# Tag Info

7

No, this is not classed as a "short-circuit". This is a circuit with a designed current flow - ie a 60 to 150A range is common... A "short-circuit" is a circuit where the current flow is not following the designed current path ie it is taking a "shorter" route to ground.

6

The part of the movie transcript you're talking about (taken from here) is where Fred Halse says: Batt B, no volts, amps are okay. Batt C, s***. No volts, only two amps. They may die before the main chutes open. To make sense of it, I think we need to ground ourselves with the real Apollo 13 and basic electronics. A battery can have zero volts across ...

5

Firstly, by temporal I think you mean spatial. Secondly if you consider acceleration, the units are m/s^2. Seconds-squared are not spatial, but they are temporal. But they needn't be either. Consider E=mc^2. c is the speed of light. Your formula comes from these two formulas: P = I V In other words, the power consumed by a device is equal to the voltage ...

5

Measuring the conductivity of water is actually one of the standard ways of measuring its salinity. The figure below (taken from this University of British Columbia page) shows that the relationship over many orders of magnitude is $$\sigma\propto S,$$ where $\sigma$ is the conductivity and $S$ is the salinity. They further note that the conductivity ...

4

The welder you are using forms a very large inductive loop when the contacts are welding. Any conductive materials you bring within that loop will form one half of a transformer, and they will "steal" some of the energy meant to go into the weld. In order to break this effect you need to eliminate conductive paths within the magnetic field developed by the ...

4

The "rated" value is the maximum safe value for each parameter, not necessarily the actual value for any particular working condition. The current when the motor is running will depend on the load. If you were testing it with no load, the current will be lower. Presumably the pump specification (not the motor spec) will tell you the conditions (flow rate, ...

3

You can have brushless DC as well, but its all a balancing game of cost over its lifetime. Efficiency only matters when the entirety of the process is considered. One high efficiency process can be useless if it forces you into a low efficiency one later. AC can be generated directly off something that rotates. If you smooth it out to DC, you lose some ...

2

This can be due to the rated current is showing the initial start current which can be greater than the running current. The supply needs to be fused to cope with the start current as, if you put a fuse matched to the running current, it would blow on start-up. You probably won’t be able to measure the start ( or in-rush) current with that meter, you would ...

2

For whatever reason standards bodies seem to prefer to give a tabulated list of values without giving any rationale to how those figures were obtained. I once tried to do some first-principles reasoning on this. Let $S$ be the surface area per unit length of the cable, $R$ be the resistance per unit length of the cable, $P$ be the power that can be safely ...

2

There are tables by various standards authorities which give current ratings for various wire gauges based on their insulation, bundling, free-air, conduit, etc. If you find one of those and plot the data you can generate your own best-fit curve. You might be able to get it down to a quadratic equation for a certain range of wire sizes.

2

The 1.5 HP motor is built to draw a specific amperage at full load at 240V. Because power equals voltage times current, a lower than rated voltage will draw more amps through the motor. So if your supply is 208, your current will increase by a ratio of 240/208, or about 15%. Low voltage/high amps is a common failure mode for hand power tools being used ...

2

That is an oversimplification. From the data sheet http://www.ti.com/lit/ds/symlink/lm2596.pdf there are two relevant features, internal over-temperature protection and a maximum current limiter (Typical value 4.5A, minimum 3.6A). The bottom line is that trying to get more than 3A continuous current from the regulator will probably not end well.

1

Lenovo ADL170NLC3A has an Energy Star V (ES 2.0) rating. Energy Star states to get that rating for nameplate output power ($P_{no}$) > 45W, the Minimum Average Efficiency in Active Mode ≥ 87%. At nominal conditions of 170W, 20V @ 8.5A, and a minimum efficiency of 87% implies 195W input. So worst case, the ac charger consumes 25W. The AC adapter is a ...

1

I suggest that you take a closer look at typical noise. I have highlight the area of the specification for you reference. The best method is to confirm is measure the output to confirm the output.

1

As far my knowledge a dynamo is a motor which provides electricity when the rotor shaft is rotated. A dynamo will give DC output. An alternator will give AC output. If I connect multiple dynamos in a single shaft will I get more current? Yes, if the mechanical drive continues to run at the same speed. Adding electrical load will add mechanical load to ...

1

My question was based on an appearance that the thin winding wire seemed to violate the laws of physics, so there might be some other factors at play. Neil_UK answers this in generator coils: max power given wire gauge on the Electrical Engineering site. The bottom line is no. It's mainly a matter of using multiple coils in parallel to manage the current ...

1

Note: Small Gauge mean the wire can carry a significant amount of current. Example per the attach AWG 4-5 can carry 100A. There are lot other factors need to be considered before selecting a wire. Below is guide line help you appreciate wire gauge vs current. This is purely a guideline. I suggest searching American Wire Gauge Charts vs Electrical Current ...

1

Look up ERW ( electric resistance welding ) , this is commonly used to weld steel pipe and tubes ( not necessarily round). Spot welding and projection welds have similar aspects.

1

Torque should be proportional to current, whether stalled or not. Measure the current at stall. Is it what you expected? It should be just the applied voltage divided by the DC resistance of the motor coils that are switched in. Also consider that there can be significant ripple on the torque over a rotation. This is especially true for mechanically ...

1

You will need variable frequency drive (VFD) with "regenerative braking" or a "braking resistor"(the cheaper option) for this application. "Braking" is not necessarily a standard feature (especially on small VFDs) so you will have to specify it. A common configuration is to have the VFD output a frequency proportional an input(0-10v or 4-20mA). They can ...

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