DIY Electric Car Forums banner

1 - 10 of 10 Posts

·
Registered
Joined
·
40 Posts
Discussion Starter #1
I have completed converting a 95 Acura Integra using Curtis AC-50 motor and 1238 controller. The company (which shall remain un-named) that sold me the motor and controller also sold me a 250A circuit breaker which he advised me would be a perfect compliment to my pair of 500 A fuses in the battery box(es). Even though the current rating was awfully low, the time delay before the breaker would open was evidently sufficient to allow most acceleration scenarios before opening. Well, the breaker worked fine for a couple of months and now it seems to want to pop open at random moments, even when drawing very low (or in some cases negative or charging current when using regen braking). I have since been advised that with an AC system, a circuit breaker is not necessary and not desirable, either. Can one or more of you experienced guys enlighten me? I like the idea of having a remote cable on my dashboard and have installed one -- allowing me to manually shut down the system in an emergency when none of the other safety devices (including inertial switch and two fuses) has already shut it down. I would like to put in a manual disconnect or maybe even a big toggle switch that could carry 500A of current but have been unsuccessful finding one. I have also been pretty unsuccessful in finding a bona fide DC circuit breaker that can carry that much current. IDdeas please, anyone?
 

·
Registered
Joined
·
725 Posts
Maybe you just got a bad one? Not sure I'd try to reinvent the wheel too much, the Airpax 250a breaker with the -53 delay should work fine for you. It does for many people! According to their data sheet, it should maintain 500a for at least 20 seconds, and 1000a for four seconds. Can your batteries? I know mine can't! :D

Mine has been in service for a few years of EV usage between me and the previous owner, still working fine on my EV which sees daily short term (a few seconds at a time) current up to 500a.
 

·
Registered
Joined
·
1,199 Posts
I may be out of my depth here, but is your breaker installed correctly.

I've heard/read that these breakers will not work correctly/fail if they are not installed in the vertical position. I hope this helps.

Jim
 

·
Registered
Joined
·
3,141 Posts
Mounting orientation is usually not a problem for circuit breakers. I looked over the data sheet and it seems the breaker should work fine, so I would suspect a defective breaker, possibly, or more likely another problem that is causing a very high current surge. Please provide the complete part number for the breaker to ascertain that it is properly rated, and also a wiring diagram and/or photos of how it is mounted and wired. DC breakers often need to have two or more poles wired in series, especially for higher voltages. :)

Mechanical shock and magnetic fields can cause a breaker to trip even without current flow, so that is a possibility. :confused:

Circuit breakers can and should be tested periodically, and there are companies with the equipment and expertise to do so. I have been involved in the design, manufacturing, and repair of circuit breaker testing equipment and I could test it for you, or possibly recommend a company in your area. It's also not difficult to make a circuit breaker tester. If you have or can obtain a large toroid transformer or a powerstat, you can run a heavy cable through the center hole one or two turns and you can get several thousand amps into the breaker. You would also need a way to adjust the primary voltage, which could be a 2kVA adjustable transformer such as this: http://www.mpja.com/2KVA-0-130VAC-Variable-Autotransformer/productinfo/15163+TR/

You can measure the current with a clamp-on ammeter up to about 1000A, but mostly you just want to take it to 500A and make sure it holds for 20-100 seconds or so per the graph for 53F curve. It should work on AC as well as DC. ;)

If you want to be able to observe the actual waveform and current value and trip time for a breaker, I have a couple dozen PC boards that have been removed from old "Ortmaster" test systems and connect to a parallel port on an old PC running MSDOS up to Win95. You need only add a small transformer for power, and a shunt (they are made for 1000A/100mV shunts) and you can run an AC or DC current into the breaker (even while installed on the vehicle) and observe the level of current that tripped it. I'm willing to practically give away these boards so if they are useful to you please contact me. :)
 

·
Registered
Joined
·
40 Posts
Discussion Starter #7
Here is the complete name data on a sticker on the side of the breaker:
0329 Line
JLE-1REC5R-30150-222
MAX V65 AIC 50,000
125 10,000
HERTZ DC
DELAY 53
TRIP AMPS 250
CIST. P/N 256622200
Aux SW 1A 80VDC
USE ON VERTICAL SURFACE ONLY
SPECIAL PURPOSE
NOT FOR GEN USE LOAD
I had it mounted with the switch handle on top - So I guess I violated the rule about mounting on a vertical surface; it was mounted on the horizontal floor of a Plexiglass box that houses most of the parts that are under the hood and out of the weather. I have removed the breaker and replaced it with a heavy solid copper conductor. I'm not sure I know how to attach a photo of the installation but I'll try.
 

Attachments

·
Registered
Joined
·
40 Posts
Discussion Starter #8
As you can see from the photo, the red three phase 00 cables that run from the controller to the motor are not shielded so I guess there's potential for some EM radiation from them. Nearly all the other current paths (120 V DC at high current) are carried by 00 cable that is stuffed inside grounded flexible aluminum conduit. All the batteries are surrounded on six sides by solid aluminum, part of the purpose being reduction in EMI (electromagnetic interference). I honestly believe the breaker has simply failed as it tends to pop at unpredictable and unrepeatable moments (sometimes at almost zero current or even during regen braking when negative current is passing through the breaker). The main question on my original post was to ask for verification of some advice I got from a couple of guys who allegedly wrote the code for the Curtis controller and hence, are very well checked out on AC powered EV's. That advice was that a pair of 500A fuses is more than enough safety to provide for an AC EV arrangement and that a separate circuit breaker is neither required nor desired. Any ideas about that?
 

·
Registered
Joined
·
230 Posts
The circuit breaker we used weaken to the point of immediate tripping after a few test drives. This didn't occur from multiple trips, just from operating currents within the rating.

During the period that it conducted current, it never once tripped to save our controller (albeit later discovered to be built with Chinese counterfeit MOSFETs about 10x worse than real parts).

We did have have the breaker mounted horizontally, but I doubt that had anything more to do with the failure than forgetting to mount it under a pentagram of chicken feathers.
 

·
Registered
Joined
·
3,141 Posts
A circuit breaker operates on a combination of electromagnetic, thermal, and mechanical systems. For a long time delay, there is often a heater element that trips the breaker when it gets hot enough. And breakers are also rated for a certain size wire, as external heating from an undersized conductor can heat the thermal element and cause premature tripping. A loose connection will also heat up quickly and cause "false" trips. And mounting the breaker horizontally (or in an unvented enclosure in a hot environment) may interfere with convection cooling and cause unwanted tripping.

In an EV it is also possible that a sudden mechanical jolt or heavy vibration may cause the breaker to trip. My father showed me that trick with a small breaker. He set it closed and then rapped it smartly on the table, and it immediately popped open. It is sensitive to which side you hit as well.

Many large breakers can be serviced, but I don't know if that is possible for yours. However, it is fairly easy to test as I described above.
 
1 - 10 of 10 Posts
Top