Show that, if the stator resistance of a three-phase induction motor is negligible, the ratio of motor starting torque T, to the maximum torque Tmax can be expressed as: TS Tmax 2 1 + Sm Sm 1 ܐܪ where sm is the per-unit slip at which the maximum torque occurs. (10 marks)
Answers
The given statement is about the stator resistance of a three-phase induction motor which is negligible. The ratio of the motor starting torque T to the maximum torque Tmax can be expressed as TS/Tmax = 2s1/(1 + s1²) where s1 is the per-unit slip at which the maximum torque occurs.
It is proven that at starting, slip s=s1, rotor resistance, and rotor reactance are negligible. This implies that the equivalent circuit of the motor can be reduced to a single resistance R2’ corresponding to the rotor circuit and magnetizing branch in parallel with the stator branch. Thevenin's theorem can be applied to calculate the current and torque of the motor at starting.
If V1 is the supply voltage per phase, then the Thevenin's equivalent voltage Vth per phase is given by Vth = (V1 - I1R1) where I1 is the stator current and R1 is the stator resistance. As the stator resistance is negligible, Vth is approximately equal to V1.
Let I2’ be the rotor current per phase, then Thevenin's equivalent resistance R2’ is given by R2' = (s1 / (s1² + R2² / X2²)). Therefore, the Thevenin's equivalent circuit will be as shown below:
Thus, it is proved that if the stator resistance of a three-phase induction motor is negligible, the ratio of motor starting torque T to the maximum torque Tmax can be expressed as TS/Tmax = 2s1/(1 + s1²).
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Related Questions
What is the reading of this Dial Caliper?
Answers
Answer:
45
Explanation:
bdgdsfggsfg
The rafter is fastened to the outside wall so that the plumb cut in the birdsmouth is tight to the exterior wall sheathing
Select one:
O True
O False
Answers
What is the basic requirement of measurements?
Answers
The basic requirement of measurements is to have a standard or reference point against which to compare the quantity being measured. This standard or reference point should be well-defined and stable, and the measurement process should be repeatable and consistent. Additionally, it is important to ensure that the measurement equipment is calibrated and in good working condition.
Answer:
The most basic requirement for measurements is the presence of a standard or reference point against which the quantity being measured can be compared. The measurement process should be repeatable and consistent, and the standard or reference point should be well-defined and stable. Furthermore, ensure that the measurement equipment is calibrated and in good working order.
Explanation:
What time will current of 10A transferred from a charges of 50C
Answers
Answer:
8×10^-19 seconds
Explanation:
i=∆q/∆t
=> ∆t=∆q/i=50×1.6×10^-19/10=8×10^-19(s)
what tag can be used to define the starting point for relative paths?
Answers
The `<base>` tag can be used to definethe starting point for relative paths in HTML.
How is this so?It is placed within the `<head>` section of an HTML document and includes the `href` attribute that specifies the base URL for all relative URLs within the document.
By setting the base URL,you can establish a common reference point for resolving relative paths to external resources such as stylesheets, scripts, and images.
Thus,it is correct to state that `<base>` tag can be used to define the starting point for relative paths in HTML.
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What is a kind of useful car?
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At an operating frequency of 5 GHz, a 50 lossless coaxial line with insulating material having a relative permittivity r = 2.25 is terminated in an antenna with an impedance ZL = 150 . Use the Smith chart to find Zin. The line length is 30 cm.
Answers
Answer:
The answer is "150 \(\Omega\)".
Explanation:
Its line length must be converted into wavelengths for the Smith chart to be used.
\(\to \beta = \frac{2 \pi }{\lambda } \\\\\to u_p = \frac{\omega }{\beta}\\\\\lambda =\frac{2 pi}{\beta} =\frac{2 \pi U_p}{\omega}=\frac{c}{\sqrt{\varepsilon_r f}}\)
\(= \frac{3 \times 10^8}{ 2.25 \times (5 \times 10^9)}\\\\= \frac{3}{ 2.25 \times 5\times 10 }\\\\= \frac{3}{ 22.5 \times 5 }\\\\= \frac{3}{ 112.5}\\\\= 0.04 \ m.\)
\(l =\frac{0.30 }{0.04 } \times \lambda\)
\(= 7.5 \lambda\)
Because it is an integrated half-wavelength amount,
\(Z_{in} = Z_L = 150 \ \Omega\)
Which of the following workers are not likely to be paid during an election?
campaign press secretary
volunteer coordinator
poll worker
director of communications
Answers
Answer:
volunteer coordinator
Explanation:
because they are volunteering for that and in most of the cases they do not expect to be paid
Visit a fire station and obtain information about flow rates through hoses and discharge diameters. Using this information, estimate the impulse force to which the firefighters are subjected when holding a fire hose.
Answers
Water flowing through a flexible fire hose is turbulent flow and consists of a flow field of eddies.
What is the explanation?An eddy-filled flow field characterizes the turbulent flow of water via a flexible fire hose. The pressure against the pipe wall is affected by the turbulent kinetic energy of these eddies because it is shifted from large eddies into smaller eddies. Accelerometers are sensitive to the types of pipe vibrations that are caused by pressure changes.Piezoelectric pressure transducers and piezoelectric accelerometers are two categories of sensors that have been utilized in the literature to measure fluid flow in rigid pipes. Clinch employed a collection of flush-mounted piezoelectric pressure transducers along a water pipe's inner surface to monitor pressure changes brought on by turbulent water flow [11]. The variations in flow rate and pressure were found to be related.
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You may not operate a vehicle unless all child passengers __________ are securely fastened into an approved child restraint device.
Answers
Answer:
You may not operate a vehicle unless all child passengers under the age of 16 years are either wearing a safety belt assembly or are securely fastened into an approved child restraint device.
Explanation:
A regulator is required on a nitrogen cylinder to
Answers
A regulator is required on a nitrogen cylinder in order to reduce very high pressure within the gas cylinder to a safer pressure.
What is a regulator?A regulator can be defined as a mechanical device that is designed and developed to ensure that a controlled amount of nitrogen gas is supplied from a gas cylinder.
This ultimately implies that, a regulator is required on a nitrogen cylinder in order to reduce very high pressure within the gas cylinder to a safer pressure.
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Determine the maximum intensity of loading that can be sustained by a simply supported beam, 75 mm wide x 100 mm deep, assuming perfect elastic-plastic behaviour with a yield stress in tension and compression of 135 MN/m². The beam span is 2 m. What will be the distribution of residual stresses in the beam after unloading? [50.6 kN/m; 67.135. -67 MN/m²)
Answers
To determine the maximum intensity of loading that can be sustained by a simply supported beam, we can use the concept of the elastic-plastic behavior of the beam.Let's consider the given data:Width of the beam = 75 mmDepth of the beam = 100 mmYield stress in tension and compression = 135 MN/m²Span of the beam = 2 mTo find the maximum intensity of loading, we need to calculate the plastic moment capacity of the beam.
We know that the plastic moment capacity of a simply supported beam is given by:M_p=\frac{f_yI}{\sqrt{3}}Where,f_y is the yield strength of the material in N/m²I is the moment of inertia of the beam in m^4Plugging in the given values, we get:M_p=\frac{135\times10^6\times\frac{(0.075\times0.1^3)}{12}}{\sqrt{3}}M_p=67.135~ Nm\text{Maximum intensity of loading}= \frac{M_p}{L}\text{Maximum intensity of loading}= \frac{67.135}{2}=33.567~ kN/m
The distribution of residual stresses in the beam after unloading will be:Compression stresses = -67.135 MN/m²Tensile stresses = 50.6 kN/m, the distribution of residual stresses in the beam after unloading is -67.135 MN/m² and 50.6 kN/m.
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You have enabled encryption for cloud-based virtual machine hard disks. To which term does this configuration apply?
Answers
The term that stands for enabling the encryption for cloud-based virtual machine hard disks is known as Server-side encryption or Bit locker.
What is Cloud encryption?Cloud encryption may be defined as the methodology through which the transformation of data from its original text format to an unreadable format is done.
According to the context of this question, Bitlocker enables disk encryption on Windows VMs. While Server-side encryption enables by default managing all sorts of disks, snapshots, images, etc. in all the regions where regulated disks are significantly available.
Therefore, server-side encryption or Bit locker is the term that stands for enabling the encryption for cloud-based virtual machine hard disks.
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2.3
What does NBT stand for?
Answers
Answer:
Named Binary Tag ( NBT)
Explanation:
The format is designed to store data in a tree structure made up of various tags
The meaning of the given word NBT is called; National Benchmark Test.
What is the meaning of NBT?The meaning of the given word NBT is called National Benchmark Test.
NBT ( national benchmark test ) is defined as a national test which must be written and passed by High school students that intend to go to the university ( i.e. passport to the university ).
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technology has developed a lot since ford’s time. some modern cars don’t need gasoline. some don’t even need drivers. (True or False)
Answers
The statement "technology has developed a lot since ford’s time. some modern cars don’t need gasoline. some don’t even need drivers" is True. Technology has been rapidly advancing in the automobile industry, particularly in the development of self-driving vehicles, electric cars, and various other features.
With the advancements in technology, several cars are made to be autonomous and run on electricity. Electric cars, hybrid cars, and fuel cell cars are common examples of cars that don't need gasoline.
Automated driving technology is a significant technological advancement that aims to reduce driver error and enhance road safety. Self-driving cars, also known as autonomous vehicles, can operate without human intervention thanks to the development of this technology.
They have the potential to eliminate driver errors, lower fuel consumption and harmful gas emissions, and provide transportation to individuals who cannot drive for medical or other reasons.
Therefore, the statement is true.
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6-137 Consider a Carnot heat-engine cycle executed in a steady-flow system using steam as the working fluid. The cycle has a thermal efficiency of 30%, and steam changes from saturated liquid to saturated vapor at 275oC during the heat addition process. If the mass flow rate of the steam is 3 kg/s, determine the net power output of this engine, in kW.
Answers
Answer:
1417.05 kw
Explanation:
From the question,
The Mass flow rate = 3kg
The Saturated temperature = 275⁰c
The Thermal efficiency = 30%
The enthalpy of vaporization is 1574.5kj/kg
Rate of heat transfer = 3x1574.5 = 4723.5 kW
Thermal efficiency of engine =
0.30 x 4723.5
= 1417.05 kW
This answer is the net power output of this engine, in kW.
Thank you!
How many hours must be traveled by car for each hour of rock climbing to make the
risks of fatality by car equal to the risk of fatality by rock climbing? (FAR for car
travelling is 52 and FAR for rock climbing is 3400).
Answers
The number of hours that must be travelled by car to make the risks of fatality by car equal to the risk of fatality by rock climbing is = 65hours
Calculation of risk of fatalities (FAR)The FAR of car = 52
This means for every one hour there is risk of 52 people dying by car accident.
The FAR of rock climbing = 3400
This means that for every one hour there is risk of 3400 dying by car accident.
If FAR for 1 hour = 52
X hours = 3400
Make X the subject of formula,
X hours = 3400/52
= 65 hours approximately
Therefore, the number of hours that must be travelled by car to make the risks of fatality by car equal to the risk of fatality by rock climbing is = 65 hours.
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what happens if your son makes a spark in a outlet and then the room goes dark
Answers
Answer:
He probably tripped the wiring, when metal hits the electricity it creates a reaction that burns the wiring.
Explanation:
what is the relation between the number of transmit antennas and the number of receive antennas for spatial multiplexing to be possible. provide a mathematical argument for your answer.
Answers
The number of transmit antennas should be greater than or equal to the number of receive antennas for spatial multiplexing to be possible. This is because spatial multiplexing is a technique used in MIMO (multiple input multiple outputs) systems that utilizes multiple antennas at both the transmitter and receiver to increase the data rate and reliability of wireless communication.
The number of transmit antennas determines the number of independent data streams that can be transmitted simultaneously, while the number of receive antennas determines the number of independent data streams that can be received simultaneously. Therefore, if the number of transmit antennas is less than the number of receive antennas, there will be fewer independent data streams transmitted than received, which makes spatial multiplexing impossible.
Mathematically, the number of independent data streams that can be transmitted and received simultaneously is equal to the minimum of the number of transmit antennas and the number of receive antennas. This is known as the rank of the channel matrix, which is a measure of the number of independent dimensions of the MIMO channel. If the rank is less than the number of data streams, spatial multiplexing cannot be used, and the capacity of the channel is limited by the rank.
Therefore, to enable spatial multiplexing, the number of transmit antennas should be greater than or equal to the number of receive antennas, and the rank of the channel matrix should be equal to the number of independent data streams. This can be achieved by using advanced signal processing techniques, such as precoding and beamforming, to manipulate the channel matrix and increase its rank.
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A hollow steel composite door with an 18-guage metal facing, hung on butt hinges with nonremovable pins, often with ventilation louvers or glass panels is likely a(n):___________
a) Security class door
b) Maximum security door
c) Average industrial personnel door
d) High security door
Answers
Answer:
Average industrial personnel door
Explanation:
Going by the description in which the door has ventilation louvers or glass panel, this shows that it can never be any type of security door. This is because with louvers or glass panel, it can be easier for any intruder to look or break into the house or space that is intended to be protected fully.
Hence, an hollow steel composite door with an 18-guage metal facing, hung on butt hinges with nonremovable pins, often with ventilation louvers or glass panels is likely an Average industrial personnel door
write three ways of soil investigation of a site
Answers
Open excavation.
Borings.
Subsurface soundings.
Geographical methods.
Which method of freezing preserves the quality and taste of food?
Answers
Answer:
commercial freezing
Explanation:
smaller ice crystals are formed this causes less damage to cell membranes so the quality is less effected
Suppose you want to buy a new car. The car will be used mainly for going to work, shopping, running errands, and visiting friends.
What are your objectives to buy this new car? (Mention two or more).
Answers
2. So it’s easier for you to do leisure activities. (I.e visiting friends, shopping)
you cant mix conventional and synthetic oil fact or myth
Answers
Answer:
Explanation:
myth
For these problems, assume air behaves as an ideal gas with R = 0.287 k J k g K. A compressor operates at steady state and takes in air from ambient 0 kPa, gage and 300 K. The outlet pressure is 50 kPa, gage and 400 K. Determine: the mass flow rate if the inlet area is 10 cm2 and the inlet pressure is -2 kPa, gage. the minimum outlet temperature that is possible for this compressor. the isentropic efficiency of the compressor, assuming no heat loss. if there is a heat loss of 30 kJ/kg, the work required to run the compressor, and the new isentropic efficiency. A turbine receives air at 50 kPa, gage and 800 K. It discharges to 0 kPa, gage, and the outlet temperature is measured as 500 K. The mass flow rate is the same as in the previous problem. Determine: the maximum work the turbine can do under these conditions. the heat loss, if the turbine works isentropically.
Answers
Answer:
Part 1
1) 0.252 kg/s
2) 457.06 K
3) 63.45%
4) 17.96 kJ
5) 44.85%
Part 2
1) 65.92 kJ
2) 57.62 kJ/kg
Explanation:
1) The mass flow rate
The flow velocity is given by the Bernoulli relation;
\(U =\sqrt{ \dfrac{\Delta P}{\rho } }\)
Where:
ΔP = The difference in pressure = 50 - (-2) = 52 kPa
ρ = Density of air = 1.225 kg/m³
\(U =\sqrt{ \dfrac{52,000}{1.225 } } = 206.03 m/s\)
The volume flow rate, V = U × A
Where:
A = Cross sectional area of the of the inlet = 10 cm² = 0.001 m²
Therefore, V = 0.001 × 206.03 = 0.206 m³/s
The mass flow rate = ρ × V = 1.225 × 0.206 = 0.252 kg/s
2) The minimum outlet temperature
P₁v₁/T₁ = P₂v₂/T₂
v₁ = v₂
∴ P₁/T₁ = P₂/T₂
T₂ = P₂T₁/P₁ = 151.325*300/99.325 = 457.06 K
3) The isentropic efficiency no heat loss
h₁ = 300.4 kJ/kg
\(h_{(out \ actual)}\) = 401.3 kJ/kg
\(h_{(out \ isentropic)}\) = 441.9 + (457.06 - 440)/(460 - 440)*(462.3 - 441.9) = 459.30 kJ/kg
The isentropic efficiency, \(\eta _{S}\), is given by the expression;
\(\eta _{S} = \dfrac{h_{in} - h_{(out \ actual)}}{h_{in} -h_{(out \ isentropic)} } = \dfrac{300.4 - 401.3}{300.4 - 459.3} = 0.6345\)
Therefore, the isentropic efficiency, \(\eta _{S}\) in percentage = 63.45%
4) Where there is an heat loss of 30 kJ/kg, we have;
\(h_{(out \ actual \ new)}\) = \(h_{(out \ actual)}\) - Heat loss = 401.3- 30 = 371.3 kJ/kg
The work done = (371.3 - 300.04)*0.252= 17.96 kJ/s
The new isentropic efficiency is given by the relation;
\(\eta _{S, new} =\dfrac{300.4 - 371.3}{300.4 - 459.3} = 0.4485\)
Therefore, the isentropic efficiency, \(\eta _{S, new}\), in percentage = 44.85%
Part 2
1) Turbine mass flow rate = 0.252 kg/s
From
T₂ = P₂T₁/P₁ = 101.325*800/151.325= 535.67 K
h₁ = 822.2 kJ/kg
\(h_{(out \ actual)}\) = 503.3 kJ/kg
\(h_{(out \ isentropic)}\) = 544.7 + (535.67 - 520)/(540 - 520)*(544.7 - 524.0) = 560.92 kJ/kg
The maximum work, \(W_{max}\), is given by the expression;
\(W_{max}\) = Mass flow rate×(h₁ - \(h_{(out \ actual)}\))
\(W_{max}\) = (822 - 503.3)*0.252 = 65.92 kJ/s
2) The heat lost, \(h_{loss}\), is given by the relation;
\(h_{loss}\) = \(h_{(out \ isentropic)}\) - \(h_{(out \ actual)}\) = 560.92 - 503.3 = 57.62 kJ/kg.
The UHRS platform is optimized for Edge/Internet Explorer only. You can still use your favorite browser, but keep in mind that you may experience technical issues when working on UHRS with a different browser than Edge or Internet Explorer.
UHRS is optimized for...
Answers
It is to be noted that all UHRS platforms are optimized for the popular kinds of internet browser applications.
What is a UHRS?The Universal Human Relevance System (UHRS) is a crowdsourcing platform that allows for data labeling for a variety of AI application situations.
Vendor partners link people referred to as "judges" to offer data labeling at scale for us. All UHRS judges are bound by an NDA, ensuring that data is kept protected.
A browser is a software tool that allows you to see and interact with all of the knowledgeon the World Wide Web. Web sites, movies, and photos are all examples of this.
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.An equation of state has the following form: P = (RT)/(v-b) - (a)/(Tv2)
a. Using the principle of corresponding states, develop relationships for a and b in terms of Pc & Tc .
b. Predict the molar volume of O2 at 12.4 MPa and 295 K using the above equation.
c. Compare it with results from ideal gas law and compressibility charts/tables. Explain your findings.
Answers
The principle of corresponding states allows us to relate the critical properties (Pc and Tc) of different substances, enabling the derivation of relationships for a and b in terms of Pc and Tc.
How can the principle of corresponding states be used to determine the relationships for a and b in the equation of state?a. The principle of corresponding states states that the reduced variables of a substance at its critical point are the same for all substances.
Using this principle, the relationships for a and b can be derived as follows: a = 0.42748 ˣ (R^2 ˣ Tc²⁵ ) / Pc and b = 0.08664 ˣ (R ˣ Tc) / Pc, where R is the gas constant, Tc is the critical temperature, and Pc is the critical pressure.
b. To predict the molar volume of O2 at 12.4 MPa and 295 K using the equation of state, we substitute the given values of P and T into the equation and solve for v.
c. The comparison with the ideal gas law and compressibility charts/tables will help assess the accuracy of the equation of state in predicting the behavior of O2 at the given conditions.
This will provide insights into any deviations from ideal gas behavior and the suitability of the equation for different ranges of pressure and temperature.
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What is computer programming
Answers
Answer:
Computer programming is where you learn and see how computers work. People do this for a living as a job, if you get really good at it you will soon be able to program/ create a computer.
Explanation:
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3. Steam is distributed on a site via a high-pressure and lowpressure steam mains. The high-pressure mains is at 40
bar and 350◦
C. The low-pressure mains is at 4 bar. The
high-pressure steam is generated in boilers. The overall
efficiency of steam generation and distribution is 75%. The
low-pressure steam is generated by expanding the highpressure stream through steam turbines with an isentropic
efficiency of 80%. The cost of fuel in the boilers is 3.5
$·GJ−1, and the cost of electricity is $0.05 KW−1·h−1. The
boiler feedwater is available at 100◦
C with a heat capacity of
4.2 kJ·kg−1·K−1. Estimate the cost of the high-pressure and low-pressure steam
Answers
A detailed calculation considering various factors such as efficiency, fuel cost, electricity cost, and heat capacity is necessary to determine the cost the high-pressure and low-pressure steam.
To estimate the cost of high-pressure and low-pressure steam, we need to consider the efficiency of steam generation and distribution, fuel cost, electricity cost, and heat capacity. Here's a step-by-step explanation:
Determine the energy content of high-pressure steam: Calculate the enthalpy of high-pressure steam using the given pressure and temperature values. Convert it to energy units (GJ) based on the heat capacity of steam.steam.Calculate the energy content of low-pressure steam: Use the isentropic efficiency of the steam turbine to find the enthalpy of the low-pressure steam after expansion. Convert it to energy units (GJ).Calculate the total energy content of steam generated: Multiply the energy content of high-pressure steam by the efficiency of steam generation and distribution to get the total energy content.Convert energy content to fuel and electricity costs: Multiply the total energy content by the fuel cost per GJ to get the cost of fuel. Additionally, calculate the cost of electricity by multiplying the total energy content by the electricity cost per KWh.Sum up the costs: Add the cost of fuel and the cost of electricity to obtain the total cost of high-pressure and low-pressure steam.By following these steps, you can estimate the cost of the high-pressure and low-pressure steam considering the provided parameters.
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*Avoid waiting in long drive-thru lines, for example, at fast-food restaurants or banks. Park your car and go in. *When possible, use public transportation, walk, or ride a bike. *Get regular engine tune ups and car maintenance checks. *Join a carpool or vanpool to get to work or school. *Keep tires properly inflated and aligned. Conservation. The choices in the list above help to regulate important biogeochemical cycles as well as conserve important natural resources. Making these good choices impacts several cycles on Earth.
Required:
Which set of answers - biogeochemical cycle; natural resource; consequence - is not affected by the list above?
Answers
Answer:
When possible, use public transportation, walk, or ride a bike
Explanation:
Answer:
water; water; Oxygen enters the waterways and causes an imbalance of plant life to animal life.
Explanation:
