[Stephen Small]

Hi Brent

Pure mineral oil has high dielectric strength (which is why oil is used to quench arcing in switchgear), it’s all up to the additives in the hydraulic oil, and how contaminated it is.

I do know that Lucas and Shell produces specific ‘non-conductive’ hydraulic oils.

Cheers

Stephen.

[Brent Dais]

@james-dodwell I guess a question for the EEA and the NCLW is why are they wanting to add it to ECP46 when reviewed?

Excerpt from Practice notes attached

[Stephen Albrecht]

Hi Brent,

In terms of the ACOP for safety and health in tree work: Part 2, maintenance of trees around power lines, Clause 2.4 (b), I looked at this back in 2014. I queried with Tex On Site at that time regarding electrical testing of hydraulic tool circuits on EWPs, and also the portable hydraulic oil hoses used for hydraulic tools, e.g. podsaws. I was advised they do not do specific dielectric breakdown testing of hydraulic oil such as that done for mineral insulating oil used in transformers and switchgear. Hydraulic tool circuits on EWPs get tested as part of the insulated boom test. Hydraulic hose couplers, including that of the tool circuit, are bonded together with other metal components at the bucket area for this test. Hence, the hydraulic oil gets electrically tested as part of this test given the hydraulic oil is in contact with the couplers. In terms of portable hydraulic oil hoses used for hydraulic tools, electrical testing includes an end-to-end test. 40 kV ac is applied between the end hydraulic coupling fittings with the leakage current required to be under a certain micro-amp value. Again, given the hydraulic oil is in contact with the couplings, this test also electrically tests the oil.

ECP 46, Clause 2.6.10, refers to testing intervals. Based on ECP 46 High Voltage Live Line Work – Industry Practice Note, Table 2.6.10 within ECP 46 is to include “Insulated hydraulic hoses” and “Insulating hydraulic oil”, with test intervals “Not exceeding 6 months”.

In my view, both in terms of ACOP for safety and health in tree work: Part 2, maintenance of trees around power lines, and ECP 46, hydraulic oil is electrically tested as part of the standard range of periodic tests done on EWPs and hydraulic oil hoses used for hydraulic tools as detailed above. My understanding of mineral hydraulic oil is that it is inherently electrically non-conducting. Specific ‘electrically non-conducting’ hydraulic oil products are available. I have attached a technical data sheet of one ‘electrically non-conducting’ hydraulic oil product that has an electrical dielectric of > 30 kV. However, unless specifically stated as a requirement, dielectric breakdown testing of hydraulic oil in the same manner done for mineral insulating oil used in transformers and switchgear, would introduce unnecessary and costly compliance costs.

It my view, it would be prudent for the EEA NCLW
to review this issue and provide guidance to industry.

Regards

Stephen

Shell_Tellus_S2_V_46-TDS.pdf 233 KB PDF - Click to view

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[Brent Dais]

Thanks for the information Stephen and I agree with your comments.

In Victoria, they test the oil to 20kV

I have asked James to find out why they have recommended it be added to ECP46 and am in the process of following up with our EWP builder about oil they use.

Thanks Again Brent

[James Dodwell]

We’ve had a related query to this on Ask EEA, which our NCLW has responded to. Thought you might all appreciate the heads up.

https://eea.co.nz/questions/question/insulating-hydraulic-oil-testing-requirements-mewps-and-hydraulic-tool-hoses/

?

[Bill Doig]

Hi Brent

Finally got the information back on the product used in our EWP’s. Its Hytec Sub Zero. The tooling couplings are connected back to the live connection at the bucket when HV testing.

Regards

Bill

Hytec-Sub-Zero-32-TDS.pdf 335 KB PDF - Click to view

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[Brent Dais]

Thanks Bill

The information doesn’t give its dielectric strength, do you know what it is?

[Bill Doig]

Not sure but the hydraulic
couplings, operational handle and basket mounting point are all bonded to the test point and tested at the proof voltage. You could approach the manufacturers via that email address on the sheet