Why the Need for High Dielectric Refrigerant?

because the manufacturer said it should be used. That pretty much ends the discussion then manufacturers make the necessary oil that's needed similar to the transmission oil right It's a similar problem over there with all the motor generators and so on and so forth in the transmission so they came up with a way to mitigate whatever fears they thought or engineering prowess they had or what have you. I do know people that are running regular incorrect oil in their electric air compressor and it out lasted the car. Woops.. a lot of manufacturers do similar and a lot of people do write text asking questions and wondering why and some people just do what they want sometimes it works sometimes it doesn't.

 

I'm not completely sure that the magic of ND-Oil 11 is its own low conductivity. Maybe it is, I just don't know for sure.

The windings are already made of varnish-insulated wire, of course. They are all wound up on each other, so if not insulated, they would be dead shorts. The oil is already on the outside of the insulation, where its conductivity shouldn't matter a lot.

It seems to me they would be more concerned about the chemical compatibility of the oil with the varnish, so that it doesn't degrade the existing insulation on the windings.

 

Like what happens in large stationary AC units, moisture combines with contaminants in oil and deteriorates the insulation in wiring as Chap stated.

More AC compressors are killed by moisture than any other cause.

 

You've probably noticed the responses you got were not chiefly about electric shock hazard from conductive refrigerant.

There is published documentation from Toyota that's been cited on PriusChat before indicating that what they are trying to avoid is the failure of your A/C system with a P0AA6-611 code, requiring expensive replacement of pretty much all of the system ... and indicating the kind of astonishingly low fraction of contamination with non-ND-11 oil that can make that happen.

There are some threads here that link to a study by some A/C outfit (distinct from Toyota) where they deliberately filled a system using the wrong oil, then tested whether they could recover from that 'mistake' by just replacing the compressor (and receiver/dryer element, presumably) but only HECAT H-1000 flushing the rest of the system. That seemed to work out ok, for a cost much lower than replacing everything.

I'm not sure whether the refrigerant even gets into any areas where the high-voltage circuits inside the compressor are uninsulated. The windings themselves, of course, are insulated. Whether the circuit board in there is cooled directly by refrigerant, and has uninsulated connections exposed, I don't know for sure. Maybe someone here has taken one of those compressors apart and could comment.

 

Why do the ancillary components of the 800 volt system necessarily have to be 800 volts couldn't the compressor stay two or 300 or whatever just have some form of electronic circuit takes what it needs of the 800 volts to run the compressor the electric steering whatever else maybe high voltage might be deemed necessary?

 

Well, a circuit like that is called a DC/DC converter, and there's one in the car already to convert the battery voltage to 12 volts. It's good for about 1500 watts, and it takes up a bunch of space in the bottom of the inverter assembly, and needs coolant piped over it, and people get sad when it fails.

The A/C compressor can use around 3000 watts, so you'd be asking for another DC/DC converter in the car, of about twice the size and weight of the one that's there already (and would still be there), and would need twice the amount of coolant piped over it, and be another thing to make people sad when it fails.

Just building a compressor that can work at the battery voltage seems like it would save cost and weight and components.

 

Yepers it's always something.gotta make all new everything. No more parts bin cars like VW was so good at.

 

How about terminations of the windings? Are they embedded in insulating substance?

Interesting that 240 VAC stationary compressors apparently aren't as fussy.

 

I just haven't taken one apart enough to see where the terminations are, and where the refrigerant gets.

 

Everything in normal residential and commercial AC compressors is insulated and gets covered in oil and refrigerant. Just like in an inverter driven compressor. The difference is there is no high voltage leakage current check on normal compressors so minor leakage is of no concern unlike automotive inverter driven compressors.

 

Yeah I work on some of this stuff in the field and the commercial and light commercial HVAC and yeah the 240 volt compressors are pretty stout they can take a pretty good beating. Now these newer DC inverter job is they're finicky is all get out You look at them the wrong way and they'll shut down on you can't take any overcharging nothing It can't pound on the gas like an AC 3450 electric motor.