WIGGY Input Impedance
- Thread starter dereckbc
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racerdave3
Senior Member
- Location
- Western Massachusetts
dereckbc said:
Good question that I don't have the answer to, although I wouldn't suspect it to be all that much. You could plug the Wiggy in to test a receptacle then put a clamp on amp meter on one of the leads and see what it reads.
360Youth
Senior Member
- Location
- Newport, NC
racerdave3 said:
Wow! I don't know if you read my mind or I read your post.:grin:
I always liked using the recptacle adapter for reading curent through an appliance. It plugs into the recept. and is formed to clamp around and has a recept built into the end. Nice for not having to remove device just to draw an amp reading.
- Location
- Massachusetts
dereckbc said:
For a meter it draws quite a bit even at 120 volt.
I will try to test mine when I get a chance, at 480 it draws a pretty good spark.
I would measure guys, but I am an engineer and do not own a WIGGY. I have lots of other toys, just no WIGGY. They are cheap enough, so I can't use that excuse.
Just curious from reading in another post that WIGGY can damage some circuits. Input impedance has to be the answer.
Just curious from reading in another post that WIGGY can damage some circuits. Input impedance has to be the answer.
- Location
- Illinois
- Occupation
- retired electrician
I know that it is less than 30mA at 120 volts because it won't trip the GFPs that I use for heat trace protection.
Don
Don
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Of course, it does; it's an inductor.iwire said:
- Location
- Massachusetts
LarryFine said:
To be honest Larry I do not know what that really means.
All I know is it is a coil and has a large inrush current.
Is that what an inductor is?
tallgirl
Senior Member
- Location
- Glendale, WI
- Occupation
- Controls Systems firmware engineer
iwire said:
More or less.
An inductor is, generally speaking, anything that stores electrical energy in the magnetic field created around the inductor. A capacitor, on the other hand, stores energy in the electrical field between the two insultated conductors in the capacitor.
What happens with an inductor at the time the circuit is opened is the magnetic field in the inductor begins to collapse. This induces a current in the inductor, and that current has some voltage (I think this is Faraday's Law -- one of the EE's here can check me). If the induced voltage is high enough, arcing can occur. This, conveniently, is the basic principle behind the "breaker-point ignition" from when we were all kids.
In the case of the wiggy, energy is stored in the solenoid in the magnetic field which is surrounding it and which makes the plunger move to indicate voltage. When the test lead is removed from the test point, that magnetic field is no longer being maintained by current flowing through the conductors in the wiggy, it begins to collapse, thereby creating a voltage (E = dΦ/dt -- voltage is the change in magnetic flux with respect to time (the weird letter is "Phi", for anyone who cares))
What's needed, I'd think, is to replace the simple inductor in the wiggy with an RLC circuit with the solenoid being the inductor (L term), a capacitor to absorb the energy from the collapsing field (the C term) and a resistor to drain the energy stored in the L-C network (the R term).
- Location
- Massachusetts
Some test results.
Using my Fluke 87 DMM in series with a 120 volt circuit supplying an Ideal 61-065 Solenoid tester.
To read the 120 circuit the solenoid tester used 25.42 ma.
For the heck of it I tried the same thing with my Simpson 260.
To read the 120 volt circuit the Simpson 260 was fairly steady at 00.11 ma.
Jumping from 120 to 240 volts resulted in the following
The Solenoid tester required 52.8 ma
The Simpson 260 required 00.19 ma
I don't have 480 here at the house unless I backfeed a control transfomer.....
Using my Fluke 87 DMM in series with a 120 volt circuit supplying an Ideal 61-065 Solenoid tester.
To read the 120 circuit the solenoid tester used 25.42 ma.
For the heck of it I tried the same thing with my Simpson 260.
To read the 120 volt circuit the Simpson 260 was fairly steady at 00.11 ma.
Jumping from 120 to 240 volts resulted in the following
The Solenoid tester required 52.8 ma
The Simpson 260 required 00.19 ma
I don't have 480 here at the house unless I backfeed a control transfomer.....
tallgirl
Senior Member
- Location
- Glendale, WI
- Occupation
- Controls Systems firmware engineer
iwire said:
When do you expect to have those test results for us? :grin:
What would be interesting is to put a storage scope across one of the test leads and whatever you're testing and measure the voltage spike when you remove that lead. I'm guessing the voltage exceeds 1kV, and judging from the size of spark, assuming I read you correctly, I wouldn't be surprised if the voltage exceeds 10kV.
- Location
- Massachusetts
tallgirl said:
Not sure where the control trans is located, it could be out in the unheated garage.....meanaing I ain't going out.
I have a BK Precision 2120 scope, to be honest I really don't know how to use it, I also have (or maybe had) a storage unit that went with it. I think the storage unit went out during a clean up of the basement.
tallgirl
Senior Member
- Location
- Glendale, WI
- Occupation
- Controls Systems firmware engineer
iwire said:
Darn. Science has been thwarted again.
I have a BK Precision 2120 scope, to be honest I really don't know how to use it, I also have (or maybe had) a storage unit that went with it. I think the storage unit went out during a clean up of the basement.
If you fly me up there I'm sure I could figure out how to conduct this phase of our testing. Tell your boss it's "Very important safety testing."
The short answer is that you should have a high voltage probe of the kind that was typically used to diagnose CRTs that you'd have to connect to the lead on the wiggy. The other probe of the scope goes to the AC circuit you're testing. Set the scale on the meter to the appropriate level (I'd start at the top of the range for the scope), then see if the meter has an adjustable trigger you can set. Set the trigger high enough that it won't catch the 120 or 240v that will be present when the wiggy's lead isn't touching the 120 or 240v circuit, then see what shows up.
- Location
- Illinois
- Occupation
- retired electrician
Julie,
Don
A lot of old time electricians like me found out about that when using a flashlight continunity tester to test transformer windings...if you were touching the transformer leads when you disconnected the tester, you got bit.
Don
tallgirl
Senior Member
- Location
- Glendale, WI
- Occupation
- Controls Systems firmware engineer
don_resqcapt19 said:
I think I found out when I was 8 years old
I forget how I found this out, but I was into a lot of things as a child. How I survived to adulthood is a miracle!I am surprised that wiggys don't have something built in to suppress the arc. Mine, which was a gift from an electrician in New Orleans, is a bit fried. If I ever get around to replacing it I'll open it up and see what the heck is actually inside one and if there is some way to suppress the arc with a big, fat capacitor and a resistor.
growler
Senior Member
- Location
- Atlanta,GA
tallgirl said:
Ideal makes a better version with Arc protection. Probably cost a few dollars more. I haven't used a wiggy in years.
That would dampen the movement and prevent it from vibrating a key feature electricians look for.tallgirl said:
There is nothing to a WIGGY. It is just a solenoid connected to a spring with a calibrated pointer/indicator. The higher the voltage, the more deflection in the movement.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
One can also use a simple bulb as a load when measuring voltage. Even a night-light bulb will load a circuit enough to minimize false measurements due to inductive coupling.
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