Fuses for Heater or Voltmeter?

[Bruce]

Hi,

   What type of fuse would be appropriate for the heater or voltmeter in an EV?  Both run off of pack voltage so each fuse would need to be rated for about 160 volts DC since that's what the pack would be hot off the charger.

   Specific part numbers would be great.  About 15 amps for the heater and 1/10 of an amp for the voltmeter, I think...

   Any suggestions?

                          Bruce

[leitmotif]

Not sure where you live but you need fuses that have standard rating 250 VDC.  Assuming you are in Seattle area maybe Home Depot better Mclendans and for sure any electrical distributor.

15 amp are so common you will have no trouble providing HD carries them in the first place.

I would fuse at 1/10 is tougher.  More than likely your source will be electrical distributor.
Dan Bentler

[Bruce]

...you need fuses that have standard rating 250 VDC....maybe Home Depot better Mclendans and for sure any electrical distributor...
Dan Bentler

I have looked at Home Depot and at McLendon's.  They have lots of AC rated fuses, but very few DC rated ones and none rated for 250 volts DC.  I would guess that fuses from electrical distributors would be AC (and not DC) rated too since they are serving the building industry.  I have searched Mouser and Digi-Key also without success.

I'm sure such fuses exist.  But where?  How is everyone else's heater or pack voltmeter fused?

[leitmotif]

Home Depto no surprise.  McLendons well a little - those guys are often pretty good electricians.  If your battery voltage is only 144 AND that includes the charging voltage (around 180 IF lead acid) then I THINK a 600 VAC fuse should work and should give you plenty of dieelettric (insulation) rating - you also need to be sure about interrupting rating.  Switches, circuit breakers etc are dual rated with the DC rating much lower.  Now that I think about it (since the vast majority of my work is all AC) I dont remember seeing fuses dual rated but then I have not had the need to worry about it for many years.

Where are you in Seattle?  I know a guy at Platt on 6th So who (with an introduction) will deal with you.  The electrical distributors are often leery of someone not in the trade just walking in off the street.

You can lookup at Shawmut (tt?) or Buss fuses they should have info.

Took a look in Grainger -- just for example  --
Class RK5 Time Delay Fuse, Current Rating 35 Amps, Diameter 13/16 Inch, Length 3 Inches, Type Ferrule,
250 VAC, 125 VDC,
200 K Amp Interrupting Rating @ 250 VAC,
20 K Amp Interrupting Rating @ 125 VDC
Grainger Item # 4A452   
Price (ea.) $9.02   
Brand BUSSMANN   
Mfr. Model # FRN-R-35

I have used a lot of these did not even look for the DC rating but like I said I was doing AC.
OK so Grainger is now a source for your heater and voltmeter fuses.  If your company has an account with them use the company name and pay with credit card.  If you say it is just you then they will get balky.

Took look at Shawmut
http://us.ferrazshawmut.com/catalog/general-purpose-fuses/ul-power-fuses/class-cc-general-purpose-atmr/

RatingsAC: 600VAC, 200kA I.R. IR = Interrupt rating
DC: 600VDC, 100kA I.R.

APPROVALS UL Listed
 
 General Purpose Fuses  UL Power Fuses  Class CC - General Purpose - ATMR

SMALL FUSE - BIG PROTECTION FOR GENERAL CIRCUITS Amp-trap ATMR fuses, in the Class CC family, are the smallest dimension 600V fuses suitable for branch circuit protection. The ATMR is a popular choice for economical protection of control circuits and control circuit transformers where available short circuit currents exceed 10,000 amperes. ATMR's rejection dimensions prevent substitution by lesser rated fuses. These fast acting fuses give current limiting protection to general circuits.

Features  Rejection style design prevents replacement errors when used with recommended fuse blocks
Fiberglass body provides dimensional stability in harsh industrial environments
Versatile design for individual component and branch circuit protection

Applications Control Circuits  Lighting  General Loads  Branch Circuit Protection

These otta be OK for you also.

Guess I dont know everything off the top of my head but I generally have a good idea where to get the answer.
Dan

[madderscience]

what's wrong with the 250v rated fuses at radio shack?  (the glass tube variety) or you can get slo-blow / ceramic ones as well.   These are what I am using for similar purposes in my car (heater, contactors, etc).  They can be had up to 30A.    Only thing is to be sure you have a good quality fuse holder for the higher amperage fuses; the cheap ones can't handle the current even if the fuse itself can.

[leitmotif]

Tell me their ratings.  They may be just fine.

Read my previous two posts.
Dan

[StorminN]

I believe glass automotive fuses (like type AGC) are rated for 250VDC...

The 15A one should be readily available at any automotive store or Radio Shack. For the 1/10A one, if you can't find it locally, you can get it online from Waytek Wire...

Waytek Wire

Waytek sells a fuse block for AGC fuses, it comes 12 fuses long, but you can snap it apart to make it any length you want. It's rated up to 30A and 300V.

I tried to post links to the individual items, but the links won't work, so...
The 1/10A AGC fuse is: item #46131
The break-apart AGC fuse block is: item #47065

FYI, Waytek also has high-amperage (100A to 400A) ANN and ANL fuses & holders, for those that are running smaller vehicles with pack voltages below 125V.

Hope this helps,
-Norm.

[Bruce]

what's wrong with the 250v rated fuses at radio shack?  (the glass tube variety) or you can get slo-blow / ceramic ones as well.

I believe glass automotive fuses (like type AGC) are rated for 250VDC...

I don't think there is anything wrong with using the fuses mentioned.  But a nit-picker would point out that technically none of them are rated for high voltage DC.

From surfing the web, this is what I have found:

AGC glass automotive fuses are rated 32 volts DC / 250 volts AC.

The ABC/3AB ceramic microwave oven fuses are rated 250 volts AC with no DC rating.

As I see it, possible problems with using a fuse not rated for high enough voltage could be:

 1) The fuse would not blow when it should - This seems unlikely.

 2) The fuse would blow when it shouldn't - Seems to me that amps are amps, no matter what the voltage rating is so this also seems unlikely.

 3) When it does blow, the fuse does not stay in one piece - This seems to be the most likely problem.  Too high a voltage could cause the fuse to blow with more energy, perhaps sending broken glass and small amounts of molten metal through the fuseholder.  Ceramic fuses should be better than glass.

But I'll bet there really are fuses rated for 250 volts DC out there somewhere... 

[leitmotif]

First and foremost

See my previous posts - in there I quoted a fuse rated for 600 VDC.
It is your equipment and your money. 
If you want to
save time and not evaluate your fuses for being the best choice
and you want to save a few bucks by purchase at Radio Shack
THEN
It is NOT my equipment,
it is NOT my problem
I do NOT have to fix it.

Fuses have a voltage rating ie for insulation.  This is how many volts they can withstand before breakdown to ground.  You should not use automotive rated wire for your main battery conductors.  They should be rated at the charging voltage plus a safety factor.  Insulation fails and you get a leak to ground not a big deal so far (may screw up your electronics though) - get a second leak now you just may have shorted the battery
BUT the good news is
not for long the wires will burn out and that is exactly how you start electrical fires.

Fuses have an interrupting current capacity - that is how many amps they can safely interrupt and contain the arc and all that - ie not create a fire in your equipment. 

Bruce you are basically correct fuses will blow based only on line amps -- actually it is I2R ie power dropped across the fuse ie heat but we wont get too technical.  Yes there are fuses that are rated at more than 250 VDC ie

Shawmutt fuse 
Ratings
AC: 600VAC, 200kA I.R.
DC: 600VDC, 100kA I.R.
IR = Interrupt rating  and yes, "k" in the interrupt ratings is 1,000.

APPROVALS UL Listed
 
 General Purpose Fuses  UL Power Fuses  Class CC - General Purpose - ATMR

SMALL FUSE - BIG PROTECTION FOR GENERAL CIRCUITS Amp-trap ATMR fuses, in the Class CC family, are the smallest dimension 600V fuses suitable for branch circuit protection. The ATMR is a popular choice for economical protection of control circuits and control circuit transformers where available short circuit currents exceed 10,000 amperes. ATMR's rejection dimensions prevent substitution by lesser rated fuses. These fast acting fuses give current limiting protection to general circuits.

Features  Rejection style design prevents replacement errors when used with recommended fuse blocks
Fiberglass body provides dimensional stability in harsh industrial environments
Versatile design for individual component and branch circuit protection

Applications Control Circuits  Lighting  General Loads  Branch Circuit Protection
http://us.ferrazshawmut.com/catalog/general-purpose-fuses/ul-power-fuses/class-cc-general-purpose-atmr/

BUSS fuse made a movie many years ago showing what happens when you do not use the correct fuse.  Really neat arcs n sparks and long lite shows and total meltdown of equipment.  That movie and some equipment meltdowns I have had to repair have shown me that there are good reasons that equipment is tested and rated it is a good idea to use that equipment to prevent problems.  I am just a journey level industrial, power plant and residential (family only please) electrician.  I have not killed anyone, have had no fires and I very rarely get callbacks  -- SO FAR - I intend to keep it that way.

Dan Bentler

[StorminN]

If the AGC's are only rated for 32VDC, then go with the class R fuses like Dan posted above. You can find them online also, like here:

15A class R fuse

-Norm.

[leitmotif]

If any of you guys need an introduction I am willing to introduce you to a guy at Platt Electric who may then be willing to sell to you.

North Coast seems pretty willing to sell to anyone who walks in off the street. 

The trick is to sound like you know what you are doing and what you need ie
I need  a fuse at XX amps for YY DC volts
Even better is Shawmut type (whatever I posted above) at 15 amp or whatever I need 3 one each for each line side and a spare.

Dan

[Paul]

A common size fuse makes it a lot easier to get a fuse holder. For this reason I like to use the 1/4 inch by 1-1/4 inch fuses. For the most part the glass body fuses in that size are NOT rated for DC voltage. If they are not rated for the duty they may not clear when they blow (you may end up with a big sustained arc where the fuse used to be.) Another outcome is that the fuse may explode when it blows, sending glass everywhere (I've experienced that a couple times before I learned.)

There are some ceramic body 1/4 by 1-1/4 inch fusses that are rated for either 250 or 125 VDC. The Bussmann/Cooper ABC line is what I generally use for the heater and instruments.
http://www.cooperbussmann.com/pdf/d2ab7442-15c0-4fb0-a097-345e95695061.pdf

[StorminN]

From the EVDL email list:

   From:      kk8m@att.net
   Subject:    Re: [EVDL] Small Hi Voltage DC fuses?
   Date:    October 26, 2008 8:02:18 PM PDT
   To:      ev@lists.sjsu.edu
   Reply-To:      ev@lists.sjsu.edu


Norm,

Those would work, but an RK5 fuse is rather large at about .75 diameter and
nearly six inches long. A better choice might be a Bussmann KLM or a
Littelfuse KLKD series fuse. You could also use a miniature ABC series fuse,
but not its cousin, the ubiquitous AGC (glass) fuse. When selecting
overcurrent protection for any circuit there are about four factors which
have to be considered: voltage, amperage, interrupting rating, and response
curve. When you get above 32 volts DC for a miniature fuse, or about 65-80
volts DC for a breaker you really have to start looking at whether the thing
is rated for DC and at what voltage and short circuit current rating. Some
breakers and fuses don't even have a DC rating.

The manufacturer's data sheets will tell whether or not a given fuse or
breaker even has a DC rating, and if so what voltage and current it is rated
to break. For example, I have some 80 amp breakers made for photovoltaic
applications which are only rated at about 60 volts DC and a maximum input
current of 200 amps. This means that they would not be suitable for EV use
because the low interrupting rating would typically be exceeded by all but
the wimpiest batteries. Other breakers require multiple poles to be
connected in series in order to get up beyond their 80 volt rating and it is
not uncommon to see a breaker which is rated at 480 VAC derated to only
150VDC. Unfortunately the cantankerous nature of direct current makes it
much tougher to open the circuit under load and have the overcurrent
protective device (or switch) clear the circuit without being destroyed in
the process.

Tom Bowes


>Something like this?
>
>http://www.grainger.com/Grainger/items/4A457
>
>-Norm.


>>On Oct 21, 2008, at 10:06 AM, John G. Lussmyer wrote:
>>
>>I'm looking for some fuses for pack voltage (up to 160VDC), that only
>>need to be 1A (or even less).
>>Anyone know where I can find such fuses?