How would you sense the current direction in an AC circuit loop?
Possibly control some SCR or triac when the current is flowing in the wrong direction.

 

What's the wrong current direction in an AC circuit?

 

First of all, how is this "AC diode" supposed to behave?

 

I think that the direction of instantaneous current flow can be observed on the output of a simple current transformer.

Your question contains some ambiguity. Do you mean for it to ask how to determine the direction of power flow in an AC circuit?

 

What is the frequency range? If it is RF, maybe try a directional coupler?

 

First of all, how is this "AC diode" supposed to behave?

Take a point contact diode and pass enough current to blow the whisker............................

 

How would you sense the current direction in an AC circuit loop?
when the current is flowing in the wrong direction.

I have always been under the impression that the A in AC means Alternating, as in direction!
Max.

 

I have always been under the impression that the A in AC means Alternating, as in direction!
Max.

There are a few weird and wonderful "diodes" that do different things than rectify AC.

A diac or similar 4-layer device might be what the TS is trying to find.

 

How would you sense the current direction in an AC circuit loop?
Possibly control some SCR or triac when the current is flowing in the wrong direction.

The most practical method I know of is to use a combination of simultaneous current and voltage comparative monitoring to determine the direction of power flow to switch the power on on and off to whatever you want blocked via a relay or some other switching device.

In the old days it was done with a dual coil electro mechanical device that worked on the same principle as a common spinning disk utility meter works but in today's solid state systems it can all be done with Op-Amp comparators and Solid State power devices in near cycle by cycle time and speed.


The bigger question is what do you need such a device for?

 

What is the frequency range? If it is RF, maybe try a directional coupler?

60 hz

 

What's the wrong current direction in an AC circuit?

The direction that forces it into a generator.

 

The most practical method I know of is to use a combination of simultaneous current and voltage comparative monitoring to determine the direction of power flow to switch the power on on and off to whatever you want blocked via a relay or some other switching device.

In the old days it was done with a dual coil electro mechanical device that worked on the same principle as a common spinning disk utility meter works but in today's solid state systems it can all be done with Op-Amp comparators and Solid State power devices in near cycle by cycle time and speed.



The bigger question is what do you need such a device for?

I want to attempt to connect both a back-up generator and a micro-hydro generator via grid tie inverter to the load side of the transfer switch without damaging the backup generator or the inverter. I was thinking about controlling a IGBT H-bridge from the inverter that would augment the BG when the impedance fell below a certain threshold or stifle the output when the BG could handle the load without engaging the load controls.

BTW, Thank you for your helpful input.

 

I have always been under the impression that the A in AC means Alternating, as in direction!
Max.

You are correct the Voltage does alternate but the current flows in one direction yet I am sure I am in for a debate.

 

I think that the direction of instantaneous current flow can be observed on the output of a simple current transformer.

Your question contains dome ambiguity. Do you mean for it to ask how to determine the direction of power flow in an AC circuit?

yes the power flow.

 

You are correct the Voltage does alternate but the current flows in one direction.

Are you sure about that?

 

I want to attempt to connect both a back-up generator and a micro-hydro generator via grid tie inverter to the load side of the transfer switch without damaging the backup generator or the inverter. I was thinking about controlling a IGBT H-bridge from the inverter that would augment the BG when the impedance fell below a certain threshold or stifle the output when the BG could handle the load without engaging the load controls.

BTW, Thank you for your helpful input.

The grid tie inverter will handle the power feedback as it needs to, it's what they do by design. As for the generator there is no easy and practical way to direct connect a common genset to a utility line unless you have a very solid background in AC power system theory and actual device design and operation. It's not something you just plug in and go to back feed with.

I've been building Grid Tie Inverters for years and have never written a number of basic DIY tutorial thread on designing and building one. Even as thoroughly distilled as I have so far the DIY info on the subject it's still a fairly mid to upper level electronics project to build one.

My threads on GTI design and construction found here. https://www.electro-tech-online.com/forums/alternative-energy

It's way more complex than just monitoring impedance or inductance or anything else to do live line power feedback. On a very basic and limited power level (sub kilowatt power inputs) is not terribly difficult to do variable DC to AC power feedback with simple common components but it gets more complicated as the power level go up.

 

You may determine the direction of current by it's magnetic pole. Current has handedness.

 

The direction that forces it into a generator.

You are correct the Voltage does alternate but the current flows in one direction yet I am sure I am in for a debate.

I think you have a basic misunderstanding of electrical energy and how it works in DC or AC circuits.

I want to attempt to connect both a back-up generator and a micro-hydro generator via grid tie inverter to the load side of the transfer switch without damaging the backup generator or the inverter. I was thinking about controlling a IGBT H-bridge from the inverter that would augment the BG when the impedance fell below a certain threshold or stifle the output when the BG could handle the load without engaging the load controls.

BTW, Thank you for your helpful input.

To parallel your AC power sources you need to synchronize the frequency, phase and voltages of the AC outputs to the power grid. This is hard to do with equipment not designed for it. Not happening with a H-bridge or a 'AC diode'. It's much easier to combine DC sources into a common inverter power feed.

https://en.wikipedia.org/wiki/Synchronization_(alternating_current)

There are five conditions that must be met before the synchronization process takes place. The source (generator or sub-network) must have equal line voltage, frequency, phase sequence, phase angle, and waveform to that of the system to which it is being synchronized.[1]

The grid won't change so you must have your system in almost exact sync for it to work.

 

The grid won't change so you must have your system in almost exact sync for it to work.

Yep, and with some portable single phase generator designs (newer passive synchronous rotor type, I think) they are near impossible to keep locked in phase if there is any degree of engine stumbling or line side voltage and or frequency fluctuations.

If they lose their synchronization they tend to go nuts in the worst way until disconnected from the line.

 

Voltage does alternate but the current flows in one direction yet I am sure I am in for a debate.

??????
Max.