Martin Gregorie
August 3rd 04, 10:49 AM
Thanks for that, Larry: caused me to go and do some reading, and most
interesting it was too.
It looks like the type I quoted would be fine for our purposes (in
series with a 7 AH 12v gel cell). Its a general purpose type. The
hold current is 5 amps at 20C reducing to 2.4 A at 85C. Minimum trip
level 8.5 amps at 20C, trip time 2 secs at 25 A. Untripped resistance
0.017 ohms. This type would appear to be suitable for the type of load
we apply in a glider.
It also looks like the temperature environment is fine if we mount the
device on the battery and install the combination in the cockpit.
On Tue, 03 Aug 2004 03:27:15 GMT, Larry Goddard >
wrote:
>These resettable fuses are good devices. I use them in the ::Goddard:: power
>supply units that we manufacture.
>
>Look closely at the specs because they have an ambiguous range in their
>behavior. You will normally find two specifications rather than one such as "5
>amp" on fuses. These units will have 'guaranteed break' and 'guaranteed hold'
>ratings. For instance, the guaranteed break point might be 5 amps, but the
>guaranteed hold would be only 3 amps. In between these two points the condition
>is ambiguous... might be "on" and might be "off". So pick a device where the
>"guaranteed hold" rating is a somewhat above the minimum required. then you
>should be fine.
>
>Larry Goddard
>"01" Zero One
>USA
>
>
>
>Martin Gregorie wrote:
>
>> On Mon, 02 Aug 2004 21:26:57 +1000, Graeme Cant >
>> wrote:
>>
>> >Martin Gregorie wrote:
>> >
>> > > Put spade connectors on the battery connected to the XLR inline socket
>> >> by a short length of mains cable and while you're on the job fit a
>> >> self-resetting fuse in the positive line. These are inexpensive solid
>> >> state devices that go open circuit if overloaded and turn back on
>> >> after 30 seconds or so.
>> >
>> >My batteries are set up as you describe but I use spade connector auto
>> >fuses. Can you give a make/model or URL for those self-resetting fuses
>> >you mention?
>> >
>> RS Components Cat No 283-8784. This is rated for 5A fuse and 16v, cost
>> £0.854 each. Orders must be multiples of 5.
>>
>> I'm actually using a blue rectangular unit with the part number
>> AN2-5A. These were fitted when I bought the glider. I've run web
>> searches, but can't identify the brand or a source for them. I believe
>> they have a similar rating to the RS part.
>>
>>
>> --
>> martin@ : Martin Gregorie
>> gregorie : Harlow, UK
>> demon :
>> co : Zappa fan & glider pilot
>> uk :
--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :
interesting it was too.
It looks like the type I quoted would be fine for our purposes (in
series with a 7 AH 12v gel cell). Its a general purpose type. The
hold current is 5 amps at 20C reducing to 2.4 A at 85C. Minimum trip
level 8.5 amps at 20C, trip time 2 secs at 25 A. Untripped resistance
0.017 ohms. This type would appear to be suitable for the type of load
we apply in a glider.
It also looks like the temperature environment is fine if we mount the
device on the battery and install the combination in the cockpit.
On Tue, 03 Aug 2004 03:27:15 GMT, Larry Goddard >
wrote:
>These resettable fuses are good devices. I use them in the ::Goddard:: power
>supply units that we manufacture.
>
>Look closely at the specs because they have an ambiguous range in their
>behavior. You will normally find two specifications rather than one such as "5
>amp" on fuses. These units will have 'guaranteed break' and 'guaranteed hold'
>ratings. For instance, the guaranteed break point might be 5 amps, but the
>guaranteed hold would be only 3 amps. In between these two points the condition
>is ambiguous... might be "on" and might be "off". So pick a device where the
>"guaranteed hold" rating is a somewhat above the minimum required. then you
>should be fine.
>
>Larry Goddard
>"01" Zero One
>USA
>
>
>
>Martin Gregorie wrote:
>
>> On Mon, 02 Aug 2004 21:26:57 +1000, Graeme Cant >
>> wrote:
>>
>> >Martin Gregorie wrote:
>> >
>> > > Put spade connectors on the battery connected to the XLR inline socket
>> >> by a short length of mains cable and while you're on the job fit a
>> >> self-resetting fuse in the positive line. These are inexpensive solid
>> >> state devices that go open circuit if overloaded and turn back on
>> >> after 30 seconds or so.
>> >
>> >My batteries are set up as you describe but I use spade connector auto
>> >fuses. Can you give a make/model or URL for those self-resetting fuses
>> >you mention?
>> >
>> RS Components Cat No 283-8784. This is rated for 5A fuse and 16v, cost
>> £0.854 each. Orders must be multiples of 5.
>>
>> I'm actually using a blue rectangular unit with the part number
>> AN2-5A. These were fitted when I bought the glider. I've run web
>> searches, but can't identify the brand or a source for them. I believe
>> they have a similar rating to the RS part.
>>
>>
>> --
>> martin@ : Martin Gregorie
>> gregorie : Harlow, UK
>> demon :
>> co : Zappa fan & glider pilot
>> uk :
--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :