Flow switch triggers off at high voltages

[Tharosa Rajaratne]

Hello,

I have a High Voltage System (which operates an XPS system) in which I replaced the flow switch recently. The previous flow switch was a Henke Sass Wolf DW-P, configured as Normally open. The new flow switch is a Proteus 100C (24VDC) which was also configured as normally open. The trigger is set at 3.0 L/m.

The problem is when I ramp up the High voltage system to about 8 kV, the flow switch triggers itself off and causes the HVS to revert the voltage down to zero. I checked if the water flow is disturbed, but there was no indication of that.

I am somewhat confused as to why this happens and I am unable to find a proper reason. I would much appreciate it if someone can explain what could be the reason.

Thanks in advance!

[Rich Feldman]

Thanks for identifying your flow switch. Datasheet was easy to find. https://proteusind.com/wp-content/uploa ... 100TRM.pdf
I have something like that from flea market years ago, but never paid attention to its electrical behavior.

You mention no indication that water flow is disturbed. Can you confirm that the flow switch rotor keeps turning?

We might guess that when your power supply or associated XPS apparatus gets up to 8 kV,
something interferes with the magnet-motion-sensing electronics inside flow switch.
Experimental remedies might include moving or shielding the flow switch, or putting it on battery power.

Datasheet section 4 says
"To configure a 0100xxxx model for a flow range of 1.9–9.5 LPM / 0.5–2.5 GPM, it is necessary to
reverse the connections to the induction coil for proper operation of the flow switch."

[Tharosa Rajaratne]

Hello Rich,

Thank you for your important input!

I wrote to Proteus and they said the same. Also, I connected it to the return line (from the anode), which may have introduced a high load of stray voltage through water. Usually it is advised to have the flow switch connected to the supply line, much away from the anode. Therefore I am inclined to think that the electronics may have been damaged due to interference.

Unfortunately now the flow switch does not seem to be working anymore.

But thank you very much for helping!
Tharosa

[Rich Feldman]

Glad that was helpful.
I hadn't heard of XPS before yesterday.
But would have guessed the x-ray sources would have grounded water-cooled anodes (along with beryllium windows), like those for x-ray diffraction.
Does XPS use monochromatic characteristic radiation, or a tunable spectrum?

Does your HV power supply need water cooling, or just the anode?

If there's a nuisance leakage current through the coolant fluid, could it be diverted by having some grounded metal pipe in the path between HV and the flowmeter? Might also consider flow switches with more primitive, less sensitive mechanisms, even if they are less accurate and less failsafe.