Questions tagged [power]
The power tag has no usage guidance.
116
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27 views
Charging a 2020 M1 Macbook Pro from a low-voltage solar array
I'm working on a small project to mount solar panels to a Macbook case which would allow it to charge/offset battery consumption.
I noticed that I was able to power the Macbook on public transport ...
-1
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0answers
36 views
Power Over Fiber Utilization
I've heard of power over fiber for sensitive electronics?
But can you power big devices with fiber optic lines say a big computer, an electric motor, etc?
1
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1answer
425 views
How much power does it take to supply a laser which delivers 100 watts? [closed]
To enable the functioning of a laser which delivers--on average--100 watts of energy in its beam, how much power does it take?
(Does the 2nd law of thermodynamics dictate that the average power ...
1
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0answers
33 views
Power calculations for starter motor designing [closed]
Let's consider an IC engine standard type motorcycle. What is the power needed from the starter motor to start it's engine? Please make all the calculations by taking suitable assumptions like the ...
1
vote
2answers
72 views
How to drive variable power (up to 1500w) to a grill heating element [closed]
I have a heating element like the following:
which is rated to 1500W. I need to be able to drive up to 1500W of power to it, but potentially less. I will be plugging it into a 120V wall outlet.
I am ...
1
vote
1answer
40 views
how much power is needed to move a linear axis
Ι need help calculating the power usage for a linear axis motor. it must move up and down at a maximum speed of 0.5 m/s a load of 50 kg
What I did so far:
The load (i.e. weight) acting on the motor ...
3
votes
1answer
126 views
Does electricity go through non-metal materials or not?
Ever since I was a little boy, I've always had this idea that electricity can only go through metal materials. For example, if I put a 100% metal screwdriver into the socket in the wall, I'm going to ...
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0answers
19 views
Power distribution problem in multi-camera usb array
Problem Summary
My MacBook Pro (development system) can successfully capture images from 24 cameras in the multi camera assembly we have assembled. But when our assembly is attached to a new Raspberry ...
1
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0answers
20 views
Why doesn't the Stress Power in the theorem of the expended mechanical power contribute to the kinetic energy?
The following is the formula of the expended mechanical power:
$P(t)$ $=$ $\frac{d}{dt}$ $\int \frac{1}{2} \rho\ v^2 dV$ $+$ $\int \sigma \colon d\ dV$
where $P(t)$ is the mechanical power entering ...
2
votes
2answers
81 views
Sun as water pump in underpressure water power circle
Introduction
A water storage power plant pumps water up to a reservoir when there is more power available than needed and lets the water flow down when power is needed.
For pumping water up, ...
1
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1answer
24 views
Is there a positive displacement compressor that can rival axial compressors in terms of air mass flow to weight ratio?
Is there a positive displacement compressor that can rival axial compressors in terms of air mass flow to weight ratio?
1
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2answers
86 views
Integrating torque over time
I cannot seem to be able to find which unit applies to the integral of torque over time. If you compress a bracket shaped load cell, you exercise torque on it, say 5 Nm.
Now, say you do this for 5 ...
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0answers
10 views
How can you calculate the specific fan power of a fictitious HVAC system?
I am working on a concept involving an HVAC system drawing air in from outside.
Known information: Air flow rate (calculated), change in pressure accross fan (given) and total efficiency (assumed). No ...
1
vote
2answers
76 views
What happens if an entire country turns off all lights and electric devices during peak consumption hours? [duplicate]
I've been reading about smart grids but I studied Computer Engineering and my already limited knowledge of power systems is very rusty. I keep hearing that traditional power stations have to adjust ...
1
vote
1answer
27 views
Weibull distribution Units - ENGIEQSOL
I am using Engineering Equation Solver, and it has been telling me the units of my distribution are inconsistent.
According to a the book I am reading, I think it should be unitless (as it is a ...
0
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1answer
50 views
Why am I getting wrong value here?
A man threw a ball with force 10 N to two displacement of 5 m and 10 m.
F = ma, so let mass be 2 kg.
a = 5 m/s2.
Work done = 10 × 5 and 10 × 10 = 50 Nm and 100 Nm.
Now, since a = 5, I assumed that ...
1
vote
1answer
38 views
Can we say kinetic energy is tangential K.E?
I saw this in my textbook that
$\dfrac{\text{d}K}{\text{d}t} = \dfrac{\text{d}(1/2mv^2)}{\text{d}t}= F_t v$ where $F_t$ is the resultant tangential force on the body.
Now, let $F_t= F\cos\theta$
$$\...
2
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0answers
42 views
Overcurrent protection, limit for nominal current or stall?
Background: I'm currently working on a robotics design that will drill through soil.
I have selected a 48V motor who's nominal current is 3.17A and has a stall current of 42A. I will be driving the ...
2
votes
3answers
61 views
Relation between armature voltage and mechanical power in electrical Engineering
I am searching for an effect chain that leads to the mechanical power $P_{mech}$ of a DC motor, starting with the applied armature voltage $U_{A}$. My request also includes all the electrotechnical ...
20
votes
4answers
4k views
How does turning off electric appliances save energy
We all know if we use less electricity we save energy.
But the energy we're getting is result of burning (not necessarily the literal meaning) the fuel. Even if we don't use that energy that fuel is ...
1
vote
1answer
80 views
Is using a 4x4 bolted to the face of 2x12 enough?
I am working on a project that has three 2x12’s supporting a load of 12,000 lbs. similar, but not exactly, to how joists support a house.
The 2x12’s are supporting about 6,000 lbs. on each end.
The ...
2
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0answers
29 views
Why 'battery storage power stations' use mainly liion batteries?
As I understand liion batteries have lower lifetime, than LiFePO4. Why would such big stations use liion batteries then? Wouldn't replacement cost large amount of money? And how long those liion ...
3
votes
1answer
55 views
Power a microcontroler with a motorcontroller?
I have a motor controller that operates at 10-50V and draws 5A controlling a 3V motor that draws less than 1A.
I had a an idea where I want to try to use a microcontroller to control this set up.
The ...
1
vote
1answer
68 views
Does the strength of a servo motor depend on the motor or the power?
I am making a life-size robotic dog, and i am having trouble with getting it to walk as it is too heavy for my 4 micro sg servos. Can i make the servos more powerful with more power? If not i can just ...
3
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0answers
62 views
PMDC Motor Characteristic Graph
I am trying create a graph similar to as shown below. However, I am confused as to how the torque is related to the characteristics.
The graph that is to be replicated for certain parameters:
The ...
2
votes
1answer
30 views
Transformer Phase Fault
I have a transformer for troubleshooting.
It is a 3 phase DELTA-WYE Step down (11KV/400V) transformer, the low side voltages (secondary) are
Line to line voltages:
RED-YELLOW : 400 V
YELLOW - BLUE :...
0
votes
1answer
38 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.
2
votes
1answer
23 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 ...
3
votes
1answer
53 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 ...
2
votes
1answer
28 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 ...
2
votes
1answer
35 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
83 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 ...
1
vote
1answer
18 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 @...
3
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0answers
41 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
votes
1answer
15 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?
1
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3answers
118 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
28 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 ...
2
votes
3answers
269 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
135 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, ...
1
vote
1answer
85 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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vote
2answers
2k 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) ...
2
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0answers
103 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 $...
1
vote
1answer
45 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
votes
2answers
141 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=...
1
vote
1answer
81 views
Starting of direct current Motor
what happens if starting arm of starter does not return to "OFF" position after a temporary supply failure?
-1
votes
2answers
1k 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
109 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 ...
3
votes
1answer
484 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 ...
0
votes
1answer
213 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 ...
1
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1answer
389 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 ...
