Turns Ratio Worksheet: Transformer Turns Ratio and Input/Output Problems, 2 primary windings, delta, wye,, Motor Drives (12+13), Vocabulary on Transformers (for Electrical Machines & Drives), Drive mechanism and Transformers, Transformer Review, Chap...

When troubleshooting a contactor or motor starter, the voltage is acceptable if the voltage reading is within _____% of the motor voltage rating.

10

In a DELTA system, the coil voltage is 7,200 volts. What is the system voltage?

7,200 Volts

Short

A(n) ______ circuit is a circuit in which current takes a shortcut around the normal path of current flow.

Dead

A(n) ________ short is a short circuit that opens the circuit as soon as the circuit is energized or when the section of the circuit containing the short is energized.

Open

A(n) _________ circuit is an electrical circuit that has an incomplete path that prevents current flow.

How are the secondary winding-ends tagged?

A, B, C, D

A nameplate reads 12,470GRDY/7,200. How many primary bushings does this transformer have?

One H1; the other end of the primary winding is a tank ground

Lower

One method to diminish the harmful effects of long lead lengths between an electric motor drive and a motor is to _____ the carrier frequency.

True

Service factor is a multiplier that represents the percentage of extra load that can be placed on a motor for short periods of time without damaging the motor.

The T-frame used with a 3 phase manual contactor is activated by a _____ mechanism.

pushbutton

The _____ indicator on a trip indicator informs the operator or electrician why the unit is not operating and that it is potentially capable of restarting with an automatic reset.

red

Two-wire control is normally used for _____ installations where an immediate return to service after a power failure is required.

remote or inaccessible

A(n) _____ is used to increase or decrease the strength of the field or armature in a DC shunt motor.

rheostat

In a stepper motor, the permanent magnet is called the _____ or armature.

rotor

Terminal markings S1 and S2 always indicate the _____ field leads.

series

A(n) _____ circuit is a circuit in which current takes a shortcut around the normal path of current flow.

short

To help reduce damage to switch contacts, a(n) _____ circuit is used to protect the switch.

snubber

Because the stator coils are turned on and off rapidly to control a stepper motor, _____ switches are used.

solid-state transistor

The requirements a motor must meet in controlling a load include work, force, torque, and horsepower in relation to _____.

speed

The direction of shaft rotation is controlled by the polarity of the produced magnetic field in the _____.

stator coil

AC contactor assemblies are made of laminated _____, while DC assemblies are solid.

steel

when current flows through both windings in the same direction the polarity is_______

subtractive

In a DC shunt motor, if the _____ to the armature is reduced, the speed is also reduced.

voltage

False

Control wiring should be installed in the same conduit as power wiring.

False

Electric motor drives cannot introduce power quality problems into a power distribution system.

True

Electric motor drives operate satisfactorily only when connected to the proper power supply.

low

Electric motors that are continuously operated at _____ speeds must be derated or provided with auxiliary cooling.

False

Electrical loads operating at lower rated voltages are more likely to be damaged than loads operating at higher rated voltages.

The wires extending from the shunt field of a DC shunt motor are marked _____.

F1 and F2

False

Grounding of an electric motor drive provides equal potential between all metal surfaces and a high-impedance path to activate overcurrent devices.

Anode

Positive electrode

False

Power wiring is all external wiring connected to an electric motor drive, excluding the line and load conductors.

What part of the transformer helps to relieve any buildup of gas inside the tank?

Pressure relief valve

Which side of the transformer is the source side?

Primary Side

Or

What type of circuit logic is developed when two NO switches are connected in parallel?

And

What type of circuit logic is developed when two NO switches are connected in series?

0V

When a switch is used to control a lamp or other load in a 24VAC control circuit, what is the voltage that would be measured across the switch when the switch is closed and the load is ON?

24V

When a switch is used to control a lamp or other load in a 24VAC control circuit, what is the voltage that would be measured across the switch when the switch is open and the load is OFF?

NO and Parallel

When additional switches are to be wired into a control circuit to produce additional START functions, are NO or NC contacts used and are they connected in series or parallel?

NC and series

When additional switches are to be wired into a control circuit to produce additional STOP functions, are NO or NC contacts used and are they connected in series or parallel?

Black

When connecting a DMM to L2 of a control circuit, which color DMM test lead is always used?

What does "Alley-Cat, Bad-Dog" mean?

When paralleling the windings for a WYE secondary, open the lid and connect A and C together to X1, and then B and D together to

two

When using PWM with AC voltage, _____ IGBT(s) is/are used for each phase.

To identify and separate the different component parts included on the individual pieces of equipment

Why are manufacturer's terminal numbers added to a control circuit?

To trace the action of a circuit in complex line diagrams.

Why are numerical cross-reference numbers added to a control circuit?

To keep track of the different wires that connect the components in the circuit

Why are wire reference numbers added to a control circuit?.

Metal

Wiring for digital signals, analog signals, and serial communication signals should be installed in separate _____ conduits.

_____ is produced when a force overcomes a resistance.

Work

A _____ rotor is a condition when a motor is loaded so heavily that the motor shaft cannot turn.

locked

A(n) _____ is the arrangement of contacts in such a way that both sets of contacts cannot be closed at the same time.

mechanical interlock

A(n) _____ should be used for more accurate testing of insulation.

megohmmeter

The electron flow motor rule states that the _____ points in the direction of the electron current flow in the conductor.

middle finger

Stepper motors are used in applications that require precise control of the position of the _____.

motor shaft

It simplifies the understanding of the function of a circuit.

why are line numbers added to a control circuit?

Manual contactors are normally used _____.

with lighting circuits.

_____ primaries are three phase lines with a neutral

wye

Pilot lights

______ signal an operator that any one of a sequence of events may be taking place.

troubleshooting

_______ is the systematic elimination of various parts of a system, circuit, or process to locate a malfunctioning part.

AND

_______ logic is used in industry when two NO pushbuttons are connected in series to control a solenoid.

circle

_______ the wire reference numbers is a common method to help differentiate wire reference numbers from other numbering systems.

Manual Automatic and Manual

________ are signal conditions

Line (ladder)

________ diagrams are one of the oldest and most common methods of illustrating and understanding basic logic functions.

NOT

________ logic is used in a circuit when a pilot light is used to show that an operation has stopped.

OR

________ logic is used in industry when an NO pushbutton and an NO temperature switch are connected in parallel.

Memory

_________ circuits are also known as holding or sealing circuits.

NAND

_________ logic is an extension of NOT logic in which two or more NC contacts are connected in parallel to control a load.

NOR

_________ logic is an extension of NOT logic in which two or mote NC contacts in series are used to control a load.

NOT

__________ logic has an output if the control signal is OFF.

Step down transformer

a transformer that decreases voltage when the primary voltage is greater than the secondary voltage

step-up transformer

a transformer that increases voltage when the secondary voltage is greater than the primary voltage

Contactor and magnetic motor starter modification devices include additional electrical contacts, power power poles, pneumatic timers, transient suppression modules, and _____.

control circuit fuse holders

wye primaries never have a neutral

false

A _____ alloy is a metal that has a fixed temperature at which it changes directly from a solid to a liquid state.

eutectic

a phase rotation indicator is used to check system voltage.

false

all single phase transformers 200kva and under with high voltage winding voltage 8660v amd lower are subtractive polarity

false

in a grounded primary wye system the ground us connected to c phase

false

when connecting a customers service to a three phase transformer bank you do not have to worry about phase rotation.

false

A DC motor consists of _____ windings, an armature, a commutator, and brushes.

field

The intensity of the magnetic field and the amount of current in a conductor are normally changed to increase the _____ on the conductor.

force

bushings hold and insulate the windings from_________ on the transformer tank

grounding out

A(n) _____ coil converts the excess current drawn by a motor into heat, which is used to determine whether the motor is in danger.

heater

the letter ___ represents the high side of the transformer

high side

single phase transformers have a ____ voltage winding and a ______ voltage winding

high, low

The _____ of a motor determines the size of a load that the motor can operate and the speed at which the load turns.

horsepower

A(n) _____ motor protector is an overload device located directly on or in a motor to provide overload protection.

inherent

A motor that is starting draws a tremendous _____ current (normally six to eight times the running current) when the circuit is closed.

inrush

Additional NC contacts are used to turn on additional loads anytime a contactor or starter is OFF, as well as to provide electrical _____.

interlocking

A DC _____ motor should always be connected directly to the load and not through belts, chains, etc.

series

An advantage of _____ contacts is that the oxide (rust) that forms on the metal is an excellent conductor of electricity.

silver alloy

The _____ is the base unit of electrical power.

watt

Nor

what type of circuit logic is developed when two NC switches are connected in series?

Idler

wheel between two other wheels

the low side is represented by the letter ___

x

Spindle

Also known as shaft goes between the wheels

Horsepower (HP) is a unit of power equal to _____ lb-ft per min.

33,000

Open

A switch in the OFF position is A(n) _______ circuit.

A spring placed behind the brush forces the brush to make contact with the _____.

commutator

Speed Ratio Equation

Speed of driver/speed of driven

Types of drive mechanism

The belt drive The chain drive the gear

Which type of connection is phase-to-phase? DELTA or WYE?

Delta

It is estimated that every _____ C rise over normal ambient temperature ratings for insulation can reduce the life expectancy of a motor by almost a year.

1

If 100 volts is supplied to a primary coil wound 100 times, and the secondary coil with only 10 wraps is placed near it, how many volts will be induced?

10 volts

If a motor has an FLC rating of 10 A and an SF of 1.15, the excess short-term current equals _____ A.

11.5

In a WYE system, the coil voltage is 7,200 volts. What is the system voltage?

12470 Volts

A commutator rotates in _____ degree increments.

180

How many "power" transformers are there in a closed-DELTA bank?

2

Transient suppression modules normally consist of resistance/capacitance (RC) circuits and are designed to suppress the voltage transients to approximately _____% of peak coil supply voltage.

200

What is the hot-leg-to-hot-leg voltage (p-p) in a standard 120/208 3ph service?

208 Volts

What is the power leg voltage in a 120/240 3ph service?

208 Volts

A _____ V, 1 phase power source has two hot wires, L1 and L2 (ungrounded conductors), and no neutral.

230

What is the power-leg-to-hot-leg voltage in a 120/240 3ph service?

240 Volts

Overload relay devices are normally rated to trip at a specific current when surrounded by an ambien temperature of _____ C.

40

read-only

A _____ parameter is a parameter value that can be displayed, but not set or changed.

Load

A __________ is the electrical device in a line diagram that uses the electrical power from L1 to L2.

True

A bearing current is the result of induced voltage in the motor rotor created by the electric motor drive.

True

A bypass contactor is a contactor that allows line power to a motor that is normally controlled by an electric motor drive.

True

A capacitor is an electronic device specifically designed to store a charge of energy.

secondary cell

A cell that can be recharged

Transformer

A device that is used to transfer electrical enrgy from one circuit to another by electromagnetic induction

forward-biased

A diode allows current to flow only when it is _____.

True

A disconnect is a device that isolates an electric motor drive and/or motor from the voltage source to allow safe access for maintenance or repair.

False

A fixed resistor is a resistor that contains fixed tap points of different resistances.

True

A fly-back diode is a diode placed across a transistor to prevent high voltage spikes produced by the collapsing magnetic field of the motor windings.

Gear train

A group of 2 or more gears

True

A heat sink is a device that conducts heat away from an electrical component.

True

A line reactor is installed as close as possible to the input of an electric motor drive.

True

A multiple-motor installation requires that all the motors have the same NEMA design letter.

parentheses

A numerical cross-reference system consists of numbers in _______ to the right of the line diagram.

Emergency Stop

A(n) _____ is used where accidental contact with moving equipment, or the unintended flow of product, can result in physical injury or property damage.

nonlinear

A(n) _____ load is any load where the instantaneous load current is not proportional to the instantaneous voltage.

False

A rectifier changes DC voltage into AC voltage.

True

A semiconductor device is an electronic device that has electrical conductivity between that of a conductor and that of an insulator.

Electrolyte

A substance that dissolves in water to give a solution that conducts electric current which has two electrodes

Solid-State

A(n) _____ switch is a device that uses electronic components to open and close circuits at a precise point in time to control current flow and voltage levels.

Gear

A toothed wheel fixed in machines to make different parts move at different speeds and in differnt directions

a. 40:15 or 8:3 ratio b. step down

A transformer has 15 turns in the secondary and 40 turns in the primary. a. what is the turn ratio? b. is this a step up or step down transformer?

a. 200:100 or 2:1 ratio b. step up

A transformer has 200 turns in the secondary and 100 turns in the primary. a. what is the turn ratio? b. is this a step up or step down transformer?

a. 30:60 or 1:2 ratio b. step down

A transformer has 30 turns in the secondary and 60 turns in the primary. a. what is the turn ratio? b. is this a step up or step down transformer?

a. 200:400 or 1:2 ratio b. step down

A transformer has 400 turns in the secondary and 200 turns in the primary. a. what is the turn ratio? b. is this a step up or step down transformer?

Kilovolt ampere

A unit of electrical power equal to 1000 volt amperes

3

A voltage difference greater than _____ % between no-load and full-load conditions indicates that the electric motor drive is underpowered and/or overloaded.

False

A voltage sag is a high-energy, high-voltage, short-duration spike in an electrical system.

Open Loop

A(n) _____ drive is an electric motor drive that operates without any feedback to the drive about motor speed.

Integrated Power Module

A(n) _____ is a grouping of separate parts designed to perform a set of function or task, such as providing a time delay, power gain, or filtering a signal.

Insulated Gate Bipolar Transistor

A(n) _____ is a high power switching device that can switch high currents and high voltages.

Encoder

A(n) _____ is a sensor that produces discrete electrical pulses during each increment of shaft rotation.

Silicon Controlled Rectifier

A(n) _____ is a solid-state device with the ability to rapidly switch high currents.

capacitor

A(n) _____ is an electrical device designed to store electrical energy.

Surge Suppressor

A(n) _____ is an electrical device that provides protection from transient voltages by limiting the level of voltage allowed downstream.

Diode

A(n) _____ is an electronic device that allows current to pass through in only one direction.

OR

Additional start pushbuttons are connected in parallel using _______ logic with the existing start pushbuttons.

NOR

Additional stop pushbuttons are connected in series using _________ logic with the existing stop pushbuttons.

Three

All circuits are composed of _________ basic section(s).

True

An SCR is a solid-state device that controls current according to the amount of voltage applied to the base.

transformer

An electrical machine that transfers electrical energy between two or more circuits through electromagnetic induction.

Digital

An example of A(n) _________ process is a standard light switch that has only two positions: fully ON or fully OFF.

Top

An integrated circuit's notch indicates the ________ of the chip.

True

As the length of conductors increases and/or an electric motor drive's output carrier frequency increases, the voltage spikes become larger.

_____ wear faster than any other component of a DC motor.

Brushes

True

Capacitors oppose a change in voltage and coils oppose a change in current.

What is a "power leg" and what is it used for?

Check to see if it has a ground strap to the case. If it does, remove it or you will short the secondary windings out.

What is a "CSP" transformer and what transformer parts are specific to a CSP?

Completely Self Protecting, and there is an internal primary fuse link and a secondary breaker

Chain drive

Combines the sprocket and chain that mesh together to produce a positive mechanical force

Worm gear

Connects shafts at right angles to each other

speed

Controlling the frequency to an AC motor controls the _____ of the motor.

WYE or DELTA? 240/480 3 ph service

DELTA

Chemical Cells

Devices used to convert chemical energy to electricla energy

a. 10,000 volts b. step down

Determine the input of a transformer if the turn ratio is 200:400 and the output voltage is 5,000 volts. a. input voltage? b. is this a step up or step down transformer?

a. 200 volts b. step up

Determine the input of a transformer if the turn ratio is 500:1 and the output voltage is 100,000 volts. a. input voltage? b. is this a step up or step down transformer?

a. 60 volts b. step up

Determine the input of a transformer if the turn ratio is 6:1 and the output voltage is 360 volts. a. input voltage? b. is this a step up or step down transformer?

a. 60 volts b. step down

Determine the output of a transformer if the turn ratio is 300:600 and the input voltage is 120 volts. a. output voltage? b. is this a step up or step down transformer?

a. 14,666 b. step up

Determine the output of a transformer if the turn ratio is 400:3 and the input voltage is 110 volts. a. output voltage? b. is this a step up or step down transformer?

a. 120,000 volts b. step up

Determine the output of a transformer if the turn ratio is 500:1 and the input voltage is 240 volts. a. output voltage? b. is this a step up or step down transformer?

Top

Each line in a line diagram should be numbered starting with the _________ line

There are two ways to deliver a three-phase service to a customer. What are they?

Either with a three-phase transformer or interconnected single-phase transformers.

What are "bayonet" fuses used for?

Energizing and de-energizing the secondary side of a transformer

The types of belt drive are

Flat belt Round belt Vee belt

Gear Ratio Formula

Gear ratio = Driven teeth / Driver teeth(Na/nb)

single

In residential and small commercial locations, only a(n) _____-phase power source is available.

False

Higher carrier frequencies cause smaller power losses in an electric motor drive.

Parallel with coil or use NO contacts

How is a lamp added into a control circuit so it is ON anytime the motor is ON?

As many as the switch and other controls amp rating allow

How many loads can be connected in parallel per line in a control circuit in which a switch is used to control the load(s)?

one

How many loads can be connected in series per line in a control circuit in which a switch is used to control the load(s)?

False

If control and power wiring must cross, they should cross at a 45 degree angle.

A coil of wire will become energized if it is placed close to another coil of wire that is attached to AC power. What is this phenomenon called?

Induction

True

Inductive loads such as solenoids or the coils of relays and contactors are a common source of electromagnetic interference (EMI) in electric motor drives.

Every effort should be made to select transformers with the same ___________ when paralleling or banking.

Impedances

Drive

In a majority of electric motor drive applications, the _____ provides the overload protection.

What is meant by "Sames-Opposites"?

In an Open-WYE / Open DELTA, if the primary connects sames (H2s are tied and grounded), then the bottoms must connect opposites (X3 connects to X1); must be sames-opposites or vice versa.

Action

In most cases it is the operating coil in the circuit that is responsible for initiating the ________.

True

Inverter drives can typically control motor speed within +/- 1% of the set speed of the drive.

Current Source (CSI)

Inverter drives include variable voltage inverters, _____ inverters, and pulse width modulated inverters.

In an open bank, why would one transformer be bigger, and how is that transformer referred to?

It is larger in kVA because it provides power to the three-phase and the single-phase load; it is called the "lighter" or "lighting" pot

What consideration should be given to the X2 on the "power" transformer?

It is the third phase in a DELTA bank; it's phase-to-ground voltage serves nothing, but its phase-to-phase voltage feeds the three-phase load.

A nameplate reads 12,470GRDY / 7,200 volts. How would this connect to a 4160 / 7200 system?

It wouldn't; It is a single bushing transformer and must be connected as a WYE configuration.

True

Lightning strikes and utility switching cause high-energy-level transient voltages.

_____ overload relays are extremely quick to reset because they do not require a cooling-off period before being reset.

Magnetic

_____ are used to reduce the distance required and yet quench arcs quickly.

Magnetic blowout coils

Serial

Many electric motor drives have the capability to communicate with PLCs, other drives, and PCs via _____ communication.

False

Most electric motor drives are delivered from a manufacturer in NEMA type 4X enclosures.

False

Most people can hear a tone from a motor when it is in the 1 Hz - 3 Hz range.

430

NEC Article _____ is the main code source for electric motor drives.

Part 31

NEMA standard MG-1, Section IV, _____ provides an enhanced insulation requirement for electric motors, allowing compatibility with electric motor drives.

Cathode

Negative electrode

One

No more than ________ load(s) should be placed in any circuit line between the power lines L1 and L2.

Can an Open-WYE / Open-WYE serve a three-phase load?

No, Open WYE secondary only has two phases

In a 240 3ph-3wire service, what happens if one phase gets grounded?

Nothing. It becomes a corner ground, and the 3-phase service is still delivered. You can ground one time at any point in the service

If a transformer nameplate has only one number listed for a primary voltage rating, how should it be connected?

Phase to phase

A nameplate reads 7,200 / 12,470Y. How would this connect to a 7,200 / 12,470 system?

Phase-to-ground or WY

Engineers can choose from three different primary voltage designations when purchasing transformers. What are they?

Phase-to-phase only • Phase-to-phase or phase-to-ground • Phase-to-ground only

A nameplate reads 7,200 / 12,470Y. How would this connect to a 4160 / 7200 system?

Phase-to-phase or DELTA

Ohms

Resistors are classified by a resistance value in _____ and power dissipation value in watts.

True

Reverse bias is the condition of a diode when it does not allow current flow and acts as an insulator.

Which side of the transformer is the load, or customer's side?

Secondary side

True

Since the angle (timing) of the gate firing pulse can be changed, and SCR can vary voltage output.

_____ action is the principal operating mechanism for magnetic contactors.

Solenoid

Types of Gear

Spur gear Worm gear bevel gear

False

Static electricity cannot be discharged by human skin contact.

What does the term "open bank" mean?

That the wye or delta configurations are incomplete

Inverter

The DC bus section of a drive delivers the DC voltage to the _____ section for conversion back to AC voltage.

True

The DC bus voltage of an electric motor drive is typically about 1.4 times the AC supply voltage to a drive.

On a transformer nameplate that lists two primary numbers separated by a slash, which number is the actual primary coil rating?

The Smaller

Saturation

The _____ region is the maximum current that can flow in the transistor load circuit.

Signal

The ________ accomplishes no work by itself; it merely starts or stops the flow of current in that part of the circuit.

Decision

The ________ of a circuit adds, subtracts, sorts, selects, and redirects the signals from the control devices to the load.

Proper transformer selection starts by comparing two things. What are they?

The circuit and service voltages (on the work order) and the transformer voltage/kVA ratings

True

The converter section of a drive receives the incoming AC voltage and changes the voltage to DC.

What are the three main components of a transformer?

The core, the windings, and the insulating fluid

Simple

The dashed line method works well when the control contacts are close together and the circuit is relatively ________

Electrolysis

The decomposition of the electrolytes into its constituents ions(anion and cation) as a result of the passage of current

True

The final connection to the motor should be made with a short length of flexible conduit and standard wire.

False

The frequency applied to a DC motor controls the motor speed.

A transformer has a blue sticker that says "Non-PCB". What does that mean?

The insulating fluid is good; contains no Polychlorinated Biphenyls.

ON

The load is _________ all the time if no control device is included in a line.

False

The lower the carrier frequency, the closer the output current sine wave is to a pure fundamental frequency sine wave.

Complex

The numerical cross-reference method is used on _________ line diagrams.

DC Voltage

The output of a bridge rectifier is a pulsating _____ that must be filtered before it can be used in most electronic equipment.

Torque

The primary function of a motor is to produce _____ to safely drive the driven load connected to the motor.

star-delta transformers

The primary is connected in star fashion and the secondary is connected in delta fashion.

Voltage Drop

The primary limit to the distance between a magnetic motor starter and the motor is the _____ for the conductors

What information would you typically reference the nameplate for?

The primary voltage • Desired secondary voltage • kVA • Impedances are close enough for banking and paralleling • Weight of the transformer for rigging

turns ratio

The ratio of the number of turns on the primary coil of an electrical transformer to the number of the secondary, or vice versa.

Where is the X1 bushing on an additive transformer, as you face it?

The right of the X2

True

The saturation region is the maximum current that can flow in the transistor load circuit.

What is the "power" transformer?

The smaller of the transformers in the DELTA bank; it provides the third phase

What is a tap changer used for on a transformer?

The tap can adjust the voltage by changing the turns ratio. This ensures the proper secondary voltage is delivered to the customer

False

The three terminals of a silicon-controlled rectifier are the anode, cathode, and emitter.

You perform a continuity test on a transformer with two H-bushings. An audible sound is heard when reading between the H1 and the X1. What does this mean?

The transformer has a short between the primary and secondary windings; red tag and remove from inventory.

True

The two general categories of logic integrated circuits are the transistor-transistor logic family and metal-oxide-semiconductor family.

False

The type of enclosure used does not affect the temperature of an electric motor drive.

phase voltage

The voltage between the given phase and neutral

line voltage

The voltage between two lines

secondary winding

The winding connected to the load

primary winding

The winding connected to the supply

drive mechanism

The working part of a machine which transmits power or movement from one part to another

delta-wye transformers

They are common in commercial, industrial and high-density residential areas to supply three-phase distribution systems.

uses of gears

They can be used to transmit power They are used to change speed They enable cars move They change the direction of motion The ensure smooth running under varying speed

What must be done to the secondary coils in a DELTA-WYE bank?

They must be paralleled; AC-B

In a WYE-DELTA bank what must be done to the H2s on each transformer?

They must be tied together, but not grounded or connected to neutra

_____ control provides low-voltage release and low-voltage protection.

Three-wire

In a WYE-WYE bank, what must be done to the H2s on each transformer?

Tie them together and connect to neutral

In a WYE-WYE bank, what must be done to the X2s on each transformer?

Tie them together and connect to neutral

True

To control AC voltages, at least two transistors are used per phase.

underlined

To differenciate between NO and NC contacts, NC contacts are indicated as a number that is _________.

Why is it important to perform a continuity test on a transformer before installation?

To ensure the windings are connected properly and check for shorts

In a WYE-WYE bank, why is it important to parallel the secondary windings?

To get the full kVA rating from the transformer

_____ is exerted on an armature when it is positioned so that the plane of the armature loop is parallel to the field, and the armature loop sides are at right angles to the magnetic field.

Torque

_____ is the force that produces rotation.

Torque

State the polarity rule.

Transformers 200kVA and smaller, with a primary rating of 8,660 volts and below, will be rated additive. All other transformers will be subtractive.

True

Transistors have no moving parts and can switch ON and OFF quickly.

True

Transistors operate at much faster speeds than silicon-controlled rectifiers (SCRs), allowing higher switching frequencies.

Spur Gear

Transmits motion between parallel shafts

Bevel Gear

Transmits motion between shafts that are close

_____ state a problem, its possible cause(s), and corrective action(s) that may be taken.

Troubleshooting guides

series

Two loads must not be connected in _________ in one line of a line diagram.

3300

Typically, electric motor drives must be derated at altitudes above _____'.

11,000 volts

Using a transformer, calculate the missing factor for the following number of primary, secondary turns, and assuming no power loss occurs: primary voltage - 110 # primary turns - 200 # secondary turns - 20,000 secondary voltage - ?

22,000 volts

Using a transformer, calculate the missing factor for the following number of primary, secondary turns, and assuming no power loss occurs: primary voltage - 220 # primary turns - 100 # secondary turns - 1,000 secondary voltage - ?

10,000 turns

Using a transformer, calculate the missing factor for the following number of primary, secondary turns, and assuming no power loss occurs: primary voltage - 220 # primary turns - ? # secondary turns - 100 secondary voltage - 2.2

440 volts

Using a transformer, calculate the missing factor for the following number of primary, secondary turns, and assuming no power loss occurs: primary voltage - ? # primary turns - 5,000 # secondary turns - 500 secondary voltage - 44

50 volts

Using an autotransformer, calculate the missing factor for the following voltages, total number or tapped turns for the autotransformer, and assuming no power loss occurs: primary voltage - 100 # primary turns - 100 # tapped turns - 50 secondary voltage - ?

110 turns

Using an autotransformer, calculate the missing factor for the following voltages, total number or tapped turns for the autotransformer, and assuming no power loss occurs: primary voltage - 110 # primary turns - 220 # tapped turns - ? secondary voltage - 55

50 volts

Using an autotransformer, calculate the missing factor for the following voltages, total number or tapped turns for the autotransformer, and assuming no power loss occurs: primary voltage - 200 # primary turns - 400 # tapped turns - 100 secondary voltage - ?

440 volts

Using an autotransformer, calculate the missing factor for the following voltages, total number or tapped turns for the autotransformer, and assuming no power loss occurs: primary voltage - ? # primary turns - 880 # tapped turns - 110 secondary voltage - 55

Multiple

Vector drives cannot be used to operate _____ motors from the same drive.

What must be done before connecting the customer's load?

Verify the correct secondary voltage with an approved voltmeter

WYE or DELTA? 120/208 3 ph service

WYE

WYE or Delta? 277/480 3 ph service

WYE

Which type of connection is phase-to-neutral? DELTA or WYE?

WYE

Start and Stop a motor

What function does a JOG button perform in a control circuit?

Nand

What type of circuit logic is developed when two NC switches are connected in parallel?

False

When terminating shielded twisted-pair cables, the shield is terminated only at the device end.

First use volt meter to confirm that voltage is off then use ohm meter to check resistance.

When there is a short circuit in a control circuit, what function of the meter is used to test the circuit components before the faulty component is repaired and power is restored?

Jogging

____ is the frequent starting and stopping of a motor for short periods of time.

Speed

_____ control is not possible when operating in bypass mode.

Digital

_____ inputs consist of control devices that provide an on/off signal such as a selector switch.

VVI (Variable Voltage Input)

_____ inverter drives control an AC motor but produce a square wave instead of a sine wave.

Voltage Drop

_____ is the amount of voltage consumed by a device or component as current passes through it.

Carrier Frequency

_____ is the frequency that controls the number of times the solid state switches in the inverter section of a PWM electric motor drive turn ON and turn OFF.

Ambient Temperature

_____ is the temperature of the air surrounding a motor.

Plastic

_____ raceways are not recommended for electric motor drive installations because they do not provide shielding.

Inverter

_____ rated motors that have spike-resistant insulation reduce the damage caused by voltage spikes.

Metal Conduit

_____ serves as a shield, preventing conductors from radiating EMI and protecting conductors from any radiated EMI.

Base

_____ speed is the speed at which a motor develops rated horsepower at rated load and voltage.

Four

_____ transistors are required to control the direction of a DC motor.

Low

_____-energy-level transients cause malfunctions such as processing errors and damage to equipment over time.

Normally, only one _____ unit with one or two contacts is added per contactor or motor starter.

power pole

when current flows one way through low voltage winding and one way through high voltage winding polarity is _______

additive

when connecting three single phase transformers together to form a bank a relationship forms between the high voltage winding and the low voltage winding this is called__________

angular displacement

A DC series motor is a DC motor that has the series field connected in series with the _____.

armature

A(n) _____ overload relay is an overload relay that resets automatically.

bimetallic

Full-wave rectified power is obtained by placing a(n) _____ in an AC power line.

bridge rectifier

DC motors require more maintenance than AC motors because they have _____ that wear.

brushes

the primary and secondary lines connect to the transformers windings that exit the transformer through the ______

bushings

primary cells

cannot be recharged e.g dry cells and mercury cells

A _____ is an overcurrent protection device with a mechanism that automatically opens the circuit when an overload condition or short circuit occurs.

circuit breaker

Most DC motors are designed so that the brushes and the _____ can be inspected without disassembling the motor.

commutator

A commutator connects each armature winding to the brushes using _____ bars (segments) that are insulated from each other with pieces of mica.

copper

Originally, most knife switches were made of _____, which is required replacement after repeated arcing, heat generation, and mechanical fatigue.

copper

Motors operate on the principle that when a _____-carrying conductor is placed in a magnetic field, a force that tends to move the conductor out of the field is exerted on the conductor.

current

A _____ is used to change the amount of current flowing to a motor but reduces the current to a lower value for the overload relay.

current transformer

A _____ is a device used only periodically to remove electrical circuits from their supply source.

disconnect

A(n) _____ is a sensor (transducer) that produces discrete electrical pulses during each increment of shaft rotation.

encoder

For fully reliable motor protection, heat coils should be selected based on the motor _____ rating shown on the motor nameplate.

full-load current

a______ is a conductor when connected allows electricity to flow from one conductor to another

jumper

AC manual starters are selected based on phasing, voltage, starter size, enclosure type, and _____.

number of poles

a single phase trans will have _______ set of secondaries

one

A(n) _____ was an improvement made to the original design of a knife switch.

operating spring

Loose connections in the power circuit of contactors and motor starters cause _____

overheating

to identify three phase connections the industry uses graphic symbols called_____

phasor diagrams

The _____ that is produced by a motor depends on the strength of the magnetic field in the motor.

torque

a phasor diagram is a picture of a systems current and voltage at one given instant

true

because delta do not have neutral the transformer ground will only connect to the pole ground

true

branch circuits coming off wye primary consist of one phase and a neutral.

true

delta primarys are usually a three phase pine with no neutral

true

high voltage bushings have more insulating quality the low voltage bushings

true

phase rotation can be either clockwise or counter clockwise

true

the polarity is the direction the current flows through the low voltage in respect to the high voltage side of winding of any given moment

true

three phase pad mount transformers are single cabinet units

true