phase motor, occasionally an entire pole-phase group may be accidentally reversed. This results in overheating and an increase in the ____________ of the machine.

magnetic hum

The first step in troubleshooting a fluorescent lighting system is to

make sure the lamp is seated properly and contact is good

The kind of lubrication that should be used in a bearing is determined by the bearing's

maximum operating temperature

Most reversing starters with low-voltage remote pushbuttons are all of the following EXCEPT

mechanically interconnected

Mechanical linkages of motor contacts, relays, and solenoids on new equipment should

move freely

Commutator overheating is sometimes caused by the direction of rotation of the motor being changed without changing the position of the brushes to the new ____________ plane.

neutral

In the identification 8TR15XTO, the X indicates

normally closed

You can measure the current in the leads of a three-phase motor with a clamp-on ammeter; the continuity of the motor is tested with a(n)

ohmmeter

On a reversing starter, mechanical interlocks are used to prevent both sets of three-phase contacts from being operated at the same time. The closing of ____________ operates a mechanism that prevents the closing of the opposite contactor.

one contactor

A power-installation drawing shows

only power outlets

Maintained start-stop devices provide

only undervoltage release

Adding limit switches to the control circuit of a reversing motor provides

overtravel protection

The ____________ circuit of an electrical schematic is the simplest part of the diagram and the easiest to follow.

power

A riser diagram shows the

power distribution wiring from input through output

If you suspect that a ground fault is the cause of a machine's electrical problem, make careful checks with the

power off

When you arrive to troubleshoot a defective machine, the next thing to do after talking to the machine operator is to

press the START button

Most methods of reducing motor speed when using multispeed controllers involve the operator

pressing the STOP button

A film of oil on the commutator does all of the following EXCEPT

prolong brush life

Operating a heavily loaded motor at __________ can cause a high slip

reduced voltage

When checking faults in a single-phase, split-phase motor, test both the ____________ windings for grounds, opens, and shorts.

run and start

Rapid-start fluorescent systems are ____________ circuit systems

series

In the electronic timing relay, the time-delay assembly is connected in

series with the relay coil

On a blueprint, wall outlets are indicated by a circle with a

short line drawn to it

A one-line diagram shows paths of energy transfer rather than individual current paths. For example, to show a three-phase, four-wire circuit, it would use a ____________ line ____________.

single; for all the wires

Most control cycle faults are remedied by locating and correcting ____________ errors, which can be very difficult to diagnose.

switching

In addition to the locations of lighting and lighting panels, lighting diagrams show the locations of

telephone outlets

All of the following are common reasons why a split-phase motor makes a noticeable noise when operating, EXCEPT

too little end play

If a motor stops for no apparent reason and you are called to inspect the motor starter, the first thing you should check is the

trip levers on the thermal overload relays

Changing the number of magnetic poles in the stator of a squirrel-cage motor permits the motor to run

two or more fixed speeds

A circuit that provides undervoltage release and has two wires connected to the pilot device that energizes the magnetic control circuit is said to have

two-wire control

Mixing brush grades in a dc motor causes

unequal load distribution among brushes

The NEC requires a fuse to be installed in all __________ conductors

ungrounded

Worn or damaged ball and roller bearings are easily detected by the ____________ they produce.

unusual noise

A pneumatic shuttle valve is used for operating a conventional pneumatic ____________ or electrical relay from either of two control sources.

valve

The actual location and routing of circuits is shown on a

wiring diagram

Open circuits in split-phase motors are most often caused by loose or dirty connections of the centrifugal switch. Sometimes noisy operation of the motor is caused by a(n) ____________ centrifugal switch.

worn