Questions tagged [power]

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1answer
33 views

What happens if you wire two solar panels in series and parallel at the same time?

Will anything bad happen? Or is it safe.
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1answer
22 views

AC Harmonics on a system appearing as DC

I have a theoretical question about harmonics and DC. Given I have a circuit which has a power supply providing an AC input(230Vrms @ 50Hz), this then goes into a load which, takes this supply ...
2
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1answer
31 views

Power formulae without phasors

I wanted to derive the formulae for active, reactive and apparent power. While I understand the concept of phasors, I think I would find an analytical proof that doesn't involve phasors, more ...
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1answer
25 views

What are the characteristics of a motor that will generate current and is powered by a 30 cc, 2-stroke small engine?

Problem: I am trying to hobby-build a generator using a (old, working, throw-away gas, yard blower) 30 cc, 2-stroke engine. The 2-stroke engine will spin a motor and I want the motor to generate DC ...
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1answer
20 views

How can a curve in Gabrielli-Von Karman graphs curve down?

Gabrielli-Von Karman graph plots the specific power, that is, power required to move certain weight, against speed. It gives an idea how much power is required to move certain mass at a certain speed ...
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1answer
79 views

Required power to spin fan at certain RPM

I have a flat piece of wood shaped like this: And it is turning around axle. What i would like to know is, if it is rotated e.g. at 1000 RPM, how much power would that take? I know that drag force ...
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1answer
14 views

Measuring EM radiation power over surface area

I didn't make it obvious enough below that I was interested mostly in infrared, as the current use case is measuring power radiated from warm objects and from the ground. As pointed out in comment by @...
2
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0answers
39 views

Understanding transformer secondary winding

I purchased a step down transformer from a junk yard. I tested the transformer and it works but I am confused as to the secondary winding. The primary side has these markings G 0V 100V The secondary ...
2
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1answer
14 views

Maximum amps from a switching voltage regulator

Looking at a part like this LM2596 It is rated for 3Amps with a voltage range from 3.3-12 volts. Does that mean that this voltage regulator will only output a maximum of 3amps?
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3answers
50 views

Attaching Gear onto Motor

I want to attach a 12 toothed spur gear with a bore diameter of 6mm onto the shaft of this motor (6mm diameter). How would I go about doing this? From what I see, the shaft is smooth so is my only ...
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0answers
12 views

Design concept, how to power a guage?

I have a 12V battery that I want to monitor using a fuel gauge IC, should the fuel gauge be powered by the 12V battery? Or something else? (can you please provide an example if so?)
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0answers
19 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
93 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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0answers
114 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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1answer
71 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
1k 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
74 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
39 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 ...
4
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2answers
126 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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1answer
60 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
395 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?
3
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1answer
82 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 ...
2
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1answer
332 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
142 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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1answer
205 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
26 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 ...
4
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1answer
304 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
92 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 these ...
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1answer
48 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
22 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
1k 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
23 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
45 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 ...
2
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2answers
670 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
74 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
90 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
144 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
5k 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
121 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
32 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 ...
2
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2answers
3k 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
1k 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
39 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 ...
3
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2answers
108 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
27 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
40 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
2k 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
50 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
510 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
34 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 ...