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

[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/f...s/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.