Red Tape

[poprock]

Hi; Some help needed. This is a quote from the Roads and Maritime Services NSW AU. Re acceptable current leakage :
     “ 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 then 29 mA between any part of the HAZV system and either the chassis or ELV components of 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 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. “
     In the definition of terms; may indicates an option; should indicates a recommendation.
     Must indicates mandatory.      So the ground fault detection circuit is an option.
     Checking resistance on a multimeter there is no leakage from either 72v pack positive or negative to 12v + or -. So my question is this. How do I check for the 29mA figure, as to what to use and where to connect? ( please keep it as simple as possible; I am a retired concretor and we are not known for high levels of intelligence)

[7circle]

Before fiddling around with the Multimeter

How is the EV configured?
DO you expect it to to be setup as an isolated HAZV system.
Does the system have a contactor?
When is it turned on.
Can the EV be safely enabled with out risk of it doing something unexpected?
DO the drive wheels need to lifted off the ground to spin freely for safety.
As the test is checking the whole electrical system including the motor when it is powered.


Make sure you know what your doing over 36Vdc is considered hazardous in some standards. So 72Vdc can be dangerous in many ways. assuming it's not a typo and you meant 720Vdc which for some on AEVA is what they have. It's all dangerous so be extra vigilant in your safety with procedures and steps.

Insulating gloves, safety glasses, non-flammable clothing.
Some people keep one hand in their pocket or behind there back so they don't react instinctively and grab something if they get a jolt.
ACCIDENTS ARE ACCIDENTS because they weren't expected!!

So for HAZV Battery to supply 29mA it needs a circuit loop with resistance.

The fault may only cause 36V (the mid point of the battery) to fault to the chassis or wiring.

So a fault current of 29mA from 36V needs to be tested for.

V= I x R
R = V / I
36V / 29mA = 1.241 kOhm
72V / 0.029A = 2482 ohm or about 2.5 kohm gives 28.8mA ag 72V
The power flow in the resisitor is 0.0288 A squared x 2500 or about 72V x 29mA
Which is about 2W so a 5W RESISTOR would be best chosen to not get extra hot.

So with a 2500ohm/5W resistor linked to a test lead and a voltmeter across the 2500ohm resistor

But better is a 72V Test Box with a selector switch with three resistors.
O/C - Open circuit - just the Voltmeter
100kohm 10W - in case 1000Vdc is present .... (what if charger is faulty ???)
1kohm 10W

And wiring with a 100mA Fuse.

If the system has a fault in the "isolation" and some part of the electrical system has a path to the ELV 12V positive or the chassis negative.
(IT COULD BE IN A CIRCUIT LIKE BRAKE LIGHTS OR INDICATORS THAT ONLY FUNCTION WHEN ENABLED. SO HOW DO YOU CHECK ALL POSSIBILITIES OF THE ELECTRICAL SYSTEMS?)

Do you expect that nothing will be damaged by this test.
Does the car have sensitive electronics.
Cars were NOT designed to have HAZV systems attached to them (other than the ignition spark system.)
So ECU and Radios and other electronics could be damaged.

So if you understand this so far then you might think about what tests need to be carried out with the "72V Test box"

There may be simpler/faster ways.. but if your claiming the "Concretor Angle"
Best to take it step by step.

[7circle]

Further thoughts...

If the fault is the motor wires and its an AC motor type, then the fault current will be AC not DC and the multimeter in DC measure mode will not show AC current.

Or if the charger has a fault and the AC input side is faulting to the DC battery output side.

Also if the fault point in the electrical system has resistance, such as
- from carbon dust from DC motor brushes
- wire insulation abrasion to a dirty or rusty chassis inter-connection
then the test resistance for 36V may be too large to show up 29mA, so a lower value will be needed.

Using a variable resistor can provide a resistance from 100k down to a 0ohm short circuit. So starting at 100k and varying down to low resistance while measuring the current and stopping if it goes over say 29mA, if you measure a current more than say 10mA you could already say there is a problem.

The parts of a EV system can have some leakage resistance and a capacitive charge effect. This can show up voltages just with the Multimeter's high impedance of over 1 megaohm. But once a small load is applied the voltage reduces and it can't supply significant current.

So I'm thinking an easier test circuit would be a $10 100k 2W 10 turn potentiometer that can handle 100mA in zero ohm / short circuit position.

So the usual test points are from HAZV Battery Positive or Negative to the Chassis as the this already is connected to the 12V negative.
But some EV's like gokarts, golf-carts or Fork lifts may not have a 12V system.

The test points with a voltage measurement of DC, then AC to check both signal types. If this shows up Zero Volts then things are looking good. But you may need to go through a sequence of EV function tests like Running motor, or charging the battery.

oops this got complicated.

[4Springs]

Have a look at this document: R100r1e
Annexe 4 describes a method of checking leakage current. It is very low tech.
For my vehicle I developed a procedure based on this one. I use an ordinary multimeter and a test resistor. I made up the resistor with banana plugs on it so that it would easily plug into the multimeter without having any exposed wire. The voltage for the test is provided by the traction pack. My procedure is written up in a way that I hope minimises risk of mistakes. I perform this procedure periodically (once a month or so), and every time that I want to work on the electrical system.
Sorry I'm not being more explicit, but your procedure or test equipment will need to be worked out for your vehicle. Post some more details here and we'll help you out!

[poprock]

Thank you for the replies. I have sent these with links to my leco and I will post the results soon thanks.

[Richo]

Checking resistance on a multimeter there is no leakage from either 72v pack positive or negative to 12v + or -.

The DMM is looking for a voltage to measure resistance.
If there is already a voltage on the circuit you are testing the DMM may give false values.
In most cases the DMM will report Open Loop (OL).
So measuring resistance directly to infer leakage is a no go.

Is someone requiring this information from you or are you just actively trying to quantify it?

[poprock]

As quoted in first post COLOR=red]“ 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 then 29 mA between any part of the HAZV system and either the chassis or ELV components of the vehicle, measured when the vehicle is at rest.[/COLOR] This is on p15 of the VMSS NSW RMS.( Vehicle standards bulletin 14 :-National Guidelines for The Installation of Electric Drives in Motor Vehicles. A licensed electrician has to sign off on the vehicle as to it meeting
AS/NZS 3000:2000.

[Richo]

Ah I see.
Tick the NA box.

Not even the AS/NZS 3000 considers 72V as hazardous - try 120VDC+
The NCOP14 doesn't define HAZV anyway.
NCOP14 doesn't make mention of requiring a signatory on it either.

Think about it - will touching your battery pack kill you?
If you're unsure don't try it
At 72V I would think you will get a bad tingle that would make you think about touching it too often.
NOT HAZV.
Tick the NA box.

[poprock]

NCOP version 2 jan 2011 p13. 2 technical requirements- electrical

[Astroboy]

Further thoughts...

If the fault is the motor wires and its an AC motor type, then the fault current will be AC not DC and the multimeter in DC measure mode will not show AC current.

Or if the charger has a fault and the AC input side is faulting to the DC battery output side.
...

They say with the vehicle at rest so the controller shouldn't be sending any voltage to the motor (DC or AC).
Also at rest implies not charging so this also would mean the AC mains input wouldn't be tested for leakage.
I think these are important tests but the qualification of the vehicle being "at rest" would exclude them from being a requirement.
At least that is how i would read it. An engineers opinion may differ.   

[jonescg]

For the West Australians, the Department of Transport has recently updated their website so it is MUCH easier to find information and paperwork on conversions.

http://www.transport.wa.gov.au/licensin ... ehicle.asp

Click to your heart's content! I will be making plans to get Voltron licensed before the next AGM in Perth

[Richo]

NCOP version 2 jan 2011 p13. 2 technical requirements- electrical

Ha I missed that one.
Well I see a revision coming on

[johnmc]

Sorry to break in on an old post, but just a quick question about licensing an EV in WA.
I see there's a link above to transport wa, which i'll have a read through when I get some more time (i'm overseas on holiday at the moment)
But I'm only just starting to look into converting an older vehicle, so wondering what problems I'll have with licensing it.
Is it very difficult in WA, like it is with everything else?
Or is it quite do-able with an older vehicle?
Cheers
John

[Richo]

do-able.
I haven't heard of anyone having any major problems yet.
If the car is registered then it's a "engine change" form.
But you will need to make sure that the car is in good condition and all operational as anyone would expect of a car of that era.
No point taking it in with rust holes in the sub frame and expecting it to pass.