# circuit breaker, or DC disconnect?



## dtbaker (Jan 5, 2008)

My 'kit' from KTA included a whomping 200amp double-pole circuit breaker intended to be put in reach of the driver between the most positive battery and shunt->contactor->motor. The issue is that the best place for me to put it seems to be poking up thru the floor under the parking brake (1997 suzuki swift / Geo Metro), and the problem is that the stubby little switch might be hard to grab in a panic....

I am wondering if I would be just as ok with a simple DC disconnect; they seem to be available with substanial big levers that would poke up nicely. There will be a 400 amp fuse upstream, do I really need the circuit breaker?

Or.... if someone HAS a picture of where they have mounted the 'kill switch' in a Geo/Swift, lemme know!


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## piotrsko (Dec 9, 2007)

in my experience: big amperage necessitates BIG contacts with appropriate REALLY BIG support hardware. Conversely, if it ain't REALLY BIG it ain't big amperage.

most circuit breakers have a lever that can be extended an inch buy just slipping some home made doo-dad over the lever and gluing it in place. since they are generally spring loaded to OFF, it does not require a lot of force to trip them to off. OTOH, under the p brake lever makes it easy to trip operating the p brake. I myself us the brake all the time for hills, bootlegger turns & such wierd stuff, and would hate to go powerless by whacking a large levered switch.

If you have a major emergency, another second to hand trip it won't make much of a difference, and it will pop fast enough in a over load condition.

my problem with just a fuse is that sometimes you just need it off NOW and don't want any excuses as to why not.


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## ww321q (Mar 28, 2008)

I have seen the breaker mounted under the hood and and a sliding plate over the switch hooked to a cable running to the inside of the car . J.W.


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## TX_Dj (Jul 25, 2008)

I could swear I'd seen you ask this question before... In fact you did... And here was my response:



TX_Dj said:


> dtbaker said:
> 
> 
> > but now I am pondering how to get the circuit breaker switch to poke up thru the floor like I want. Any good pictures out there on how and where to mount a 200a double-pole circuit breaker within reach of driver??
> ...


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## dtbaker (Jan 5, 2008)

similar for sure... my question THIS time was whether just a disconnect would do instead of the circuit breaker since i found some with longer levers..... But the ones with a high enough amp and volt rating are looking pretty big so I am back to original design I think...


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## dtbaker (Jan 5, 2008)

...just poking around in jcwhitney today getting ready to buy a choke cable for my circuit breaker, and noticed high-amp disconnects.... much cheaper than the big GE circuit breaker. Have people used these? Looks like they are rated for plenty of amps (500 or 1000). http://www.jcwhitney.com/autoparts/...0101&N=111+10201+600000441&rlid=group_listing


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## rfengineers (Jun 2, 2008)

dtbaker said:


> ...just poking around in jcwhitney today getting ready to buy a choke cable for my circuit breaker, and noticed high-amp disconnects.... much cheaper than the big GE circuit breaker. Have people used these? Looks like they are rated for plenty of amps (500 or 1000). http://www.jcwhitney.com/autoparts/...0101&N=111+10201+600000441&rlid=group_listing


I would be concerned about the Voltage handling capacity of these switches. I suspect they are rated for 12-Volt systems.


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## peggus (Feb 18, 2008)

Don't use those, they are NOT rated for the voltage



dtbaker said:


> ...just poking around in jcwhitney today getting ready to buy a choke cable for my circuit breaker, and noticed high-amp disconnects.... much cheaper than the big GE circuit breaker. Have people used these? Looks like they are rated for plenty of amps (500 or 1000). http://www.jcwhitney.com/autoparts/...0101&N=111+10201+600000441&rlid=group_listing


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## tj4fa (May 25, 2008)

I'm a little confused why you need either...

Is it to kill voltage to the motor quickly or act as a maintenance disconnect?

My schematic from EV America uses an Anderson connector to remove the battery pack voltage as a maintenance disconnect.

To kill power to the motor quickly while driving, I mounted a simple lighted on/off switch ($4-item) in series with an inertia switch that connects to the 12V coil on the primary contactor.

If I need to kill the power to the motor while driving (and not turning the ignition key switch off thereby killing everything and locking up the steering wheel), I just hit the switch that I mounted on my instrument panel.

The 12V ignition circuit power for the brake vacuum pump and other accessories still work as they get power seperate from the inertia/kill switch circuit.

Also, the kill switch is unmarked and acts as an additional anti-theft item for those who don't know what it is.

If it's for an overload/short in the High Voltage battery pack circuit, the EV America design has a fuse that will blow.


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## elevatorguy (Jul 26, 2007)

tj4fa said:


> I'm a little confused why you need either...
> 
> Is it to kill voltage to the motor quickly or as a maintenance disconnect?
> 
> ...


Ok, but if your controller goes full on and welds your main contactor together you are kind of stuck if you can't remove power from the controller.
Disconnects are a good thing..


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## tj4fa (May 25, 2008)

elevatorguy said:


> Ok, but if your controller goes full on and welds your main contactor together you are kind of stuck if you can't remove power from the controller.
> Disconnects are a good thing..


Good point...but let me think about that scenerio. 

Would that be from a full open pot box or a fault inside the controller?

Maybe that's why EV America's design uses a secondary contactor. The first contactor closes when the ignition switch is turned on, and the second one closes after the "gas pedal"/pot box throttle is depressed sending the signal to the controller.

In their design, when you take you foot off the "gas" the pot box closes the limit switch removing input to the secondary contactor and controller.

I think EVA's design is to avoid having the high voltage running inside the driving compartment.


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## elevatorguy (Jul 26, 2007)

I think EV americas use of 2 contactors in redundancy is a good idea but I would opt for some type of mechanical fail safe for a OMG failure. Most failures of a controller are full on. I have experienced this as well as some other members here.
You don't have to bring the power into the vehicle, a cable can operate a connector or breaker disconnect remotely.
If your vehicle is in a runaway and controller is on fire or wiring you would not want to hope your contactors work, you would want the power disconnected.
I will have fuses, circuit breakers and mechanical disconnects and hope I never use them.


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## dtbaker (Jan 5, 2008)

tj4fa said:


> I'm a little confused why you need either...
> 
> To kill power to the motor quickly while driving, I mounted a simple lighted on/off switch ($4-item) in series with an inertia switch that connects to the 12V coil on the primary contactor.
> 
> If it's for an overload/short in the High Voltage battery pack circuit, the EV America design has a fuse that will blow.


I've been told that it is wise to have a MANUAL switch on the high voltage side... it is (remotely) possible that fuses don't blow, or blow and maintain a puddle of lead still sending juice, and possible that contactors weld themselves together.

Hence.... kill switch on the low voltage side may not do the job, and a fuse may not either, or the DC fuse may take 'a while' to blow. Unfortunately, this means a fairly expensive switch because of the big amps/volts. I would go with a low-votage switch myself, but the more experienced EV builders all seem to suggest a breaker in the HV side.

d


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## tj4fa (May 25, 2008)

Sounds convincing about putting a CB or manual disconnect in is good practice especially hearing that the contactor(s) normally fail in the closed position.

So now It sounds like I need a few more additional things:

-A manual disconnect/CB of some sort
-A motor rev limiter to kill an unloaded motor in case of a runaway
-And maybe a precharge resistor if I already don't have one

Arrrghh


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## Jimdear2 (Oct 12, 2008)

tj4fa said:


> Sounds convincing about putting a CB or manual disconnect in is good practice especially hearing that the contactor(s) normally fail in the closed position.
> 
> So now It sounds like I need a few more additional things:
> 
> ...


Hi tj4fa,
I might have some help for you. 

Look at the Albright SD200 or SD300. A combination Main Contactor and Emergency Disconnect switch 

http://www.curtisinst.com/index.cfm?fuseaction=cDatasheets.dspListDS&CatID=7&siteID=1

/Disregard?This also has aux contacts arranged so you can have pre charge even with the contactor open.?Disregard

On the runaway thing. I have come up with two possible fixes.
The first is a set it forget it type system.
The second is the one I will use. Thats only because of the way I'll be using the EV. Plus I already have the tach from a previous vehicle.

Both use a hall sensor mounted on the motor (there are kits available) to produce the needed pulsed signal.

The first system uses an ISSPRO r4901 speed switch, http://www.isspro.com set up in its latching mode. 
1.) The speedswitch is set by ISSPRO to your rpm limit specs. 
2.) When the switch is powered the NC contacts close and energizes the main contactor operating coil circuit, closing the main contactor. 
3.)When RPM limit is reached, the speed switch will latch to its NO contacts, opening the main comntactor and shutting power off to the motor. 
4.) The switch stays latched in NO until it is manually reset.

In the second, I will use an Autometer 5 inch racing tachometer with a setable shift lght circuit. 
1.) The tach's internal; circuitry is set to supply a signal to the shift light circuit at the preset rpm. The shift light ihas been disconnected and that circuit is used to control a latching relay in the contactor operating coil circuit.
2.) Turn on the main switch and the relay latches to the NC position powering the contactor control circuit, closing the main contactor. 
3.) If the tach should reache the set point rpm, it delivers a voltage to the latching relay that cycles the relay, opens the contact at the NC position and shifts and latches itself into the NO position. 
4.) THe latching relay will remain in this position until manually reset.

Have a good one,
Jim


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## dtbaker (Jan 5, 2008)

tj4fa said:


> -A manual disconnect/CB of some sort


kta-ev.com and various other guys sell the monster single or double-pole circuit breakers. The only pain is that the switches are sort of stubby and not designed to accept a remote manual pull... I was thinking about poking it up thru the floor and putting it inline from my rear to fron batteries, but fabricating a weatherproof box underneath and reaching it under the parking brake is off-putting. I may just settle for engine bay with choke cable method.




tj4fa said:


> -A motor rev limiter to kill an unloaded motor in case of a runaway
> -And maybe a precharge resistor if I already don't have one
> Arrrghh


the rev limiter I have decided is 'optional' as a runaway might only happen if in neutral or the tranny breaks and I don't take my foot off the juice. It might fry the motor, but not injure anyone.

By precharge resistor... I dunno, but KTAs schematic puts a nifty little interlock relay between the charger and the main contactor that prevents you from driving off while charging.


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## ElectriCar (Jun 15, 2008)

Re welded contacts and an OMG minute because you can't stop it. 

Has this happened to anyone who had *proper sized contactors* in play? I know if one trys to skimp or doesn't know any better and goes with a 100A contactor for example and is trying to control 3 or 400 amps welded contacts could be a problem. I doubt properly sized contacts would be an issue.

I've seen numerous DC drives fault and "run away" in an industrial machine but the controller always has been able to stop it or the operator who hits a stop button which kills the contactor control power. I've never seen a machine fail like you're describing and machines use only one contactor vs. two we all use.

And I'm NOT going to have my pot box switch turn off a contactor every time I let off the pedal. That is a lot of unnecessary wear and tear on the contacts IMO and I'm not really interested in premature failure of a $200 relay.


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## etischer (Jun 16, 2008)

I just bought my 400 amp circuit breaker, it has a 24 volt input for external trip. So hooking up 24 volts to this input will shut the power off, it is used in conjunction with a GFI and is safety rated. I plan on connecting this input to a red mushroom button, much easier than a mechanical cable. 

you can buy a cable disconnect mechanism for just about any circuit breaker. Look up cable operated flange disconnect.

I think the most common reason contactors weld shut is because people don't know to precharge. Putting hundreds of volts across a discharged capacitor is basically a dead short.


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## ElectriCar (Jun 15, 2008)

Anyone know how long it takes to discharge them on the Curtis 1231? 

I've been wondering about just placing a higher ohm low watt resistor across the contacts to trickle charge them basically. Maybe a 2200 ohm 10 watt or such. That would allow just milliamps to constantly flow. However the DC converter could be a problem with it trying to trickle charge the battery.


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## Jimdear2 (Oct 12, 2008)

etischer said:


> I just bought my 400 amp circuit breaker, it has a 24 volt input for external trip. So hooking up 24 volts to this input will shut the power off, it is used in conjunction with a GFI and is safety rated. I plan on connecting this input to a red mushroom button, much easier than a mechanical cable.
> 
> you can buy a cable disconnect mechanism for just about any circuit breaker. Look up cable operated flange disconnect.


Could you tell me where you located this circuit breaker with the external trip. This could possibly solve a delema I am currently facing.

Thanks,
Jim


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## rfengineers (Jun 2, 2008)

ElectriCar said:


> Anyone know how long it takes to discharge them on the Curtis 1231?
> 
> I've been wondering about just placing a higher ohm low watt resistor across the contacts to trickle charge them basically. Maybe a 2200 ohm 10 watt or such. That would allow just milliamps to constantly flow. However the DC converter could be a problem with it trying to trickle charge the battery.


If by 'them' you mean the capacitors, my Curtis 1231 looses 1/2 of its charge in about 15-seconds.


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## kittydog42 (Sep 18, 2007)

You always want two means of disconnection, whether that is two contactors (as EV America suggests), or one contactor and a circuit breaker. It is the redundancy that is emphasized. Note that the circuit breakers are strictly used as manual disconnects since they are the most economical switch rated for the voltages used. They shouldn't be counted on to automatically trip on any sort of failure; you always want a fuse as well.


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## etischer (Jun 16, 2008)

Jimdear2 said:


> Could you tell me where you located this circuit breaker with the external trip. This could possibly solve a delema I am currently facing.
> 
> Thanks,
> Jim


EBay
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=120331848834


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## ElectriCar (Jun 15, 2008)

That breaker appears to be rated AC voltage only. DC (batteries) doesn't behave as AC does therefore the breakers and switches are made differently. 

When you disconnect DC under load it will continue to arc through the air to a point whereas AC won't as the voltage goes to zero volts 120 times per second. DC devices are made to handle those arcs. An AC device could potentially cause a fire if used to disconnect a battery pack under load.

Be sure you find one rated for DC to be absolutely sure you're ok.


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## dtbaker (Jan 5, 2008)

etischer said:


> EBay
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=120331848834


my circuit breaker is a little different.... and I am still trying to decide whether to cut a hole in floor under parking brake for direct manual access, or go thru firewall with a choke cable, and drill a hole in the toggle switch for the cable.

I like the idea of direct manual switch, BUT it would be quite a bit more work to build a box and cut flooring. installation would be kinda tricky to get to the cable clamps and such.

...stay tuned


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## tj4fa (May 25, 2008)

Now where is that recent thread showing a emergency disconect contactor when you need it...

Oh well...Here's a website that shows it. 

http://www.bridex.com.au/albright_sd150a_and_sd250a_switches.htm


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## dtbaker (Jan 5, 2008)

tj4fa said:


> ... a emergency disconect contactor ...
> http://www.bridex.com.au/albright_sd150a_and_sd250a_switches.htm


Now THAT is a cool disconnect! I am tempted to trade in my double pole circuit breaker if I can find one of these.... off I go googling....

ok I found this info:

data sheet:
http://www.globalepower.com/Datasheets/Contactors/Albright%20Color%20Data%20Sheets/Emergency%20Disconnects%20(ED%20and%20SD)/ED-SD%20LEAFLET.pdf

...looks like about 3" height from mounting surface to top of 'mushroom' in the on position; which would just clear my intended position below parking brake lever, but pose possible issues with accidental off-ing if fingers get caught between brake and button while letting off the brake... hhhmmmm.

unfortunately, I am not finding any US distributors right off the bat?!
how about any of ya'll that have used these things?

Looks like the combo contactor/disconnects are only single pole with a250 amp max (ok in my case) , plain disconnects could be double pole up to 400 amps. So, my question is would one single pole interrupting my 'most positive' lead be sufficient?


d


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## Jimdear2 (Oct 12, 2008)

dtbaker said:


> Now THAT is a cool disconnect! I am tempted to trade in my double pole circuit breaker if I can find one of these.... off I go googling....
> 
> d


I agree, it is a nice unit.

I have contacted the US distributors for Albright and am waiting for a quote on a SD200B. It seems it will be special order from England, 6 to 8 weeks.

Some more info from my research. the SD150 has been superceeded by the SD200 and the SD250 by the SD300.

Just like the SW series these are limited to 48 volt systems in the base contactor and 72 volt systems with the SD_00B series contactor (you need the B series mag blow outs when used in above 48 volt systems). 

They also have Key Lock versions that require a key to unlock the disconnect. 

The only failing I can see for this unit is that higher voltage systems cant use them.

I'll post the price when I get it

Jim


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## dtbaker (Jan 5, 2008)

Jimdear2 said:


> ...the SD150 has been superceeded by the SD200 and the SD250 by the SD300.
> ... these are limited to 48 volt systems in the base contactor and 72 volt systems with the SD_00B series contactor (you need the B series mag blow outs when used in above 48 volt systems).
> 
> The only failing I can see for this unit is that higher voltage systems cant use them.
> ...


dang, I thought I saw the sd250 was ok up to 96volts.... ?


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## tj4fa (May 25, 2008)

JimDear said:


> ...the SD150 has been superceeded by the SD200 and the SD250 by the SD300.
> ... these are limited to 48 volt systems in the base contactor and 72 volt systems with the SD_00B series contactor (you need the B series mag blow outs when used in above 48 volt systems).
> 
> The only failing I can see for this unit is that higher voltage systems cant use them.
> ...


 


dtbaker said:


> dang, I thought I saw the sd250 was ok up to 96volts.... ?


 
Huh??  

My EVA 144V system uses (2ea) Allbright SW-200 contactors rated at 250 Amps. One in the positive side and negative side of the series system and has the same amp rating as the SD250 series disconnect type contactor. 

My battery pack in series is 144V + with 220AH batteries.

Am I missing something here??


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## dtbaker (Jan 5, 2008)

tj4fa said:


> Huh??
> 
> My EVA 144V system uses (2ea) Allbright SW-200 contactors rated at 250 Amps. ...
> Am I missing something here??



kinda... I am questioning the capacity of the sd250a which is a combo contactor/disconnect with mushroom head. interesting combo... and may be a cool way to lower cost of contactor + disconnect. 
BUT, availability in US seems to be an issue.

I have an email in to a distributor, and will post response.

d


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## Jimdear2 (Oct 12, 2008)

tj4fa said:


> Huh??
> 
> My EVA 144V system uses (2ea) Allbright SW-200 contactors rated at 250 Amps. One in the positive side and negative side of the series system and has the same amp rating as the SD250 series disconnect type contactor.
> 
> ...


 
Sorry, yes you are missing something, The perrformance data sheet for the SW200 contactor.

Follow this link to the Curtis Albright Data Sheet and Manuals page, http://www.curtisinst.com/index.cfm?fuseaction=cDatasheets.dspListDS&CatID=7 
then down load the data sheet for the SW200. Go to the last page and you will find that Albright rates maximum voltage for the contactor at 90 volts. 

Ninty volts is Albright's highest rating for the SW and SD series contactors and the 90 volt rating comes only with mag blowouts.

Have a great day,
Jim


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## Jimdear2 (Oct 12, 2008)

dtbaker,

Sorry, my bad it is a maximum of 96 volts recommended.



dtbaker said:


> kinda... I am questioning the capacity of the sd250a which is a combo contactor/disconnect with mushroom head. interesting combo... and may be a cool way to lower cost of contactor + disconnect.
> BUT, availability in US seems to be an issue.
> 
> I have an email in to a distributor, and will post response.
> ...


I've been talking to them also. You have to go to the SD200B to get up to 90 volts (ERROR should be 96 volts) per the data sheet. The SD200 and 300 contactor/disconnect replace the SD150 and 250, you may find the older ones in various places. The A suffix denotes the unit without mag blow outs 

*Maximum Recommended Contact Voltages:*
SD200 48V D.C.​SD200B 96V D.C.

The above is an excerpt from their data sheet.

Delivery is from England 6 to 8 weeks. If I get a price on the SD200B with aux contacts and mag blow outs I'll post it

Hope this helps,
Jim


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## tj4fa (May 25, 2008)

Jimdear2 said:


> Sorry, yes you are missing something, The perrformance data sheet for the SW200 contactor.
> 
> Follow this link to the Curtis Albright Data Sheet and Manuals page, http://www.curtisinst.com/index.cfm?fuseaction=cDatasheets.dspListDS&CatID=7
> then down load the data sheet for the SW200. Go to the last page and you will find that Albright rates maximum voltage for the contactor at 90 volts.
> ...


So I guess Albright contactors are crap for EVs running higher than 96V then and I and a lot of other people have wasted our money... 

Since I'm stuck with them, I guess I'll just run them for now until they burn up.


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## Jimdear2 (Oct 12, 2008)

tj4fa,

I wouldn't call them crap, they appear to be very over designed and then derated for long life. I was just trying to explaine my earlier statements that had you "confused" about what I was saying.

I am going to buy a SD200 for my pulling tractor conversion and I have an SW200 that I'll be using in a garden tractor conversion.

From what I understand EVA is a good outfit, their experiance may tell them that what they sold you is/was the best available when you bought it. I don't see a large selection of high voltage, high amprage contactors out there.

It is just that if you ever have to break the circuit when under a high amprage and high voltage draw you *might* get welded points or burned contacts.

Jim


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## tj4fa (May 25, 2008)

Jim, 

I'm just trying to learn this electronics stuff as I go. 

I saw someone post the Albright emergency disconnect switch the other day and just passed the info on thinking it might help someone who didn't see it the first time.

Little did I know it wasn't rated high enough for some of us EVers. 

Terry


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## Jimdear2 (Oct 12, 2008)

Terry,

It was probably me that posted about the Albright SD200, I think they are a great idea. The redesign to incorperate the SW format made them look a lot more attractive.

I at first didn't think about the voltage ratings either, and was corrected by another member.

I am an just an old phart and am just learning this stuff too. Sorry if I came back too heavy.

There is no proof that these contactors are derated sxcept all of the people using them in >96 volt systems.

JIm


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## dtbaker (Jan 5, 2008)

Jimdear2 said:


> tj4fa,
> 
> ...I don't see a large selection of high voltage, high amprage contactors out there.
> 
> ...


hence the need for MANUAL circuit breaker/disconnect! This thread has clarified why KTA sent me a monster GE double-pole circuit breaker. I just wish that the switch was built for a cable end.... I feel nervous drilling a hole in it for the choke cable.

The albright mushroom combo was looking good, except I started thinking about how I don't really want the contactor all the way back under the floor, just the disconnect. Albright does make a plain single or double pole mushroom disconnect in 200 or 400 amps.... still thinking about that, but it WOULD be probably too tight under my parking brake lever.


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## Jimdear2 (Oct 12, 2008)

dtbaker said:


> hence the need for MANUAL circuit breaker/disconnect! This thread has clarified why KTA sent me a monster GE double-pole circuit breaker. I just wish that the switch was built for a cable end.... I feel nervous drilling a hole in it for the choke cable.
> 
> The albright mushroom combo was looking good, except I started thinking about how I don't really want the contactor all the way back under the floor, just the disconnect. Albright does make a plain single or double pole mushroom disconnect in 200 or 400 amps.... still thinking about that, but it WOULD be probably too tight under my parking brake lever.


If your interested, I have worked out a simple method to remotely operate the disconnect using a lever, some tubing a piece of rope and pull sstart handle.

Jim


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## dtbaker (Jan 5, 2008)

Jimdear2 said:


> If your interested, I have worked out a simple method to remotely operate the disconnect using a lever, some tubing a piece of rope and pull sstart handle.
> 
> Jim


absolutely post your picture, plan or whatever... current plan is to use a choke cable and drill a hole in the switch....

d


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