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

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    #21
  1. Join Date
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    Quote Originally Posted by BRAD2121 View Post
    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

  2. #22
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    Quote Originally Posted by stevenl569 View Post
    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 specd 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

  4. #23
  5. dvansick2345 is offline Junior Member Pro Subscriber
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    Quote Originally Posted by iwanttotest View Post
    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

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    Quote Originally Posted by dvansick2345 View Post
    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

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  9. NoWorldOrder is offline Junior Member Pro Subscriber
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    Quote Originally Posted by ElectricalTestTech View Post
    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.

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  11. NoWorldOrder is offline Junior Member Pro Subscriber
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    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)

  12. #27
  13. SecondGen's Avatar
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    Quote Originally Posted by NoWorldOrder View Post
    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/f...s/r-rated.aspx

  14. #28
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    Quote Originally Posted by SecondGen View Post
    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

  16. #29
  17. Wanderer20001us's Avatar
    Wanderer20001us is offline NETA Level III Pro Subscriber
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    Quote Originally Posted by cjones09 View Post
    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.

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    Quote Originally Posted by bcarillon33 View Post
    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?

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