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3 answers
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Why doesn't the work piece melt when arc welding if a lot of amperes run through our electrode?

I am recently learning the theory of Manual Arc Welding. So far I have seen that our electrodes are connected to a machine that outputs hundreds of amps. The work pieces is electrically connected ...
AB2's user avatar
  • 11
0 votes
1 answer
70 views

What causes a correctly sized circuit breaker to trip?

I have a suicide shower head and even though the breaker is correctly sized it trips after about 6-8 minutes of showering.
Osvaldo Silva's user avatar
0 votes
1 answer
45 views

How to find pixel density in LED Display Board?

How to find pixel density in LED Display Board? How do we compare pixel per inch and dots per inch? In this example, a screen of 16'x9' is shown. How did they calculate 4875x2710P and 975x548p and so ...
Ibrahim Omer's user avatar
0 votes
1 answer
267 views

Heating pump/refrigerator - calculate efficiency

I'm wondering how I can calculate the overall thermal efficiency of my heating/refrigerator pump. Actually I have this AC/heating pump unit from Samsung (P/N: AR09TXFYBWKNEE). I've placed a power ...
MadSch's user avatar
  • 101
1 vote
0 answers
39 views

Household 3 phase devices

So, I'm not sure if this is the right place to ask this, but have been working on modifying a lawn mower robot that has, for roughly 3 years now been stored under less than favorable conditions. As a ...
Mat NX's user avatar
  • 265
1 vote
2 answers
283 views

Do piezoelectric materials produce a current flow or just an electric field?

I was watching a video https://www.youtube.com/watch?v=uvT3XvDSSQw about piezoelectric materials. They mentioned that "a current can flow when a pressure is applied to the material". I have ...
user134613's user avatar
0 votes
0 answers
54 views

A regenerative braking system, what am I doing wrong?

I am currently working on a system of regen braking using two DC motors one of them is driven by the motor controller and the other one is using the main motor to spin in cases of full load and in ...
FGS's user avatar
  • 1
0 votes
3 answers
616 views

AC/DC Laptop adapter power losses

I have a laptop power adapter shown in the picture below. It is written there 170Watt INPUT: 100-240V ~ 2.5A OUTPUT: 20V 8.5A I believe for AC Input they mean Root mean square voltage/current. for ...
Zlelik's user avatar
  • 115
1 vote
5 answers
218 views

Ice Bank Cooling

Ice Bank Cooling A century ago when mechanical refrigeration was just coming into use, Ice Banks were a common way to cool large infrequently used areas. Large tanks of water were located in special ...
Richard Illyes's user avatar
0 votes
1 answer
468 views

Are AC generators more efficient than DC generators?

I've been doing some research into AC and DC generators, and I was wondering if AC has any advantages in terms of efficiency. Given that AC generators are usually brushless while DC generators ...
Jack's user avatar
  • 11
0 votes
0 answers
39 views

Synchronization Checks on transformer

Hello I am reading a book about transformers and confused by the following paragraph about synchronization check. When the transformer trips or is taken out of service, the primary and secondary ...
Krack's user avatar
  • 21
2 votes
0 answers
57 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 ...
gunter's user avatar
  • 321
1 vote
0 answers
41 views

Understanding the RMS noise for a given bandwidth

I would like to ask a technical question regarding the current source Keithley Series 2400 Model 2450. I am looking for a high stability current source capable of feeding some Hall probes with a ...
jeb's user avatar
  • 11
0 votes
1 answer
53 views

Determining stability of a current souce from the datasheet. How to?

Is there any way to calculate the stability of an instrument such as current sources and digital voltmeters from their datasheet? Let me provide one example. My application requires stable current ...
jeb's user avatar
  • 11
-1 votes
1 answer
28 views

How can I get more power out from a windmill motor?

As far my knowledge a dynamo is a motor which provides electricity when the rotor shaft is rotated. My Question to be brief is if I connect multiple dynamos in a single shaft will I get more current? ...
Dhrubojyoti Dey's user avatar
1 vote
2 answers
283 views

Is there well known equation (formula) to calculate maximum practical current which copper wire of fixed diameter can handle

I found many online calculators or tables which can give maximum current for the wire. Like 1 mm diameter can handle up to 10 Amperes, 2 mm diameter wire can handle up to 30 Amperes, etc. Is there ...
Zlelik's user avatar
  • 115
1 vote
1 answer
3k views

Running a well pump rated for 230V on 208V power

I have a well with a 1.5 HP pump. The pump is rated for 240V input. At the moment, the only nearby available power is 4-wire 208Y 3phase. I am considering connecting two of the three phases to the ...
Diogenes Creosote's user avatar
0 votes
1 answer
243 views

current limiting through opamp

In this tutorial here There's a current limiting application where two op amps are being used to limit the max output current. The first differential opamp with 4 equally sized resistor values; ...
eeguyee's user avatar
  • 43
2 votes
1 answer
20 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?
eestudent's user avatar
1 vote
0 answers
82 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 ...
yurtesen's user avatar
  • 111
0 votes
2 answers
711 views

How can thin wire in generator windings carry the high output current?

I observed the rebuilding of a 12KW, 120V gas-powered generator. I was amazed at how small the generator portion was (roughly the size of an electric motor you might find in a major home appliance). ...
fixer1234's user avatar
  • 146
3 votes
1 answer
2k views

Short circuit in welding

All I know about welding is it is a technique in which electrode is connected to one terminal and the gripper connected to workpiece is in connection with the other terminal. As current passes and ...
Shwetha's user avatar
  • 97
1 vote
2 answers
3k views

Why is the Current to Motor less than Motor Rated Current?

I have a motor for a submersible pump with a Rated Current of 8.4A as given in the motor's electrical data. However, when it is running, I record a current of 3.4-3.9A. Is there a fault I am supposed ...
Tino M's user avatar
  • 41
0 votes
1 answer
41 views

Steel surface welding with high-frequency current

High-frequency currents induce skin-effect resistance that is used on some applications to weld metals. Assume you have two steel rectangles of dimension $h_0, w, l$ and $h_1, w, l$ placed together ...
lurscher's user avatar
  • 109
2 votes
1 answer
306 views

Stall Torque of a DC Motor Less than Theoretical Values

I have an unknown DC motor with specifications I was testing. I used a Prony Brake setup and scale to evaluate torque, a tachometer for RPM, and multimeters for voltage and current. I get a linear ...
yma3's user avatar
  • 21
-5 votes
1 answer
127 views

In the equation for power as a function of current and resistance, what do the two factors for current represent?

In the electric power equation $P=RI^2$, $P$ represents the product of $RII$. I'm trying to understand the fundamental anatomy of the $RII$ term. More precisely, why does the current, $I$ appear ...
Kris's user avatar
  • 101
6 votes
1 answer
4k views

In the Apollo 13 mission, how could the batteries have "no Volts" with two Amps of current?

In the movie Apollo 13 there's a scene when the LEM is losing power; when they switch the module on, one of the astronauts reads the levels and says that one battery has no Volts but 2 Amps. What did ...
user6396's user avatar
1 vote
1 answer
90 views

Will AC Motor Maintain Speed of Descending Object

Suppose we have an AC motor which needs to lower an object at a set speed. We use a PID loop to determine and correct positional errors. Presumably the PID loop will keep the current low as most of ...
M-R's user avatar
  • 137
4 votes
1 answer
587 views

How does conductivity $\sigma$ of salt-water depend on salinity?

In what way does the electrical conductivity $\sigma$ (or conversely, resistivity $\rho = 1/\sigma$) depend on the salinity $S$ of the saline- (or sea-) water? I know they must be in some way ...
Harry Smith's user avatar
3 votes
1 answer
127 views

What materials or techniques can I use to reduce this electrical effect when building spotwelding tables?

I have been experimenting with building various support tables around press-type spot-welders. These are relatively simple fixures; think of a tabletop with legs under it and devices like sliding ...
Mike's user avatar
  • 131