Hazardous Voltage Isolation

[Dusty4]

Hi Guys,
Just wondering what is common practice for monitoring isolation in a conversion. Below is quoted from ncop14 which is the guideline for conversions in australia. Are there any off the shelf monitors? I know it is implemented in some commercial BMS.
"Any HAZV traction battery system must be isolated from the chassis of the vehicle, and also
from any auxiliary ELV components and wiring. Isolation must be designed such that there is a
leakage current of less than 20 mA between any part of the HAZV system and either the chassis
or ELV components in the vehicle, measured when the vehicle is at rest.
This requirement means that both the HAZV battery pack positive, and the HAZV battery pack
negative, are to be floating relative to the chassis during normal operation, and both are to be
treated as HAZV components.
A ground fault detection circuit or device may be used to identify that either the battery pack
positive or battery pack negative have come into contact with the chassis or ELV part of the
vehicle, and flag this as a fault to the driver or service technician."

[SciroccoEV]

Many people are doing nothing! Several of the OEM BMS systems have isolation monitoring built in, the question then is if anyone is doing anything with isolation errors.

I talked to Bender UK Ltd. at CENEX-LCV a couple of years ago and they have several modules the can be used for isolation monitoring. They'll sell to individuals and the cost was reasonable.

[Dusty4]

Thanks Paul, I'll make an enquiry with them

[celeron55]

Somebody just mentioned the Sendyne SIM100 in another thread that I forgot.

Any chance you can quote the prices in this thread? I think many are considering whether or not to add monitoring and are expecting prices to be too high.

(Personally I'm using nothing in my conversion, but two of my chargers are unisolated which means EVSEs can and will measure ground faults for me.)

[arber333]

Somebody just mentioned the Sendyne SIM100 in another thread that I forgot.

Any chance you can quote the prices in this thread? I think many are considering whether or not to add monitoring and are expecting prices to be too high.

(Personally I'm using nothing in my conversion, but two of my chargers are unisolated which means EVSEs can and will measure ground faults for me.)

Yeah well, i had the same problems with EVSE. Back when my car was supplying 12V to the charger. Of course i did trip several EVSE GFCI.
I have solved that innitially by not connecting 3phase PE line to my car. Of course CP and PP circuit still had PE connected but no further. Of course this is hazardous.
Today i am running Outlander charger on single phase AND EMW 3phase non isolated charger alongside each other. And i have 3phase PE line connected to the car because Outlander charger wouldnt work without it. The trick is i had to completely isolate EMW charger from 12V aux supply in my car.
I am using one 12V 10A LED PSU to run my fans and charger controls. to control charger i am using wifi module and i have BMS pull a 12V relay to interrupt the charger. Also if charger is not touching the car chassis i am good for 18kW charging.

I did actually try to connect Outlander charger from one side of the EVSE and EMW charger on the other . I was using two EVSE cables. It didnt work because EMW is not isolated and immediately when i connected Outlander charger GFCI would see 12V GND connected to battery HV- and threw EVSE out... DOH!

[celeron55]

...

Wait what, you had your charger's HV side unisolated from the 12V side? I don't mean that. I mean the charger's high voltage DC and AC are unisolated from each other, but are isolated from 12V. The former is definitely not safe, the latter just needs an AC input contactor to be safe. But what you're saying proves that the chargers will detect ground faults if any are visible to them.

[dougyip]

Dusty4, nice to see that you are looking into the issue. As Scirocco EV mentioned, most in the DIY community do not monitor isolation. It is especially important if you are modifying battery packs. We have seen instances where pouch cells fail and cause an isolation issue (electrolyte leaks and causes electrical path to ground).

The Orion2 BMS has built-in isolation monitoring. Not as fast responding as the Bender or Sendyne systems, but useful. We display isolation to the driver with a warning instead of trying to do an automated shutdown. A full throttle shutdown would probably blow up the the inverter, contactors etc.

[arber333]

...

Wait what, you had your charger's HV side unisolated from the 12V side? I don't mean that. I mean the charger's high voltage DC and AC are unisolated from each other, but are isolated from 12V. The former is definitely not safe, the latter just needs an AC input contactor to be safe. But what you're saying proves that the chargers will detect ground faults if any are visible to them.

Yeah that was in the early 2013 when not all EVSE had good GF circuits. Nowadays everything has to be isolated from 12V aux voltage if you want buck/boost type charger to work reliably. Of course i dont rely solely on IGBT to turn off and stay off. I have AC contactor on input and DC contactor on output and to top that off i use 100A output diode. This way HV battery never sees the output cap before charger is ready to output HV.

[Dusty4]

I reached out to bender UK and they referred me to captech which is they're Australian distributor. They quoted me approx $600aus for the iso165c-1 and $700aus for ir155-3203. which is approx €390 and €450 respectively. I am still waiting to hear back from sendyne.

[Dusty4]

I have had a reply from sendyne they quoted $300us for the sim100, motec Canada quoted the same.

[SciroccoEV]

Some good information in this Texas Instruments app note;

tidudj6.pdf

(799.63 KiB) Downloaded 158 times

[SciroccoEV]

Seems Tom had already read this app note;

https://github.com/Tom-evnut/SimpISO

[Dusty4]

Hey Paul,
Yeah I did see that, I asked Tom if it was something he was looking at for simpbms but he felt that after reviewing the products from bender and others that the effort would be too great.

[Dusty4]

A member of the Australian Ev forum suggested I look at the ground fault detector in a imiev. I looked up part numbers and couldn't find too much, but after looking at earlier outlander schematics I found they have one too P/n 9499d325. Which comes up at a number of places with a web search. This link is an outlander service manual.
http://mmc-manuals.ru/manuals/outlander ... dex_M1.htm

[johnspark]

Some good information in this Texas Instruments app note;
tidudj6.pdf

I really, really, really like this!!!! All high voltage aspects have been carefully considered and then a HV Isolation System has been designed, and once again carefully tested by TI.
You know years ago, in substations, the HV DC would be the 110VDC battery banks, and all the wiring in the control room and out into the yard for the High voltage circuit breaker trip and close circuits. Quite literally there would be at least 1km of wire connecting to these battery banks. The battery chargers would always have a system of detecting either the 110VDC + or 110VDC - gone down to ground. It would give out a red light if one side was down. This system was used for many years. it was basically a high resistance circuit to ground from the centre of the battery.