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Author Topic: Pulsed Current Tester  (Read 2937 times)

Mike Sokol

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Pulsed Current Tester
« on: March 20, 2014, 02:04:52 am »

Mike gave a great idea for IDing a circuit without turning it off in another thread.

I just found this yesterday from an eBay seller in China where I've bought a few panel meters and such. This is a two-channel 120-volt timer relay that should be configurable to turn it into a basic 1-second on/off oscillator. As you mentioned, I wrote in another thread about using a TD relay to turn a 4 or 5 amp load on and off to make a current that's traceable in a live panel with other currents active. Of course you'll want to take all arc-flash and shock precautions in any live panel. But at least this is a good way to create an easily traceable current path. Here's the eBay link to the relay, which cost $14.69 including FREE shipping from China to USA. Takes about 2 weeks to arrive, so order early if you want to give this a try: http://www.ebay.com/itm/110V-AC-Programmable-Double-Time-Delay-Relay-ATDV-Y-/390343084469?pt=LH_DefaultDomain_0&hash=item5ae242c9b5



 
« Last Edit: March 20, 2014, 04:01:53 pm by Mike Sokol »
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Mike Sokol
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Frank DeWitt

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Re: Pulsed Current Tester
« Reply #1 on: March 21, 2014, 08:30:50 pm »

I just found this yesterday from an eBay seller in China where I've bought a few panel meters and such. This is a two-channel 120-volt timer relay that should be configurable to turn it into a basic 1-second on/off oscillator.

I couldn't figure out for sure if it will self cycle but I did find this
http://www.ebay.com/itm/110v-Digital-time-delay-repeat-cycle-relay-timer-1s-990h-LED-display-8-pin-panel-/221250567088?pt=US_Rear_View_Monitors_Cams_Kits&hash=item33838fbbb0

Here is the paper work
http://www.sah.rs/Brojaci%20I%20Tajmeri/Manual/DH48S-S.PDF

Also, for a bit more work (A wall wart and a box) there is this.  http://www.ebay.com/itm/Multifunction-Self-lock-Relay-Cycle-Timer-Module-PLC-Home-Automation-Delay-12V-/271411932106?pt=LH_DefaultDomain_0&hash=item3f31696bca
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Mike Sokol

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Re: Pulsed Current Tester
« Reply #2 on: March 21, 2014, 09:11:09 pm »

I couldn't figure out for sure if it will self cycle but I did find this
http://www.ebay.com/itm/110v-Digital-time-delay-repeat-cycle-relay-timer-1s-990h-LED-display-8-pin-panel-/221250567088?pt=US_Rear_View_Monitors_Cams_Kits&hash=item33838fbbb0


Yup, this should do the trick. Note that it only has 3-amp contacts, so you should limit your test load to 200 or 300 watts. If you want more of a load, then you should connect it to a heavy-duty relay of some sort. But a pair of 100-watt light bulbs (incandescent) would give you a periodic 1.7 amp current that should be easy to find within a bunch of other loads.
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Stephen Swaffer

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Re: Pulsed Current Tester
« Reply #3 on: March 21, 2014, 10:57:11 pm »

But a pair of 100-watt light bulbs (incandescent) would give you a periodic 1.7 amp current that should be easy to find within a bunch of other loads.

Until your helper plugs in his pulsating load set at a slightly different time into another circuit-or even better into the same circuit-either without thinking or just to mess with your mind :)!
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Mike Sokol

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Re: Pulsed Current Tester
« Reply #4 on: March 22, 2014, 01:31:15 am »

Until your helper plugs in his pulsating load set at a slightly different time into another circuit-or even better into the same circuit-either without thinking or just to mess with your mind :)!

Yup, that could make you crazy.  ::)

However, this is simple troubleshooting technique for sorting out swapped neutrals. It's pretty easy to see the periodic pulsed current in the middle of a bunch of other static and randomly changing currents.
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Mike Sokol
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Mike Sokol

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Re: Pulsed Current Tester
« Reply #5 on: March 22, 2014, 01:47:51 am »

Quote
Quote from: Stephen Swaffer on March 19, 2014, 11:32:07 pm

    Mike gave a great idea for IDing a circuit without turning it off in another thread.

I think I remember posting in a thread somewhere about building and using a pulsed current tester with a coffee pot load to trace a floated neutral short circuit, but my mind must be going since I can't find it. Does anybody remember where that is?
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Tommy Peel

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Re: Pulsed Current Tester
« Reply #6 on: March 22, 2014, 02:31:12 am »

I think I remember posting in a thread somewhere about building and using a pulsed current tester with a coffee pot load to trace a floated neutral short circuit, but my mind must be going since I can't find it. Does anybody remember where that is?
I think this is the missing thread Mike: http://forums.prosoundweb.com/index.php?topic=148095.0

I think it's on page 2 on my phone.

P. S. Really enjoy reading the threads in this forum. Lots of good information.

Sent from my Nexus 4 running OmniROM 4.4 KitKat using Tapatalk Pro

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Mike Sokol

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Re: Pulsed Current Tester
« Reply #7 on: March 22, 2014, 07:54:02 am »

I think this is the missing thread Mike: http://forums.prosoundweb.com/index.php?topic=148095.0


Yup, that's it. Here's the text of that thread. In addition to tracing circuit breakers, this pulsed current technique can also help you sort out neutrals which have been swapped or wired to the wrong panel. A neutral in the wrong place can cause GFCI sensors to randomly trip.

Once upon a time, in a land far away (not really, but a good opener) I built a 10-amp pulsing load from a pair of time-delay relays and a coffee pot. Since it pulsed about once per second, I was able to easily trace where that special "pulsed" current was going right in the middle of stationary loads using nothing more than an analog clamp ammeter. So, if you could get inside the panel with a clamp-meter on each circuit breaker, then plug the pulsing load into each outlet, you could easily determine if that breaker was feeding that particular outlet. Nothing needs to be shut down, and this would be 100% accurate.

If you can't get inside the live box (don't do it unless you're qualified and take proper Arc Flash precautions) you could do a secondary (but not 100% accurate test) by simply applying the pulsing load to a single outlet, then checking all other outlets for a pulsing voltage drop. I don't consider this to be 100% accurate since there could be some voltage drop in the sub-panel reflected to all other branch circuits. But I think with a little interpretation you could easily figure it out measuring the pulsing voltage drop in the various outlets.
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