electrical questions

[Gene Sp]

In hydraulic and pneumatic systems there exists a component called a “check valve”. The “check valve” is used to direct the flow in one direction only.

Does this “check valve” exist in an electrical system? If so, what is it called?

If a guy wanted to do his own R&D, (tinker and experiment) for educational purposes, would one of these “electrical check valves” work to change a 12v electric motor into a 12v electric generator?

How would this be done?

Sorry if my questions are somewhat elementary, but I am a mechanic, not an electrician. All I know about electricity is that in terms of running wires it is much like plumbing. Here are some things I think I understand, please feel free to correct and clarify….

In hydraulic terms….
Volts = flow?
Amps = pressure?
HP or horse power is the measure of how much work can be done in a given amount of time. Does this equate to watts? Therefore…
KWH = HP?

Thanks very much for your time and
Have a GREAT DAY!!!
Gene

[Rob Beckers]

Hi Gene,

The equivalent of a check valve in electrical terms is a diode. It only allows electrical flow in one direction. Unfortunately it won't turn a motor into a generator (at least not that I can see).

As to the others:

Volt = pressure
Amp = flow
746 Watt = 1 HP

kWh does not equate to HP; one is energy, the other is a measure of power. Energy is power over time (ie. Watt is power, multiply by time in hours and you get Watt-hours or Wh, this is energy, divide by 1000 and you have kWh, another energy measure).

-RoB-

[Gene Sp]

Hey RoB

Thanks for the response.
This site http://www.physclips.unsw.edu.au/jw/electricmotors.html#mandg explains that a motor and gereator are the same. In hydraulics, a motor or generator are EXACTLY the same. The only thing that determines wheather it is a pump or a motor is which end is driven. If the shaft is driven on a hyraulic unit, it is a pump that pushes fluid to do work. On the other hand, if the fluid is pushed into it to cause the shaft to turn and therefore do the work, it is then a motor. Internally they are the sane.

Therefore, my question is, how does an electric generator differ from an electric motor? The same components are in each. But without some other components to stop the flow of electricity in one direction, a diode, if I were spinning a motor via the shaft creating electricity, as soon as I hooked it to a battery in order to charge the battery, (just an example) the battery would transform the "generator" into a "motor".
OR why won't a motor that is driven by it's shaft create electricity??

Thanks again for your time and
Have a GREAT DAY!!!
Gene

[Stewart Corman]

a few simple answers


Therefore, my question is, how does an electric generator differ from an electric motor? The same components are in each.yes, as long as you are talking a PM motor ..if it has field windings, then no

if I were spinning a motor via the shaft creating electricity, as soon as I hooked it to a battery in order to charge the battery, (just an example) the battery would transform the "generator" into a "motor".almost ...electricity flows from a higher potential to a lower potential (reads voltage) ...so as long as the created voltage is higher than the battery being charged, the juice flows to the battery ...if you have a wind turbine that has no wind, yes, the battery will turn the rotor backwards as a motor..that is why they use a blocking diode for a DC generator ( an AC servo motor a diode is irrelevant here)

why won't a motor that is driven by it's shaft create electricity??


it will, just connect it to a resistive load ...whenever it turns, it will produce electric current ...batteries make it complicated

Stew

[Dave Turpin]

a few simple answers

yes, as long as you are talking a PM motor ..if it has field windings, then no.

Stew

Not really true. The field windings just have to be excited so that a magnetic field exists. Pretty much only induction motors do not work as generators. An alternator is wired exactly the same as a synchronous motor.