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

[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/techreferen...s/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