Level III Questions, seen recently (from memory bear with me), help?

[BRAD2121]

I've got a few questions I saw on the exam recently:

1: Which oil test is not required on silicone transformer oil?

2: What is the best way to test a removable temperature sensor on a transformer?
- Meter & Loop check
-Meter & thermocouple tester
- Heater & Meter
-IR camera

3: Best type of motor to use if its going to be speed controlled?
-shunt wound
-induction wound
-series wound
-cant remember the 4th option

4: Circuit breaker time travel analysis, what causes it to take longer?
-Bearing wear
- can't remember all other choices

5: Surge arrestor lead cable in order to reduce impedance?
- short cable no bends (i chose)
- short cable w/ small loops
- short cable w/ big loop
- avoid sharp bends

6: Feeder breakers in a hospital with a 3000A 480V service that serves critical care have to have?
- Ground fault
- shunt trip
- zone interlock
-cant remember 4th option

7: which oil tests do you perform on HV oil switch?
-DGA
-IFT
-Di-electric strength (i chose this one)
-water content

6: what meter shows SF6 gas level
-density
-level gauge
-temp gauge
-can't remember

[Sanjayo]

I've got a few questions I saw on the exam recently:
1: Which oil test is not required on silicone transformer oil?


Great questions. My guess for this one would be interfacial tension based on the table below. Did the question give names or just standard numbers?

192

[BRAD2121]

Great questions. My guess for this one would be interfacial tension based on the table below. Did the question give names or just standard numbers?

192

The question only gave names, not the standard numbers.

[STXERS17]

The question only gave names, not the standard numbers.

1: Which oil test is not required on silicone transformer oil?

It would be Interfacial Tension. I verified with NETA MTS-2015 Table 100.4.3 and ATS-2017 Table 100.4.2

[jwdrowe]

Just to add to this, here are some of the questions that I remember from my recent level 3 exam
An ATS does not transfer from utility to generator. The generator is running and producing voltage. Which of the following is the cause of it not transferring?
A) The breaker feeding the ATS did not open
B) battery does not have enough charge to operate the ATS
C) Frequency of the generator is too low
D) Service only lost one phase

in a zone interlocked low voltage circuit breaker scheme and the trip unit in the breaker responsible for clearing is inoperative, then
A) All breakers in the scheme will trip simultaneously
B) The Breaker closest to the power source will trip
C) All breakers upstream of the fault will trip
D) The downstream circuit breaker will trip

A CT supplies multiple devices. To confirm which devices are connected to it, the output of a single phase 5A source is connected to the X1 terminal of the CT without removing the existing wiring. The expected current at each correctly connected device would be:
A) Measurable but small because most of the 5A test current would return to ground through the CT winding
B) Unmeasurable, because the CT winding would short the test current source
C) Between 1A and 4A with the balance of 5A returning through the CT
D) 4A to 5A, because the CT winding impedance is much higher than the connected load impedance

Coil A is rated for 24vdc, 500mA, and has a resistance of 48Ω. R1 is sized to limit the current in the coil to 500mA. If the supply voltage is 125vdc, what is the power dissipated in R1?
A) 12.0 W
B) 24.0 W
C) 50.5 W
D) 77.5 W

Which of the following statements is true pertaining to network protectors?
A) There is no separate source of control power
B) They use a low voltage contactor
C) There are multiple external sources of control power
D) They use a medium voltage contactor

According to the NFPA 70, what is the max allowable time delay results for a ground fault relay to operate?
A) 1 second at 1200 amps
B) 3 sec at 3000 amps
C) 5 sec at 1200 amps
D) At the actual available fault current
i found that the book said 1 sec at 3000+ amps

What is an effect of neutral to ground connection on the load side of the neutral sensor in a 480Y/277V solidly grounded system?
A) Test feature on the ground-fault relay would not function
B) Ground fault may not be detected by the ground fault relay
C) Ground fault relay will trip at half of its pick-up setting
D) Current will only flow through the closed neutral to ground loop

What does the flag indicate on a pistol grip type circuit breaker control device?

If [cos] increases what other conditions must be present?

During a phasing test across a generator tie breaker cell where both sources have the same rotation, the voltage measure across any one phase (A-bus to A-gen) increases as the phase angle:
A) Increases between 0 and 90 degrees
B) Increases between 180 and 270 degrees
C) Decreases between 180 and 90 degrees
D) Decreases between 90 and 0 degrees

[iwanttotest]

6: what meter shows SF6 gas level
-density
-level gauge
-temp gauge
-can't remember

my answer would be density, can anyone back me up? I found these SF6 density meters from Qualitrol http://www.qualitrolcorp.com/products/sf6-gauges/

[bcarillon33]

Here are some questions from the NETA exam I recently took, any help is appreciated.

1. What is an application for a circuit switcher with a pre-insertion inductor?
A) Transient control w/ high fault currents
B) Transient control for capacitor bank switching
C) Current damping at 12.4kV
D) Current damping above 34.5kV

2. How is lagging power factor improved using a synchronous motor?
A) Raise excitation of field windings
B) Lower excitation of field windings
C) Raise excitation of amortisseur winding
D) Lower excitation of amortisseur winding

3. What are the minimum and maximum test voltages for 15kV metal clad swgr?
A) 27kV ac and 36kV dc

4. Given a magnitude of 15 @ 30 degrees multiplied by magnitude 20 @ 60 degrees?

5. A number of resistors in parallel in series with another group resistors in parallel given two specific points in the circuit @ 240 vac what is the measured voltage?

[ElectricalTestTech]

Well here is my attempt at helping you. Someone please feel free to correct me if I'm wrong.

1. What is an application for a circuit switcher with a pre-insertion inductor?
A) Transient control w/ high fault currents
B) Transient control for capacitor bank switching
C) Current damping at 12.4kV
D) Current damping above 34.5kV

A pre-insertion inductor arrangement is provided for a circuit switcher to reduce audible and electrical noise and to limit transient inrush current and/or voltages upon closing of the circuit by the circuit switcher. Pre-insertion inductors have been introduced as a cost-effective alternative to pre-insertion resistors for controlling capacitor bank energization overvoltages.

I have to go with B

2. How is lagging power factor improved using a synchronous motor?
A) Raise excitation of field windings
B) Lower excitation of field windings
C) Raise excitation of amortisseur winding
D) Lower excitation of amortisseur winding
A Synchronous Motor can be made to operate at unity and leading power factor by just increasing its excitation voltage by increasing the field current. I believe the answer is A. But someone please chime in on this one

[SecondGen]

2. How is lagging power factor improved using a synchronous motor?
A) Raise excitation of field windings
B) Lower excitation of field windings
C) Raise excitation of amortisseur winding
D) Lower excitation of amortisseur winding
A Synchronous Motor can be made to operate at unity and leading power factor by just increasing its excitation voltage by increasing the field current. I believe the answer is A. But someone please chime in on this one

I agree with answer A.

A synchronous motor takes a leading current when over-excited and, therefore, behaves as a capacitor. An over-excited synchronous motor running on no load is known as a synchronous condenser. When such a machine is connected in parallel with the supply, it takes a leading current which partly neutralizes the lagging reactive component of the load. Thus the power factor is improved.

By varying the field excitation, the magnitude of current drawn by the motor can be changed by any amount. This helps in achieving stepless control of power factor.

http://ocw.nthu.edu.tw/ocw/upload/124/news/[%E9%9B%BB%E5%8B%95%E6%A9%9F%E6%A2%B0L1b%E8%A3%9C%E 5%85%85%E6%95%99%E6%9D%90]NCT-tech_Power%20Factor%20Improvement..pdf

[SecondGen]

2: What is the best way to test a removable temperature sensor on a transformer?
- Meter & Loop check
-Meter & thermocouple tester
- Heater & Meter
-IR camera


Suspend the thermometer’s indicator bulb and an accurate mercury thermometer in an oil bath. Do not allow either thermometer to touch the side or bottom of the container.

Heat the oil on a hotplate, while stirring, and compare the two thermometers while the temperature increases. If a magnetic stirring/heating plate is available, it is more effective than hand stirring.

An ohmmeter should also be used to check switch operations. If either dial indicator is more than 5 ºC different than the mercury thermometer, it should be replaced with a spare.

The alarms and other functions should also be tested to see if the correct annunciator points activate, pumps/fans operate, etc.

Transformers: Basics, Maintenance, and Diagnostics - https://www.usbr.gov/tsc/techreferences/mands/mands-pdfs/Trnsfrmr.pdf

[ElectricalTestTech]

Suspend the thermometer’s indicator bulb and an accurate mercury thermometer in an oil bath. Do not allow either thermometer to touch the side or bottom of the container.

Heat the oil on a hotplate, while stirring, and compare the two thermometers while the temperature increases. If a magnetic stirring/heating plate is available, it is more effective than hand stirring.

An ohmmeter should also be used to check switch operations. If either dial indicator is more than 5 ºC different than the mercury thermometer, it should be replaced with a spare.

The alarms and other functions should also be tested to see if the correct annunciator points activate, pumps/fans operate, etc.

Transformers: Basics, Maintenance, and Diagnostics - https://www.usbr.gov/tsc/techreferences/mands/mands-pdfs/Trnsfrmr.pdf

I've done this one multiple times. Candy thermometer and a metal coffee can and a torch.

Use what you've got.

[SecondGen]

Coil A is rated for 24vdc, 500mA, and has a resistance of 48Ω. R1 is sized to limit the current in the coil to 500mA. If the supply voltage is 125vdc, what is the power dissipated in R1?
A) 12.0 W
B) 24.0 W
C) 50.5 W
D) 77.5 W


Step 1: Calculate the needed Voltage Drop by subtracting the 2 voltages

125V - 24V = 101V


Step 2: Calculate the needed Resistance using ohms law: R = V / I

101V / 0.500 = 202 Ohms


Step 3: Calculate Resistor Wattage from the Current and Resistance using P = I2R

0.500 x 0.500 x 202 = 50.5W

[SecondGen]

Which of the following statements is true pertaining to network protectors?
A) There is no separate source of control power
B) They use a low voltage contactor
C) There are multiple external sources of control power
D) They use a medium voltage contactor

Best answer here would be no separate source of control power. Network Protectors obtain control power from the network transformer secondary.

Westinghouse NWP's, for example, use a control power transformer while GE taps right off the line and steps down voltage with resistors. In either case, the network transformer supplies voltage. If the transformer goes down, there is no other source for control power.

B and D are just plain wrong, network protectors don't utilize contactors for operation.

[SecondGen]

During a phasing test across a generator tie breaker cell where both sources have the same rotation, the voltage measure across any one phase (A-bus to A-gen) increases as the phase angle:
A) Increases between 0 and 90 degrees
B) Increases between 180 and 270 degrees
C) Decreases between 180 and 90 degrees
D) Decreases between 90 and 0 degrees

A) Increases between 0 and 90 degrees - Phase angle would be getting larger, with difference in potential (voltage) increasing.

B) Increases between 180 and 270 degrees - Phase angle would be getting smaller (moving towards zero) because its now past 180 degrees, voltage would be decreasing.

C) Decreases between 180 and 90 degrees - Phase angle would be moving back towards zero, voltage would be decreasing.

D) Decreases between 90 and 0 degrees - Phase angle would be doing same as above, moving closer to being in phase (0 volts) meaning voltage is decreasing.

Best answer is A.

[cansbach]

According to the NFPA 70, what is the max allowable time delay results for a ground fault relay to operate?
A) 1 second at 1200 amps
B) 3 sec at 3000 amps
C) 5 sec at 1200 amps
D) At the actual available fault current
i found that the book said 1 sec at 3000+ amps


This is what I found also, so there is technically a right answer. Has any one called out NETA on this? I am finding a lot of questions that don't have a right answer or two right answers. Anyone else feel they are making these tests arbitrary, and like they are written be a six year old? Frustrating.

[ironshovel77]

According to the NFPA 70, what is the max allowable time delay results for a ground fault relay to operate?
A) 1 second at 1200 amps
B) 3 sec at 3000 amps
C) 5 sec at 1200 amps
D) At the actual available fault current
i found that the book said 1 sec at 3000+ amps


This is what I found also, so there is technically a right answer. Has any one called out NETA on this? I am finding a lot of questions that don't have a right answer or two right answers. Anyone else feel they are making these tests arbitrary, and like they are written be a six year old? Frustrating.

I so agree with you it seems the tests have been made to fail and cost the companies more money and time having you take the test two and three times
i would say the answer is A i know that this the max setting by NEC and the max clearing time is 1 sec at 3000 amps its the only answer close very badly worded question

[kenner14]

Step 1: Calculate the needed Voltage Drop by subtracting the 2 voltages

125V - 24V = 101V


Step 2: Calculate the needed Resistance using ohms law: R = V / I

101V / 0.500 = 202 Ohms


Step 3: Calculate Resistor Wattage from the Current and Resistance using P = I2R

0.500 x 0.500 x 202 = 50.5W


thank you this really helped!

[stevenl569]

An ATS does not transfer from utility to generator. The generator is running and producing voltage. Which of the following is the cause of it not transferring?
A) The breaker feeding the ATS did not open ATS is an OPEN TRANSITION transfer, the breaker isn't supposed to open
B) battery does not have enough charge to operate the ATS Since when do batteries operate an ATS?
C) Frequency of the generator is too low ATS controllers monitor generator frequency.
This is probably the correct answer
D) Service only lost one phase This is a reason to initiate a transfer. This doesn't explain why it didn't transfer

I see A as being a possible answer. The ATS that I have worked with have an interlock that will not allow the ATS to close in to the generator if the breaker feeding it from the utility side has not opened. This keeps your generator from feeding back to the utility or down the street to the linean trying to repair the lines.

[jflan13]

I've got a few questions I saw on the exam recently:

1: Which oil test is not required on silicone transformer oil?

2: What is the best way to test a removable temperature sensor on a transformer?
- Meter & Loop check
-Meter & thermocouple tester
- Heater & Meter
-IR camera

3: Best type of motor to use if its going to be speed controlled?
-shunt wound
-induction wound
-series wound
-cant remember the 4th option

4: Circuit breaker time travel analysis, what causes it to take longer?
-Bearing wear
- can't remember all other choices

5: Surge arrestor lead cable in order to reduce impedance?
- short cable no bends (i chose)
- short cable w/ small loops
- short cable w/ big loop
- avoid sharp bends

6: Feeder breakers in a hospital with a 3000A 480V service that serves critical care have to have?
- Ground fault
- shunt trip
- zone interlock
-cant remember 4th option

7: which oil tests do you perform on HV oil switch?
-DGA
-IFT
-Di-electric strength (i chose this one)
-water content

6: what meter shows SF6 gas level
-density
-level gauge
-temp gauge
-can't remember

Thank you for the questions, they are a big help

[ElectricalTestTech]

I see A as being a possible answer. The ATS that I have worked with have an interlock that will not allow the ATS to close in to the generator if the breaker feeding it from the utility side has not opened. This keeps your generator from feeding back to the utility or down the street to the linean trying to repair the lines.


An automatic transfer switch is an open transition (break before make) when using it on a utility and generator. Therefore, your ATS is already preventing a backfeed to your utility. There is no need to open the feeder breaker. It is possible it were spec’d That way for your job, but extra control wires would need to be run to monitor breaker status and remote close and trip from the ATS. This is not a common practice. “A” is definitely not the correct answer on a test

[dvansick2345]

my answer would be density, can anyone back me up? I found these SF6 density meters from Qualitrol http://www.qualitrolcorp.com/products/sf6-gauges/

I would of said density or level but I'm not sure

[ElectricalTestTech]

I would of said density or level but I'm not sure

Density meters are on sf6 circuit breakers and switches. They have a red zone and a green zone. Green zone is safe to operate. If they drop to the red, usually there are electrical interlocks that will not allow you to operate the breaker or switch.

Sf6 is heavier than air. Pull up videos on myth busters to see what you can do with sf6. You can inhale it just as you would helium to make your voice drop to a satanic level. You can put sf6 in a fish tank and make paper boats that float on top of the sf6. While you can do these things, Be very careful.

If sf6 is involved in any type of fault or explosion, a white powdery residue is left behind. This is toxic and Needs to be treated as such. It needs to be handled properly by qualified personnel

[NoWorldOrder]

An ATS does not transfer from utility to generator. The generator is running and producing voltage. Which of the following is the cause of it not transferring?
A) The breaker feeding the ATS did not open ATS is an OPEN TRANSITION transfer, the breaker isn't supposed to open
B) battery does not have enough charge to operate the ATS Since when do batteries operate an ATS?
C) Frequency of the generator is too low ATS controllers monitor generator frequency.
This is probably the correct answer
D) Service only lost one phase This is a reason to initiate a transfer. This doesn't explain why it didn't transfer

The correct answer is D. All I can think of is that the question is asking about an ATS that is only monitoring one phase. Also to consider, in MTM transfer schemes (which I've written the logic for many times) the end-users do not want a transfer on a single phase going to ground. They want the HRG to handle it and then to let the motors run on two phases while they track it down.

Anyway, the correct answer is D. Had the same question.

[NoWorldOrder]

R rated fuses are used for:
A- Overload for motors
B- Overload for XFMRS
C- Protection for motors
D- Protection for XFMRS

(I hate how it lays the answers out as "overload" vs "protection)

Winding test results on a motor indicate possible degradation when the output waveforms show:
A-Winding waveform symmetry
B- Noticeable difference in winding waveforms
C- Chopped waveforms on grounded windings
D- Chopped waveforms on phase ungrounded windings

All three phases are the same length, what is acceptable microohms

(I forgot the options, but there was only one that had less than 50% delta)

Undervoltage protection for a UPS should:
A- Inhibit the ATS
B- Open the AC input breaker
C- Start the generator
D- Open the inverter input breaker

4/0 grounded cable is rated at 43kA for 15cycles. What is the minimum number of cables per phase required to safely ground a 2500kVA 5.75%Z transformer on the 480V side

A-1
B-2
C-3
D-4

What is the smallest conductor size allowed for temporary protective grounds?
(forgot the options)

[SecondGen]

R rated fuses are used for:
A- Overload for motors
B- Overload for XFMRS
C- Protection for motors
D- Protection for XFMRS

(I hate how it lays the answers out as "overload" vs "protection)



The "R" rated motor circuit fuses should be selected to coordinate with the motor and controller to provide short circuit protection. The actual “R” rating signifies a 20 second blow point at 100 times the “R” rating of the fuse.

For example: 2R fuse opens in 20 seconds at 200 amperes.

R-rated fuses provide required short-circuit protection for medium voltage motors, motor controllers and associated circuitry. These components have limited ability to absorb the energy of large short circuit currents.

Medium voltage motor controllers contain overload relays which provide both overload protection and locked rotor protection to the motor. The controllers are also intended to interrupt low value short circuits within the capability of the motor controller.

This protects the medium voltage R-rated fuse from sustained overcurrents which are less than their minimum interrupting rating.

http://www.littelfuse.com/products/fuses/medium-voltage-fuses/medium-voltage-fuses/r-rated.aspx

[mmcjagger]

Step 1: Calculate the needed Voltage Drop by subtracting the 2 voltages

125V - 24V = 101V


Step 2: Calculate the needed Resistance using ohms law: R = V / I

101V / 0.500 = 202 Ohms


Step 3: Calculate Resistor Wattage from the Current and Resistance using P = I2R

0.500 x 0.500 x 202 = 50.5W
other methods find total resistance(series cct current same)125/500mA=250 Ohms
R1 resistance will be 250-48=202 ohms
Power dissipated in R1 (I2R) 0.5.0.5.202=50.5W
voltage drop across R1(101V)VI 101.0.5=50.5W
v2/R=101.101/202= 50.5W

[Wanderer20001us]

Looking for help on this question. These are my thoughts, what do you think?

A. This could be possible, the question doesn't state if the utility available light is still on or not
B. Not sure what type of ATS we are dealing with
C. Question doesn't specify the application but I would think any sync issues would be resolved at the gen switchboard
D. This would be a cause for transfer, so this answer is probably incorrect

Thanks in advance.

My 2 cents

A. A breaker "not opening" is not a typical operating is not a normal sequence of operation, so I don't believe this is the answer.
B. I'm not aware of ATS units that use battery for transfer operation. On primary switchgear, yes, when switch breakers, but this seems to be focused on a low voltage ATS, so I'm not inclined to choose this answer.
C. It is possible for the generator to output acceptable voltage but at a frequency under the acceptable pick-up for the Emergency source, so this is my front runner for the desired answered.
D. Agree that this is not likely the answer.

[Wanderer20001us]

Here are some questions from the NETA exam I recently took, any help is appreciated.

1. What is an application for a circuit switcher with a pre-insertion inductor?
A) Transient control w/ high fault currents
B) Transient control for capacitor bank switching
C) Current damping at 12.4kV
D) Current damping above 34.5kV

2. How is lagging power factor improved using a synchronous motor?
A) Raise excitation of field windings
B) Lower excitation of field windings
C) Raise excitation of amortisseur winding
D) Lower excitation of amortisseur winding

3. What are the minimum and maximum test voltages for 15kV metal clad swgr?
A) 27kV ac and 36kV dc

4. Given a magnitude of 15 @ 30 degrees multiplied by magnitude 20 @ 60 degrees?
a × b = |a| |b| sin(θ) n with the resulting vector 90 degrees to the 2 vectors.

5. A number of resistors in parallel in series with another group resistors in parallel given two specific points in the circuit @ 240 vac what is the measured voltage?

[hy3533]

Step 1: Calculate the needed Voltage Drop by subtracting the 2 voltages

125V - 24V = 101V


Step 2: Calculate the needed Resistance using ohms law: R = V / I

101V / 0.500 = 202 Ohms


Step 3: Calculate Resistor Wattage from the Current and Resistance using P = I2R

0.500 x 0.500 x 202 = 50.5W

is that means that two resistors connected in series?

[ray12taylor]

An ATS does not transfer from utility to generator. The generator is running and producing voltage. Which of the following is the cause of it not transferring?
A) The breaker feeding the ATS did not open
B) battery does not have enough charge to operate the ATS
C) Frequency of the generator is too low
D) Service only lost one phase


I just completed the Exam today and this question was on it. However, it had more to the scenario. Something to the effect of the utility power was lost at the start. This to me helped me to rule out D which implies the power was not completely lost. I chose C in the end.

[ray12taylor]

According to the NFPA 70, what is the max allowable time delay results for a ground fault relay to operate?
A) 1 second at 1200 amps
B) 3 sec at 3000 amps
C) 5 sec at 1200 amps
D) At the actual available fault current
i found that the book said 1 sec at 3000+ amps


This one was also on mine and one of the choices was 1 sec at 3000 amps which is exactly what you found. I would like to know what book it was found in??

[ray12taylor]

I would of said density or level but I'm not sure

The answer is Density. I remember this bening a topic of discussion from one of the pop quizzes in the NETA World publications in the last couple years. Its also somewhere in the study guide that NETA has. The one with a combined set of pop quizzes from all past issues.

[mwallace]

The correct answer is D. All I can think of is that the question is asking about an ATS that is only monitoring one phase. Also to consider, in MTM transfer schemes (which I've written the logic for many times) the end-users do not want a transfer on a single phase going to ground. They want the HRG to handle it and then to let the motors run on two phases while they track it down.

Anyway, the correct answer is D. Had the same question.

I humbly disagree with NoWorldOrder in that the question states that the generator is running and is at voltage. If the system is monitoring a different phase than a 'single phase event', there would be no start command to the genset. I believe the answer is that frequency is not in the transfer band to give the ATS a permissive. IMHO anyways, for what that might be worth.

[kingRADi88]

Step 1: Calculate the needed Voltage Drop by subtracting the 2 voltages

125V - 24V = 101V


Step 2: Calculate the needed Resistance using ohms law: R = V / I

101V / 0.500 = 202 Ohms


Step 3: Calculate Resistor Wattage from the Current and Resistance using P = I2R

0.500 x 0.500 x 202 = 50.5W

Late to the game response, I know, but you don't even need to calculate the resistance. Do the KVL to figure out voltage drop of 101 volts, then multiply by 500mA since total current flows through both components, and power is as easy as PIE (P=I x E).

[richardsa]

Well here is my attempt at helping you. Someone please feel free to correct me if I'm wrong.

1. What is an application for a circuit switcher with a pre-insertion inductor?
A) Transient control w/ high fault currents
B) Transient control for capacitor bank switching
C) Current damping at 12.4kV
D) Current damping above 34.5kV

A pre-insertion inductor arrangement is provided for a circuit switcher to reduce audible and electrical noise and to limit transient inrush current and/or voltages upon closing of the circuit by the circuit switcher. Pre-insertion inductors have been introduced as a cost-effective alternative to pre-insertion resistors for controlling capacitor bank energization overvoltages.

I have to go with B

2. How is lagging power factor improved using a synchronous motor?
A) Raise excitation of field windings
B) Lower excitation of field windings
C) Raise excitation of amortisseur winding
D) Lower excitation of amortisseur winding
A Synchronous Motor can be made to operate at unity and leading power factor by just increasing its excitation voltage by increasing the field current. I believe the answer is A. But someone please chime in on this one
In the old days the utility used synchronous motors to control reactive power. They would not drive a load. By control of the excitation current they could off-set and bring the power factor close to unity.

[jfoster]

Looking for help on this question. These are my thoughts, what do you think?

A. This could be possible, the question doesn't state if the utility available light is still on or not
B. Not sure what type of ATS we are dealing with
C. Question doesn't specify the application but I would think any sync issues would be resolved at the gen switchboard
D. This would be a cause for transfer, so this answer is probably incorrect

Thanks in advance.

My though is that a battery should not be involved with an ATS, loss of phase should cause a transfer. I would think it would be a sync check issue. If it could not sync it would not transfer.

[Warrengarber]

This one was also on mine and one of the choices was 1 sec at 3000 amps which is exactly what you found. I would like to know what book it was found in??

Wouldnt it be 1 second at 1200amps? The max allowable ground fault setting is 1200amps.

[Wanderer20001us]

Wouldnt it be 1 second at 1200amps? The max allowable ground fault setting is 1200amps.

See NEC 230.95 (A) Max pick up setting is 1200A. Maximum time delay is 1 sec for fault current of 3000A or more. What the answers seem to imply is that 1 second it the maximum delay from pick up setting to 3000A. Most GFR's I can think of on bolted pressure switch setups have a definitely time delay after pickup with max of 1 sec, so the time delay would be 1 sec at 1200A pickup. Electronic breakers with GF can have I^2T slope functions, and the knee point at pickup can be above 1 sec, but is always below 1 sec by 3000A. But this would allow for a timing at a 1200A pickup of 2 secs in many cases. Code only specifies that the time delay has to be 1 second or less at 3000A.

[Warrengarber]

See NEC 230.95 (A) Max pick up setting is 1200A. Maximum time delay is 1 sec for fault current of 3000A or more. What the answers seem to imply is that 1 second it the maximum delay from pick up setting to 3000A. Most GFR's I can think of on bolted pressure switch setups have a definitely time delay after pickup with max of 1 sec, so the time delay would be 1 sec at 1200A pickup. Electronic breakers with GF can have I^2T slope functions, and the knee point at pickup can be above 1 sec, but is always below 1 sec by 3000A. But this would allow for a timing at a 1200A pickup of 2 secs in many cases. Code only specifies that the time delay has to be 1 second or less at 3000A.

Thank you. I bet that is one that I have been missing and thinking I got it right. Much appreciated!!