voltage phase tester

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If what you describe is what you want- then all you want is a differential voltage above some allowable minimum. The phase won't matter. When you use a conventional voltmeter between two wires- whether true rms or Radio Shack special (average+bugger factor) this is what you are doing. If the two points are at the same potential at any and all instants, such a meter will indicate it. If not- than that will be indicated. A simple detector will do this. Phase measurements are not needed. Part of the problem with a capacitive pickup device is that , as far as I know, even expensive devices (substation capacitive votlage devices) are not suited to accurate phase measurements without compensation and a fixed location with respect to the hot wire.

It may be possible, for 3 phase applications to set up a unit which can detect phase rotation but accurate phase measurement in a portable device with no actual contact..?

| If what you describe is what you want- then all you want is a differential | voltage above some allowable minimum. The phase won't matter. When you use a | conventional voltmeter between two wires- whether true rms or Radio Shack | special (average+bugger factor) this is what you are doing. If the two | points are at the same potential at any and all instants, such a meter will | indicate it. If not- than that will be indicated. A simple detector will do | this. Phase measurements are not needed. Part of the problem with a | capacitive pickup device is that , as far as I know, even expensive devices | (substation capacitive votlage devices) are not suited to accurate phase | measurements without compensation and a fixed location with respect to the | hot wire. | | It may be possible, for 3 phase applications to set up a unit which can | detect phase rotation but accurate phase measurement in a portable device | with no actual contact..?

I'm not trying to accomplish accurate; I'm trying to accomplish verification that phasing is correct after energization, and phase identification when working on hot wires, without having to come in contact with the wires. Plus or minus 30 degrees would probably do it, though it if were within 10 degrees I think there would be more confidence.

You wanna stick the probes of your Radio Shack voltmeter on live 12470 volt wires?

Phase identification could not be achieved on the basis described because the frequency drifts. In UK the frequency limit is + or - 0.1 Hz. That is 1 hz in

I have determined phase using a simple capacitative coupler but needed a radio link back to a master freq reference signal. It works really well. I have done it over a distance of 50 km.

Robin Watson

| Phase identification could not be achieved on the basis described because the | frequency drifts. In UK the frequency limit is + or - 0.1 Hz. That is 1 hz in | 500 hz which is only 10 seconds. Thats a max slip from true 50hz of 360 degrees | in 10 seconds. | | I have determined phase using a simple capacitative coupler but needed a radio | link back to a master freq reference signal. It works really well. I have done | it over a distance of 50 km.

So looking at two (one being a known) phases at once would be required. OK, so I'll bury the idea.

differential

verification

----------- I got nervous when, during a light snowstorm, I saw winking from part way down an post insulator in a 735KV substation. it makes one want to check relative distances- to ground and to me..

I wouldn't want to be anywhere near with a RS meter. With proper meters and equipment- fine- but I really would prefer to put in a PT or properly designed capacitive voltage divider (inserting it dead- Thank you.) However- such capacitive devices in a portable situation may be questionable and not to be trusted except for indication of potential. However, I have been wrong before. Does the device you mention have compensation circuitry? If so it may be within the phase angle range that you indicate. If you can get a couple of such devices and apply them to a known line and compare the voltages on a 2 channel scope, you would have something to go on and could see the effects of variations of distances from the line or non-contact devices.

Don't bury it yet- if the two phases are in the same system, frequency shifts within normal bounds are not that important- relative phase is what you are looking for . How expensive a circuit would be to detect this is another problem but may not be all that great.