ELE Review: Accurate Solutions For Every Question
"What do the following prefixes mean:
a. Micro
b. Kilo
c. Mega
d. Milli Right Ans - a.1/1,000,000
b. 1000 times
c. 1,000,000 times
d. 1/1000
If you know the wattage and voltage, how do you determine the current?
Right Ans - Divide the wattage by the voltage
If you know the voltage and current, how do you determine the wattage?
Right Ans - Multiply the voltage times the current
If a circut is supplied with 100 volts and the total resistance of the circut is
200 ohms, how much current will the circuit draw? Right Ans - 1/2 amp
If a piece of equipment is supplied 208 volts and the ammeter clamped to the
hot line reads 20 amps, what is the wattage of the load? Right Ans - 208 *
20 = 4160
How much voltage is in one hot line? Right Ans - None. Voltage is the
potential difference between two different lines
What happens to current in a parallel circuit? Right Ans - It divides into the
different loads
What happens to the voltage across the loads in a parallel circuit? Right
Ans - It stays the same
What happens to the voltage across the loads in a series circuit? Right Ans -
It divides across the loads
What happens to the current in a series circuit? Right Ans - It stays the
same throughout the series circuit
,In a parallel circuit the total resistance of the circuit wil always be less than
what resistance? Right Ans - The lowest resistance in the circuit
How do you find the total resistance of a series circuit? Right Ans - Add up
the individual resistances
How do you find the total resistance of a parallel circuit? Right Ans - 1 = 1 +
1 + 1 + .....
----
Rt R1 R2 R3
If a circuit is wired parallel, and the supply voltage is 120 volts, each load must
be rated at what voltage? Right Ans - 120 volts
If a circut has two elements wired in series and each is rated at 120 volts,
what voltage must be supplied to the circutin order for the elements to heat at
full power? Right Ans - 120 X 2 = 240 volts
What is the advantage of using higher voltages? Right Ans - Lower currents
and smaller wire size requirements
Is there a negative and positive line in AC power supplies? Right Ans - No.
Hots and neutral
What is the voltage between two hot lines in a 230-volt system? Right Ans -
230 V
What is the voltage between two hot lines in a 208-volt system? Right Ans -
208 V
What is the voltage between a hot line and a neutral in a 230-volt phase
supply? Right Ans - 115 V
What is the voltage between a hot line and a neutral in a 208-volt phase
supply? Right Ans - 115 V
What is the accepted maximum voltage difference between the name plate
voltage and the supplied voltage? Right Ans - Plus or minus 10%
,What is the voltage between any two hot lines of a 230 volt Delta power
supply? Right Ans - 230 V
What is the voltage between a hot line and ground on a 250 volt Delta power
supply? Right Ans - No usable voltage
What is the voltage between any two hot lines of a 230 volt Grounded Delta
power supply? Right Ans - 230 V
Draw a diagram of a 230 volt Grounded Delta power supply. LAbel all of the
voltages and the wild leg Right Ans -
What is the wild leg? Right Ans - A hot leg not directly connected to the
center tapped winding with a very high potential voltage to ground or
neutral
What danger is presented by a wild leg? Right Ans - The high voltage will
damage the control circut if connected to a 120 volt control circuit on a
120/230 volt
machine
What is the voltage between either of the non wild leg hot lines and neutral in
a 230-volt Grounded Delta system? Right Ans - 115 V
What is the voltage between the wild leg and neutral or ground on a 250-volt
power supply? Right Ans - Unknown, but will be a high voltage
How do you determine which hot line is the wild leg in a 250 volt Grounded
Delta power supply? Right Ans - Check each hot line to neutral. Two will
read 115 volts, and one will read a high voltage. The leg with the
high voltage reading to neutral or ground is the wild leg
What danger is there when replacing a three phase circuit breaker in a 230
volt Grounded Delta power supply? Right Ans - Must be careful not to cross
the wiring on the breaker which will change the wiring connection that the
wild
leg is connected to and may damage the equipment
, Why is a ""Wye"" power supply so versatile? Right Ans - Can get 208 V
single and three phase as well as 115 V all from the one power suply
What is the voltage between any two hot lines in 208 volt Wye power supply?
Right Ans - 208 V
What is the voltage between any hot line and neutral or ground in a 208 volt
Wye power supply? Right Ans - 115 V
What is the voltage from any hotline to ground or neutral, on a 480 volt Wye
power supply? Right Ans - 277 V
If you had a commercial building and you had a three phase supply to your
building, how many different incoming
power supplies would you need if the incoming three-phase supply was:
A. Three phase Delta 240 volt?
B Three phase Grounded Delta 230 volt?
C. Three phase Wye supply 208 volt? Right Ans - A. 2 - One for three phase
and one for single phase
B. 1
C. 1
Electricity will always follow what path? Right Ans - Path of least
resistance
Why should all equipment be grounded? Right Ans - Safety, to prevent
electrical shock to operator or anyone else
How should the earth ground from the main fuse or breaker panel be
connected? Right Ans - Jumpered across the water meter if the meter is
used for earth ground
In order for a receptacle to be properly grounded, the ground wire must run
to where? Right Ans - Back to the ground bar in the breaker box
How much resistance should you read from a neutral connection to a ground
connection? Right Ans - None. Voltage is the potential difference between
two different lines
"What do the following prefixes mean:
a. Micro
b. Kilo
c. Mega
d. Milli Right Ans - a.1/1,000,000
b. 1000 times
c. 1,000,000 times
d. 1/1000
If you know the wattage and voltage, how do you determine the current?
Right Ans - Divide the wattage by the voltage
If you know the voltage and current, how do you determine the wattage?
Right Ans - Multiply the voltage times the current
If a circut is supplied with 100 volts and the total resistance of the circut is
200 ohms, how much current will the circuit draw? Right Ans - 1/2 amp
If a piece of equipment is supplied 208 volts and the ammeter clamped to the
hot line reads 20 amps, what is the wattage of the load? Right Ans - 208 *
20 = 4160
How much voltage is in one hot line? Right Ans - None. Voltage is the
potential difference between two different lines
What happens to current in a parallel circuit? Right Ans - It divides into the
different loads
What happens to the voltage across the loads in a parallel circuit? Right
Ans - It stays the same
What happens to the voltage across the loads in a series circuit? Right Ans -
It divides across the loads
What happens to the current in a series circuit? Right Ans - It stays the
same throughout the series circuit
,In a parallel circuit the total resistance of the circuit wil always be less than
what resistance? Right Ans - The lowest resistance in the circuit
How do you find the total resistance of a series circuit? Right Ans - Add up
the individual resistances
How do you find the total resistance of a parallel circuit? Right Ans - 1 = 1 +
1 + 1 + .....
----
Rt R1 R2 R3
If a circuit is wired parallel, and the supply voltage is 120 volts, each load must
be rated at what voltage? Right Ans - 120 volts
If a circut has two elements wired in series and each is rated at 120 volts,
what voltage must be supplied to the circutin order for the elements to heat at
full power? Right Ans - 120 X 2 = 240 volts
What is the advantage of using higher voltages? Right Ans - Lower currents
and smaller wire size requirements
Is there a negative and positive line in AC power supplies? Right Ans - No.
Hots and neutral
What is the voltage between two hot lines in a 230-volt system? Right Ans -
230 V
What is the voltage between two hot lines in a 208-volt system? Right Ans -
208 V
What is the voltage between a hot line and a neutral in a 230-volt phase
supply? Right Ans - 115 V
What is the voltage between a hot line and a neutral in a 208-volt phase
supply? Right Ans - 115 V
What is the accepted maximum voltage difference between the name plate
voltage and the supplied voltage? Right Ans - Plus or minus 10%
,What is the voltage between any two hot lines of a 230 volt Delta power
supply? Right Ans - 230 V
What is the voltage between a hot line and ground on a 250 volt Delta power
supply? Right Ans - No usable voltage
What is the voltage between any two hot lines of a 230 volt Grounded Delta
power supply? Right Ans - 230 V
Draw a diagram of a 230 volt Grounded Delta power supply. LAbel all of the
voltages and the wild leg Right Ans -
What is the wild leg? Right Ans - A hot leg not directly connected to the
center tapped winding with a very high potential voltage to ground or
neutral
What danger is presented by a wild leg? Right Ans - The high voltage will
damage the control circut if connected to a 120 volt control circuit on a
120/230 volt
machine
What is the voltage between either of the non wild leg hot lines and neutral in
a 230-volt Grounded Delta system? Right Ans - 115 V
What is the voltage between the wild leg and neutral or ground on a 250-volt
power supply? Right Ans - Unknown, but will be a high voltage
How do you determine which hot line is the wild leg in a 250 volt Grounded
Delta power supply? Right Ans - Check each hot line to neutral. Two will
read 115 volts, and one will read a high voltage. The leg with the
high voltage reading to neutral or ground is the wild leg
What danger is there when replacing a three phase circuit breaker in a 230
volt Grounded Delta power supply? Right Ans - Must be careful not to cross
the wiring on the breaker which will change the wiring connection that the
wild
leg is connected to and may damage the equipment
, Why is a ""Wye"" power supply so versatile? Right Ans - Can get 208 V
single and three phase as well as 115 V all from the one power suply
What is the voltage between any two hot lines in 208 volt Wye power supply?
Right Ans - 208 V
What is the voltage between any hot line and neutral or ground in a 208 volt
Wye power supply? Right Ans - 115 V
What is the voltage from any hotline to ground or neutral, on a 480 volt Wye
power supply? Right Ans - 277 V
If you had a commercial building and you had a three phase supply to your
building, how many different incoming
power supplies would you need if the incoming three-phase supply was:
A. Three phase Delta 240 volt?
B Three phase Grounded Delta 230 volt?
C. Three phase Wye supply 208 volt? Right Ans - A. 2 - One for three phase
and one for single phase
B. 1
C. 1
Electricity will always follow what path? Right Ans - Path of least
resistance
Why should all equipment be grounded? Right Ans - Safety, to prevent
electrical shock to operator or anyone else
How should the earth ground from the main fuse or breaker panel be
connected? Right Ans - Jumpered across the water meter if the meter is
used for earth ground
In order for a receptacle to be properly grounded, the ground wire must run
to where? Right Ans - Back to the ground bar in the breaker box
How much resistance should you read from a neutral connection to a ground
connection? Right Ans - None. Voltage is the potential difference between
two different lines
