Hipot testing

[norse]

I am looking for a way of checking for good connections in a system where an insulated wire is put into a water bath for hipot testing.
At present, I only know that I have voltage going into the wire if the wire is bad, creating a ground loop through the water. How can I measure if I have a voltage potential in the wire if there is no failure?

 

[melone]

Would a simple continuity check work?

 

[norse]

I have only the connector end available, the other end of the wire is insulated ans submerged.

 

[SteveKW]

A voltmeter is used to measure "potential". Can you elaborate a little more as to what you are trying to do?

 

[melone]

It sounds like the only thing that you can do is monitor the voltage & current going into the wire. If the voltage ever drops and the current rises, then you have a short to ground (via the impurities in the water). Otherwise, you should be able to assume a good wire.

What exactly is the submerged wire? Why would you want to create put a potentially dangerous situation like this? It sounds like you are doing some sort of insulation testing, but without a little more information, it is difficult to say.

If you are testing the insulation, why do you need to submerge the wire? Is this for some enviornmental restrictions on the wire?

Please keep us posted!

 

[norse]

the process is an insulation test in saline solution for medical guide wire. We are using a Vitrek V51 ac/dc safety analyzer to put a 100 Volt load on a wire and checking for current leakage. A good wire has a max current of 10 mA. Most wires read 0.00 mA, (due to sensitivity of read out?). Won't there always be some level of current leakage?

 

[melone]

Yes, but to see the amount of current you would need more than .00 mA sensitivity on your meter. If you are worried about having a continuous wire from connector end to the end of the insulation, why don't you try using some sort of RF testing. If the length of the wire is fixed, then there will be some set of frequencies at which the wire will be an efficient transmitter/reciever. If for some reason the wire is shorter (b/c it is broken), then the amplitude of the recieved/transmitted signal should decrease. [I am just brainstorming here].

Once you figure out the corresponding frequencies based on the length of wire, then you can create a small transmitter that will connect to the connector end of your wire. Set up a reciever circuit at some fixed distance away, and have the circuit sounds a buzzer if the recieved amplitude exceeds a specified limit. This should allow you to quickly and somewhat repeatedly test wire continuity. [I think!!!!]

Maybe some of the others with a little more knowledge can let me know if my theory is at least correct!

Keep us posted!

 

[230842]

First of all,I think that a 10 mA leakage current for 100 V hipot test voltage is a extremely high current value for a good wire intended for general purposes and unacceptable for medical aplications. Modern insulating materials may give currents of some micro or nano amperes. This could be the reason why you have a lack of readout sensitivity.
If you want to be sure whether you are correctly testing or your test equipment does not work, I suggest you to connect a digital voltmeter between output and guard connection, if there exist, and check for the voltage presence.
Other alternative: Test a "bad" wire and check the test equipment response. There are several easy ways to get a "bad" wire. Julian

 

[ccaserta]

I would try using a ground continuity tester. This is will allow you to send 25 to 30 amps throught the chassis and water and test the insulation between the conductor and ground including the water. "Sorry for the late reply" Christopher Caserta
Sr. Regulatory Engineer
ccaserta@enorthhampton.com
Ph:904-225-0360
Fax:904-225-0340

 

[jmarko]

One way of measuring lenghth of imersed wire is to measure capacitance between water as one pole and wire as other pole.