Static electricity measure 1

[ManuOrb]

Good morning, we're a valves manufacturer company. A client has asked us to measure the static electricity in our valves to assure no problems in hazardous areas.
According EN-12266 we should open and close five times the valve and then measure the resistance between the obturator and the body with a 12 V potential and a 100 V potential and verify it's under 10 ohm.
Now here comes (I'm not very good at electrics).
First we measured the resistance with a tester (3V) and it gives about 0,3 ohm.
Then we used a 12 V potential and made a small circuit:
- From 12 V source to obturator. Then we touched the body with the tester and the other side of the tester to the 12 V source. We measured the current: 0,64 A. Then resistance = 18,75 ohm.

- We repeat the same with a 48 V source (that's what we have here) and we measured 8 A. So resistance = 6 ohm.

Now, I'm completely confused. Any ideas?

Thanks in advance.

 

[sendelkr]

ManuOrb
i have just refered the Std API 609 where these lines where mentioned for testing the electrical continuity ....

When specified in the purchase order, valves shall incorporate
an electrostatic feature that ensures electrical continuity
between the shaft and the body or the shaft, body, and disc.
The valve shall have electrical continuiaty across the discharge
path, with a resistance of not more than 10 ohms. To test for
continuity, a new dry valve shall be cycled at least five times,
and the resistance shall be measured using a DC power
source not exceeding 12 volts.

So it states that the Potential across shouldnt exceed 12V ..now iam bit confused ..

sendel kumar

 

[svi]

Each of the sources have their internal resistances. Also the volt meter should have a high internal resistance so that only very small current flows through it without causing a further voltage when touching across the valve contacts. If you do a google search on this, should be able to find, how to go about doing this.