mains supply or generator supply?

[mailus]

I am in need to design a circuit that must detect the supply type(mains or generator) by using a wall socket.
yes the supply is to be detected by using two wires (phase and neutral).if supply is generator means i want to glow a LED.
any ideas to design this circuit.

(by using a controller or analog electronics or digital electronics)

 

[Nigel Goodwin]

To detect the difference you have to know what the difference is, so what is the difference between your two supplies that you could look for?.

Most likely scenario would probably be the accuracy of the frequency?, although that probably depends how poor your mains supply is anyway.

 

[ADWSystems]

It also depends on how good the generator is. If you have a high-end sinewave output generator, it may be difficult to detect. If you have a low end, square wave output model, then you know what you are looking for. Some of the mid range model have a chopper stabilized sine wave, on those you could look for the periodic drop outs.

Direct detection based on the line voltage condition itself maybe difficult. Another option would be to inject a signal/frequency onto the power line within the house (communication/Ethernet over power type of thing like https://www.amazon.com/TRENDnet-Com...id=1378316637&sr=8-1&keywords=trendnet+500mps). When running on the mains inject the signal (detect main versus generator based on a relay/sensor attached to the main line or generator). The detector would sense that frequency on the line and turn the LED off in on mains, or lack of frequency on the line when running from the generator and turn the LED on.

Hopefully you can follow that. The concept is there, but the experts will need to chime in on how to make the transmitter and detector modules.

 

[Nigel Goodwin]

It also depends on how good the generator is. If you have a high-end sinewave output generator, it may be difficult to detect. If you have a low end, square wave output model, then you know what you are looking for.

I presume you're assuming an inverter?, rather than a generator - a motor driven generator would provide a fairly decent sinewave, which was why I suggested checking the frequency which will vary some what with load.

 

[ADWSystems]

All generators have some type of "regulator" on them. True, they normally produce a decent sinewave, but the voltage and frequency varies with motor RPM, and with the RPM is dependent on the load as the load changed (fridge turning on/off) the voltage and frequency would change. Some "regulators" are better than others. I spent many months comparing quality and price prior to purchasing my generator. I have a mid-range portable generator with the chopper style output . Very good for motor loads and more robust electronics (furnaces and coffee makers) but not so good for higher end electronics such as computers and TVs. This unit cost me $1200 (US). The inverter sinewave output models started at $3600. Very much overkill (and somewhat susceptible to damage) for motor loads such as well pumps and refrigerators, but great for electronics and computers.

As you said, to know what difference you are looking for you need to know what the difference is. As his location is not listed, it is hard to guess on the quality of the utility power. Comparing the quality of the line power versus generator power here in the US, would provide too many variables for me to try to differentiate between directly based only on what a circuit or oscilloscope could tell me.

 

[Nigel Goodwin]

As you said, to know what difference you are looking for you need to know what the difference is. As his location is not listed, it is hard to guess on the quality of the utility power.

As he's talking about generators I presume utility reliability is low?, so quality is likely to be poor as well - most of these kind of posts come from Africa or India.

 

[jpanhalt]

This is another one of those questions where it is hard to guess, "why do it that way." A dual supply system (i.e., generator and mains) should have an isolation switch between them. Why not monitor that switch or whether the generator is running?

Alternatively, if there is a need to monitor at the outlet, I wonder whether a low-level, high-frequency signal could be injected at the generator or switch. That could easily be detected at outlets to give the "LED" signal the OP wants. In fact, the signal could be encoded to show when alternative power was switched on or any other important information.

John

 

[ADWSystems]

This is another one of those questions where it is hard to guess, "why do it that way." A dual supply system (i.e., generator and mains) should have an isolation switch between them. Why not monitor that switch or whether the generator is running?

Alternatively, if there is a need to monitor at the outlet, I wonder whether a low-level, high-frequency signal could be injected at the generator or switch. That could easily be detected at outlets to give the "LED" signal the OP wants. In fact, the signal could be encoded to show when alternative power was switched on or any other important information.

John

Using my house as an example, monitoring and indicating at the switch would not be very visible, the switch is downstairs and I know some (my neighbor for example) where the switch is outside. At the outlet would provide an indicate within the living space or somewhere you could readily see it.

The second part is similar to the philosophy I tried to state. Hopefully it is clearer than mine.

 

[mailus]

I wonder whether a low-level, high-frequency signal could be injected at the generator or switch.
John

give me some ideas about this method.....

 

[jpanhalt]

Search on "power line network" and "power line control/communication." Here are two descriptions:

https://computer.howstuffworks.com/power-network.htm
https://en.wikipedia.org/wiki/Power_line_communication

There are many off-the shelf items for implementing it. One currently available application of power line control (PLC) is home lighting. Consider this scenario: Every light in the home or office gets wired with just a power (black), neutral (white), and (maybe) ground (using USA nomenclature). There is no switched wire, but the fixture is designed with an electronic switch. At the control units (i.e, wall switches), the user programs which light in the house will be operated by which switch. For example, you could have a switch in the bedroom operate the front door light. Communication is over the power line. I came across a commercial vendor of such a system a few months ago -- it may have been Cooper, but I don't remember the name of it right now.

I think such a commercial system might easily be adapted to your purpose. I am sure you will also find some DIY implementations in your search.

John

 

[Nigel Goodwin]

Or why not just two wires from the generator to a simple bulb where you want a display of the generator running?.

 

[mailus]

Or why not just two wires from the generator to a simple bulb where you want a display of the generator running?.

it is needed for an apartment. no way to change the wiring or any changes in the electrical network.

 

[Nigel Goodwin]

it is needed for an apartment. no way to change the wiring or any changes in the electrical network.

Wireless transmitter at the generator then, and a receiver and indicator at the apartment - unless you have some way of distinguishing the difference between mains and generator?.

 

[ADWSystems]

it is needed for an apartment. no way to change the wiring or any changes in the electrical network.

Back to the first option then. You will need to evaluate the AC waveforms with a scope from both the generator and from the utility and determine if you can see a difference. If you can see a difference and can relay that information to the forum, then we can help build a circuit that can tell the difference.

 

[alec_t]

Baby call monitor close to generator, plus receiver in apartment?

 

[mailus]

Back to the first option then. You will need to evaluate the AC waveforms with a scope from both the generator and from the utility and determine if you can see a difference. If you can see a difference and can relay that information to the forum, then we can help build a circuit that can tell the difference.

sorry, i don't have a oscilloscope.i will try to find the difference.

 

[Ramussons]

it is needed for an apartment. no way to change the wiring or any changes in the electrical network.

That seems to rule out any modification / attachment to the generator.

alec_t seems about the best option.

Ramesh

 

[samovar]

Back to the first option then. You will need to evaluate the AC waveforms with a scope from both the generator and from the utility and determine if you can see a difference. If you can see a difference and can relay that information to the forum, then we can help build a circuit that can tell the difference.

Since the voltage drops in the wiring between the source and the outlet depending on current, which will not be in sync with voltage (for most loads), the waveform at the outlet will appear distorted compared to the waveform at the source. The only thing to rely on is the frequency.

 

[ADWSystems]

Since the voltage drops in the wiring between the source and the outlet depending on current, which will not be in sync with voltage (for most loads), the waveform at the outlet will appear distorted compared to the waveform at the source. The only thing to rely on is the frequency.

Both frequency and voltage will vary from both the utility and the generator. We can't depend solely on either. If you plug this magic thing we're helping design into an outlet with no load on it, there would be no voltage drop/change. Therefore we wouldn't have to worry about this. Even if one thought about worrying about it, the amount of voltage drop incurred would be within the noise of the inherent variations and fluctuations of the voltage source.

We don't know how good the waveform is from his utility. We have some information on possible outputs from the generator. There are three major types of regulators, and we know the effect of adding and removing loads to the generator and how any load applied or removed effects the voltage and frequency.

Since we can't "modify" the incoming power feed (ie., inject a signal), and until we can get more information about the power quality from both sources, I'm not sure if we can go any further.

 

[alec_t]

If the OP is in an apartment and has no control over the supply, be it from the utility or generator, what good does knowing the supply source do? Suppose the OP wants to unplug some susceptible consumer devices if the generator is in use, because (for argument's sake) the gen puts out damaging square waves. By the time the magic monitor has detected 'generator running' any damage is probably already done