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Questions tagged [power]

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14 views

DC Inverter motor AC utilization category

I am looking at specs of an air conditioner unit. It uses DC inverter technology and maximum current listed as 21.5A So are DC inverter motors considered resistive or inductive? What utilization ...
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2answers
23 views

Measuring shaft torque of a small motor

I would like to determine the mechanical output torque and power of a small motor without using expensive strain guages and similar and have come up with the idea of determining the maximum mass that ...
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88 views

Calculate Power for pump

I did a Civil Engineering course some years ago and from my textbook I had a question on a pump with hoses. Unfortunately I haven't been able to find a solution to this yet. A pump feeds two hoses, ...
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17 views

How to know which efficiencies to take into account when calculating power of a certain part of a power transmission system?

I have an example which I am not certain about: So It consists of a friction wheel, whose power $P_{fw}$ we know. The power is used to power the driven machine $Dm$ on a shaft that lies on 2 bearings,...
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14 views

Comparing power requirements of centrifugal pump installations

Hi, I am stuck with a question related to the centrifugal pumps. There are two centrifugal pump installations and it is asked to compare the power requirements for two installations. As in Pa>Pb or ...
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1answer
35 views

off-scale torque measured - what is my torque arm?

I have assembled a benchtop torque measurement stand for evaluating electric motor and controller efficiency. The motor is 49kV , 5kW brushless outrunner. Input power reading is taken from motor ...
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2answers
192 views

Calculating the torque required by an Archimedes screw pump

Given an Archimedes screw pump (shown below) how would you go about calculating the torque required to operate it? I'm assuming a situation where you have to design for a given flow rate, Q (m^3/s) ...
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0answers
58 views

Negative transmit power in dBm

I am calculating the transmit power for $K$ single antenna IoT devices in an Indoor scenario. The receiver has 64 antennas. I am trying to minimize the transmit sum-power, i.e., $\sum_k p_k$, where $...
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1answer
34 views

Why doesn't steam/water flow backwards from expansion in power plant feedwater pump/boiler? [duplicate]

I think i understand the mechanics in a steam locomotive: Fill boiler with water Close off boiler Heat boiler until pressure is sufficient Keep boiler hot and use steam pressure until no more water ...
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2answers
109 views

Do 3 blade wind turbines generate more power than a 9 blade, all else being equal?

After doing some research, I have come to the realization that 3 blade design horizontal turbines have the greatest maximum coefficient of performance. Most sources seem to agree a Cp of ~0.45 at TSR=...
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35 views

Starting of direct current Motor

what happens if starting arm of starter does not return to "OFF" position after a temporary supply failure?
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2answers
86 views

Motor torque calculation, about the units

This link shows a motor torque, power, and speed relationship, as shown below: With regards to its units, how does kW and RPM become equivalent to N.m?
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1answer
63 views

What is the difference between a diffuser and a duct in turbines?

I have been reading this paper, which addresses the advantages of diffusers in cross flow turbines. The abstract says (emphasis is mine): A CP’s extraordinary improving resulted when yaw increased ...
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1answer
190 views

Basetech BT-305 missing resistor

I just modded my Basetech BT-305 laboratory power supply to become an IoT device. Everything works as planned, except the volt display in the multimeter-part of the supply, which is directly shown ...
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1answer
83 views

The torque I need to lift the device and correct gear ratio for the device to be as fast as possible

The device have to climb a pipe vertically. I have a DC motor with power rating 21.2 w, output speed 13360 rpm and maximum output torque 154.4 gcm. My device is 1 kg and I have wheel with 0.012 m ...
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16 views

How to identify trip coil circuits of Circuit Breaker?

Recently I've encountered Cercuit Breaker without any control circuit diagram. Just many teminals and wires without any tag! I want to do timing test of CB. How can I identify trip coil circuit?(Using ...
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1answer
54 views

Calculating max weight capacity of brushless motor

I am having trouble determining the maximum weight capacity a motor can handle. I provided the specs below. The calculations are for the top row or the 580KV model. So to start off,I'm only taking ...
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0answers
20 views

clockwork motor output in joules formula

I'm trying to understand the output of clockwork coils in joules or watts for different coils. You know the pullback car or windup pocket watch mechanism. I have heard it also called power in the ...
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1answer
105 views

What's the history of the 345 kV voltage level in power transmission?

I'm interested in the history of the 345 kV power level for high voltage transmission in the United States. I've got two (and a half) questions: According to this source 345 kV was first applied in ...
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0answers
68 views

Measurement of ICE torque

I'm seeking a precise description of engine torque. We talk about torque in terms of the twisting force that the piston exerts on the crankshaft with a radius equivalent of the rod throw. Assume ...
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1answer
37 views

Relationship heat rate with capacity

I am an economist, so please keep replies simple ;) I am searching for the relationship between heat rate and capacity for gas-fired power plants. Here is what I refer to as heat rate, i.e. the ...
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1answer
19 views

Vibe Table: Increase Peak Force Capability?

I'm driving a small, benchtop vibe table (shaker) with two Crown DSI-1000 PA's, and also cleaning my signal with a DBX 231s EQ. Currently running the system at 6.8 GRMS, but I'm looking to increase my ...
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1answer
850 views

Linear actuator on a scissor lifting table

I am designing a scissor lifting table and I have an issue with the linear actuator. This table should be lifting 100 kg. I studied the problem in two ways : a static study and a power study. My ...
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0answers
22 views

Calculating the proper power of a motor

I'm trying to build a filament extruder with some basic available tools and materials. Simply the main principle of the machine is to insert some amount of plastic raw material ( ABS in our Case ) to ...
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2answers
44 views

Theoretical maximum generated power for a given torque

Being an electrical engineer, I'm hoping someone will help me double-check my math. I have a small circuit that I want to power for years that consumes an average 10uA at 3V. I'd like to power this ...
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2answers
359 views

Calculate maximum acceleration of a car from rest (optimum launch)

First disclaimer: I have a background in math, but I'm no expert in engineering or physics. This is the first question I've ever posted and I think it belongs here, but please let me know if belongs ...
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1answer
50 views

What are the conditions for a signal to be an energy signal and a power signal?

I know how to find the power and the energy of a signal. What I have a problem with is knowing whether a signal is an energy signal or a power signal. According to my teacher, a signal is a power ...
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1answer
71 views

maximum capacity factors of combined cycle gas power plants

What is the maximum annual capacity factor that can be expected of a CCGT plant? I see in US in 2015 the average was about 0.56, but can it be higher? I guess it needs some time for maintenance but I ...
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2answers
137 views

How to design a casting machine?

I was wondering, what are the factors to consider or how to find the required technical specifications for the new machine? For example, if we consider a design of horizontal centrifugal casting ...
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1answer
3k views

Specific energy vs Specific power in batteries

When looking at the Wikipedia page for Lithium-ion batteries, one can see that there are some technical details such as Specific Energy and Specific Power, but I don't know how to connect them. For ...
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2answers
112 views

Is it Possible to Generate Power From Sewage Sludge?

I have read about the application of sewage sludge incinerators1 but they do not have a net-positive power-generation. Is there a way to generate net-power from sewage sludge? What are the processes ...
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1answer
27 views

Connecting power lines around corners

I am working on a model city. Suppose I have utility poles A, B and C (brown) that go around a sharp corner. Looking from above, how do I connect the poles with power lines (gray, solid)? Are the ...
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2answers
2k views

What is the difference between shaft power and brake power?

I know little about internal combustion engines and I feel a little confused about brake and shaft powers. I read a book that only talks about shaft power, and other that only talks about brake power, ...
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3answers
839 views

How to determine the compressor power in a refrigeration system?

The picture below represents a refrigeration unit In order to calculate the power produced by the motor, two quantities must be measured Angular speed of the motor. This parameter can be observed ...
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2answers
33 views

Control power to a tungsten filament?

I'm afraid I'm completely out of my depth here. I would like to use a tungsten filament to radiatively heat something near to it (in vacuum). My issue is I cannot figure out the easiest and/or ...
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2answers
106 views

Intuitive explanation for why doubling max speed is proportional to eightfold power

I read that when you want to double the max speed of e.g. a boat you would have to increase the power eightfold! I could understand that you have to square it (= fourfold) because you are working ...
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0answers
24 views

What is the twisting rate to reduce capacitance load on DC power transmission line?

I need to carry dc (direct current) electrical power from a solar array to point of use. I know that an undesirable capacitive load will develop if I just run the power and neutral wires parallel to ...
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1answer
38 views

How the sizing of electric motor is done for a electric vehicle?

I have calculated the resistances encountered by the vehicle. Now to find the required power i used formula ...
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3answers
973 views

Is torque produced at the crank of an engine lower than at the wheels?

Im specifically referring to motorcycle engines, but for arguments sake a car engine wouldn't matter either Say 100Nm was measured at the wheel using a rolling dyno, then based on the reduction ...
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0answers
43 views

Measuring Helix Angle

What is the best way to measure the helix angle of a helical cut gear? I have a sun gear from a planetary set that I would like to have custom made but I'm not sure the best way to get the helix angle,...
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1answer
356 views

CUF v/s PLF of power plants

What is the difference between capacity use factor (CUF) of solar power plant and plant load factor (PLF) of coal based power plant? Can we compare both since they seem analogous?
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0answers
29 views

Charging a Li-po battery (battery output current)

I would like to design a buck converter to use a PV panel to charge a 11.1V 3000mAh 3S 30C Lipo battery. I want to choose the minimum inductance for a CCM ($L=\dfrac{V_{out}T_s}{2I_{out}}$), what is ...
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1answer
3k views

How to calculate the power/torque/force needed to move a 4 wheeled vehicle?

I am trying to build a "mule": it s basically a go kart chassis with a 12v dc motor (I figured it would be easier to use). Now I need to determine how powerful should the motor be... It is going ...
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1answer
51 views

Feedback on idea for a power station

Hi there, When I was very little I came up with this idea for a power station and I recently remembered it and was curious about the viability. The way it works theoretically is that a voltage supply ...
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1answer
502 views

What is the maximum efficiency of a mechanical electric generator?

If we apply a simple push to rotate a system of gears to generate electricity, what is the maximum practical and theoretical power efficiency of the system, assuming the push as the only source of ...
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1answer
67 views

Split phase on industrial devices

I want to build a professional CNC router for my garage. I want to use the residential split phase configuration for power to my VFD and industrial power supplies. I cannot find any straight answer ...
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3answers
79 views

Radioactive Materials to Energy AT HOME

Is there a way to use a radioactive elements (Americium in my case, but for demo, any radioactive material) to create a usable amount of energy (Power small LED?) AT HOME! Using materials that can be ...
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1answer
51 views

How many batteries can I charge and how long would it take?

Using a hydro generator which gives an output of 4.838KW, I am trying to figure out how many batteries I can charge and how long it would take. I am doing the calculations based on 12V, 17Ah ...
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2answers
2k views

How to calculate hydropower in kW without water head

I am trying to do some calculations to figure out how much power output would be produced from a water powered generator that uses horizontal current flow to move the generators coils rather than ...
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3answers
72 views

How does the second Motor operate in this diagram?

The two motors are mounted in parallel as you can see in the picture and each one of them is connected to a gearbox through an elastic coupling. My question is : how do they operate together ? is one ...