Period 5
As temperature increases, the winding resistance is expected to increase or decrease?
Increase, direct with temperature
What is the formula to find the synchronous speed of a motor?
Synchronous speed(RPM)= 120 x Hz (60) / number of poles
True or false: As a part of LOTO process, all interlocking or dependent systems must also be de-energized.
True
True or false: You should only use one hand when taking measurements in a high energy environment.
True
True or false: some permanently installed loads can create their own transients.
True
True or false: when installing a shorting probe, the first step is to connect the test clip to a good ground contact.
True
True or false: when two arcs join, they create either a phase to phase or a phase to ground fault.
True
On a delta motor winding, which reading remains the same when it comes to line and phase current and voltage?
Voltage
How to find current imbalance?
Voltage imbalance% x 7.5
What is one major cause of arc flash and blast?
Voltage transients (spikes). Resulting from switching reactive loads or lightning strikes
Can a 12 terminal motor be wired in either Wye or delta?
Yes
Do HVAC system and control system prints consist of abbreviation's and symbols, wiring diagrams, detail drawings, and sequence of operations narratives?
Yes
Do most HVAC system prints include a bill of materials?
Yes
Do most HVAC systems control systems prints include a sequence of operations?
Yes
How many watts is 1 horsepower ?
746 watts
PPE category 2 minimum arc rating calories. Also panel-board voltage rating
8 Cal/Cm2 & >240v ac to 600ac
Digital Multimeter rated for CAT 111 1000v has a peak impulse transient voltage and a test source (ohm) of what?
8000v and a 2 ohm source
Digital Multimeter rated for CAT 1V 600v has a peak impulse transient voltage and a test source (ohm) of what?
8000v and a 2 ohm source
What numbers are a good rule of thumb when it comes to what you should see megging large tonnage equipment?
80M ohms @ 80 degrees F
True or false: if you ever blow a fuse in your meter, it is safe to continue using the meter in a high energy environment as long as you replace the fuse.
False
True or false: Direct current (DC) is more dangerous than 60 hz alternating current (AC) of the same voltage and current value.
False AC is three to five times more dangerous than DC.
When it comes to the voltage Imbalance of a load, what percent must the imbalance be within range of ?
2% voltage imbalance
PPE category 4 minimum arc rating calories. Also panel-board voltage rating
40 Cal/Cm2 & 600V
How to find the temperature of a motor winding by using voltage imbalance (formula)
(Voltage imbalance squared) x 2 = the percentage at which the temperature has gone up. Add a 1 infront of percentage and multiply it by the motor temp when there is no imbalance present. Example: motor is 80C with no imbalance, a voltage imbalance of 6.97% is applied to windings. [6.92 squared= 48.58 x 2 = 97.6 ] 1.97 x 80c = 157.6c
Digital Multimeter rated for CAT 11 600v has a peak impulse transient voltage and a test source (ohm) of what?
4000v and a 12 ohm source
When checking the incoming voltage to a load, what percent must it be within range of?
10% of nameplate
How many miliamps is considered fatal?
100 miliamps for 1 second
When it comes to rubber glove ratings, what is a class 0 rated for in voltage?
1000 volts max
What is the maximum current imbalance you can have?
15% current imbalance
PPE category 3 minimum arc rating calories. Also panel-board voltage rating
25 Cal/Cm2 & >240v ac to 600v ac
minimum required motor winding insulation resistance at 40 degrees C for nameplate voltage of 240v to 460v?
300,000 ohms
PPE category 1 minimum arc rating calories. Also panel-board voltage rating
4 Cal/Cm2 & 240v ac and below
Any current flow above how many milliamps is considered dangerous?
5 Milliamps
Generally any voltage above _____ volts is considered dangerous
50 volts
NFPA 70E states that only "qualified persons" are allowed to work on what voltages?
50 volts and greater
When it comes to rubber glove ratings, what is a class 00 rated for in voltage?
500 volts max
Digital Multimeter rated for CAT 11 1000v has a peak impulse transient voltage and a test source (ohm) of what?
6000v and a 12 ohm source
Digital Multimeter rated for CAT 111 600v has a peak impulse transient voltage and a test source (ohm) of what?
6000v and a 2 ohm source
What is power transmission device with a trapezoidal cross section?
A V-Belt
Differentiate between capacitor-start, capacitor-run, and capacitor-start-and-run motors
A capacitor run motor has a capacitor in the starting circuit which is eventually brought out by a centrifugal switch once the motor is up to speed. A capacitor run motor has a capacitor that is constantly in the run circuit throughout operation. A capacitor start and run motor is a motor the incorporates both the capacitor start and run motors attributes.
What is a hasp?
A multiple lockout/tagout device.
What kind of coupling is a inflexible coupling that is used to join two precisely aligned shafts?
A rigid coupling
What is a single phase motor that has separate start and run windings?
A split phase motor
What does ANSI stand for?
American National Standards Institute
What does ASME stand for ?
American Society of Mechanical Engineers
What is a list of major items that make up a control panel along with the sensors and actuators that are mounted in the field?
Bill of materials
What digital multimeter category has a 12 ohm source?
CAT 11
What digital multimeter category's have a ohm source of 2?
CAT 111 & 1V
Most industrial and commercial electricians work in what kinds of environments when it comes to CAT ratings?
CAT 111 & CAT 1V
Which CAT category covers 600V underground cable runs or areas outside of the building installation?
CAT 1V
What is a master list of titles and numbers used to organize specifications and other project information for most building design and construction projects in North America ?
CSI master format
What is a Cal rating? (Cal/Cm2)
Cal/Cm2 is a Reading for what level of incident energy we might expect should an arc flash occur and is directly related to equipment.
Split phase motors incorporate what kind of switches attached to the motor shaft?
Centrifugal switches
What is the current flow through a Megger between the winding and ground?
Charging current
On a WYE motor winding, which reading remains the same when it comes to line and phase current and voltage?
Current
What should happen to the charging current during a megger test on a motor winding
Current flow should stop after the motor is fully charged with current
Every 10 degrees Celsius above design temp will do what to the life expectancy of a motor?
Cut it's life expectancy in half with every 10 degrees C
What kind of test voltage do insulation testers apply? And current level
DC voltage, low current
As temperature increases the winding insulation resistance is expected to increase or decrease?
Decrease, inverse with temperature
Grounding provides a direct path for unwanted fault current to where?
Earth
How often should you replace a hard hat suspension and entire hard hat?
Every year for suspension and every 5 years for entire hard hat
True or false: The safest place to measure voltage on a breaker panel is where the highest energy is available.
False
How to find voltage/current imbalance (formula)
Find the average, find the greatest deviant of the average, divide the deviant into the average and multiply it by 100
When installing new machinery, you must ensure that all framework is what?
Grounded
On a 9 lead dual voltage motor, when the windings are connected in series, is the motor running in high voltage or low?
High voltage
If you have a motor that is rated for two different horsepower and the requirements of equipment fall between the two, which rating are you going with? Higher or lower?
Higher
What device should be used for the manual operation of a high voltage disconnect switch?
Hot stick
How many more amps are locked rotor amps compared to full load amps?
LRA is 6 times the FLA
What are the three general classifications of V-belts?
Light duty, Standard and heavy capacity
On a WYE motor winding, how would you find the phase current?
Line current= phase current
On a WYE motor winding, how would find the phase voltage if you are given the line voltage?
Line voltage/1.73
On a Delta motor winding, how would you find the phase voltage?
Line voltage= phase voltage
What are the two general categories of flexible couplings?
Mechanical and material(such as rubber)
What does NEMA stand for?
National Electrical Manufacturers Association
All facets of the electrical industry apply the ______ as a minimum standard for the installation of electrical systems
National electrical code (NEC)
Do HVAC wiring diagrams provide locations and specifics on mounting and cable wiring?
No
Does PPE 0 exist?
No
Will HVAC system prints provide the exact location of/or mounting information for electrical equipment such as control panels, disconnects, motor starters, or variable frequency drives?
No they will not
What is the difference in attire when it comes to PPE ratings 1 and 2?
PPE 2 introduces the balaclava underneath the face shield
On a Delta motor winding, how would you find the phase current?
Phase current= line current/1.73
What is the difference between locked rotor amps (LRA) and running load amps (RLA)?
RLA also known as full load amps(FLA) is the amperage of the motor running at full load. LRA, also known as starting amperage, is the amount of current drawn on a motor if the rotor is unable to turn or locked up.
How to find resistance total in parallel circuit?
RT= 1/ (1/R1 + 1/R2 + 1/R3)
How to find resistance total in series circuit ?
RT= R1 + R2 + R3
What are the two most common motor mounts?
Rigid and Resilient
What kind of single phase motor operates by use of a small pole wrapped in a thick copper wire that is 90 degrees out of phase and has low starting torque?
Shaded pole
If you have a double pole motor running at a synchronous speed of 3,450 RPM rather than 3,600, why may that be?
Slip
What is an electric output device that converts electrical energy into linear mechanical force?
Solenoid
What kind of single phase motor incorporates a start and a run winding. Typically the start winding is brought out of the circuit by a centrifugal switch once the motor is up to speed.
Split phase motor
What is the Megger test procedure known as dielectric absorption ratio?
Take a reading at 30 seconds, then a reading at 60 seconds on the motor windings. The test is 60 seconds long. Afterwards divide your second reading into your first to get your ratio, anything above 1.6 is excellent.
What is the Megger test procedure known as polarization index?
Take a reading at the motor terminals at 1 minute, then take a reading at 10 minutes. The test is 10 minutes total Divide your second answer into your first to get your ratio. Anything above 4 is excellent
What is a two piece pulley consisting of a tapered outside diameter hub?
Tapered Bore
How to find temperature of motor winding if given the current imbalance?
Temperature= current imbalance squared Current imbalance= voltage imbalance X 7.5 Example: you have a motor winding that is 80c with no imbalance present and is applied with a 2.16% voltage imbalance [2.16% x 7.5 = 16.2%] [16.2% squared= 262.44] 1.262 x 80c = 100.96c
What is the difference between an arc flash and arc blast ?
The light and heat emitted from the explosion is the arc flash, the pressure wave is the arc blast.
What will happen if an exposed live wire makes contact with the metal frame of an ungrounded piece of electrical equipment?
The metal frame will be live
When wearing electrical safety gloves, do the rubber gloves go on first, or the leather.
The rubber goes on first and the leather is meant to protect the rubber
Explain service factor on a motor.
The service factor is a number that represents the amount of extra load that can be placed temporarily on a motor without causing damage. example: if a 20 HP motor has a 1.15 SF, that means the motor can safely run at 23 HP which is 15 % more than the rated amperage.
What is a temperature safety method that protects a motor from overheating?
Thermal protection
If you had a 5% load increase, how much % would your motor temp go up? (Math question) hint: load increase is referring to amps
You would square the 5%. (1.05)2 = 11.5% temp increase. Equation: temperature= current imbalance squared
