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?

[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?

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/12...provement..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/techreferen...s/Trnsfrmr.pdf