How can a device like the ETP BD-10A pass electrical safety testing?
- First what does the manual say? ( see below)
- Second what is a relevant standard document that defines these requirements?
- EN61010-2017 $726
BD-50EV User Manual
The Model BD-50EV generates a high voltage corona of approximately 500 kHz. However by the very nature of its design, it will produce electromagnetic interference (EMI) as a result of its operation. Electric arc welders, for example, are another product that by its very nature and mode of operation produces EMI.
As a result, the Model BD-50EV cannot meet the European Union
Electromagnetic Compatibility (EMC) Directive 89/336/EEC, and cannot be CE
marked. It does, however, meet EN61010-1:1993 Safety Requirements for Electrical Equipment for Measurement, Control and Laboratory Use, following the
provisions of the Low Voltage Directive 73/23/EEC, as amended by 93/68/EEC
I see that this project detects vacuum leakage by an arc detection of a defined gap and voltage (50kV) . I suggest all you need is 5kV by reducing the 1.4mm gap or less using a tungsten tip sparkplug to achieve 500V PD @ 1Atm and thus >5kV PD or BDV @ <0.08 Atm. PD is the precursor of BDV and behaves like a unijunction discharge before the pC (picocoulomb) arc discharge across the gap. Sparkplugs are also very inexpensive and have tungsten tips for longevity.
Partial Discharge (PD) is a "Type Test" for high voltage insulation that is a better way to detect vacuum or contaminants than BDV. ( Research will tell you much more about this topic)
See Paschen's curve below which I recall applies to parallel smooth gap at with >300V arc @ 0.1mm or 3kV/mm. Raising either air pressure, or vacuum increases the breakdown voltage (BDV) while changing to sharp pins reduces the BDV by 50%. Dust or contaminants may reduce more and the purest insulator dielectrics better than air may raise BDV it up to 10~30x air BDV.
Thus below 0.080Atm BDV rises sharply from 10x BDV @ 1Atm so depending on your vacuum failure threshold a smaller gap than 3kV for a typical sparkplug, by reducing the gap to 500V then use 5kV for a threshold of >0.08 Atm.
Electrode variations of shape and sharpness and contaminants can cause variations and dielectric contaminants may cause Relaxation Osc. Partial Discharge. (PD) start around 1 pulse/minute and rising with voltage or loss of vacuum.
Having done these types of tests before you must limit the discharge energy and ensure there are no explosive particles or hydrocarbon fluids that can generate explosive gas (H2 and methane).
Your only obligation is HIPOT and LEAKAGE testing for AC powered instruments and a safe insulation ground, EMI shield and safe wiring & procedures. Commercial Instruments used by qualified personnel have more relaxed requirements. ESD tests are advisable for immunity and safety with 100 discharges to any point outside the box up to 7kV no fault and 15kV no damage.
This is what I would use.
Tungsten tip, threaded nuts with gasket. 6 threads min.
Test BDV at 1 atm. then test at Vaccum fail threshold and choose that voltage.
Here 1.6mm gap in air 1 atm., PDIV = 3kV+/-0.1kV BDV slightly higher or same if clean. Then use a full length of auto. carbon conductor sparkplug wire to limit current and EMI.
If you want to read new product compliance specs, EN61010-2017, you have to buy it.
1.2.1 Aspects included in scope
The purpose of the requirements of this standard is to ensure that HAZARDS to the OPERATOR and the surrounding area are reduced to a tolerable level.
Requirements for protection against particular types of HAZARD are given in Clauses 6 to 13, as follows:
- a) electric shock or burn (see Clause 6);
- b) mechanical HAZARDS (see Clauses 7 and 8);
- c) spread of fire from the equipment (see Clause 9);
- d) excessive temperature (see Clause 10);
- e) effects of fluids and fluid pressure (see Clause 11);
- f) effects of radiation, including lasers sources, and sonic and ultrasonic pressure (see Clause 12);
- g) liberated gases, explosion and implosion (see Clause 13).
Requirements for protection against HAZARDS arising from REASONABLY FORESEEABLE MISUSE and ergonomic factors are specified in Clause 16.
RISK assessment for HAZARDS or environments not fully covered above is specified in Clause 17.
NOTE Attention is drawn to the existence of additional requirements regarding the health and safety of labour forces.