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MG Midget and Sprite Technical - Current draw on electric fan
Any of you electrickery wizards know what the current draw of a typical electric fan motor is please?
Need an in-line fuse.....
|Oggers, I can't tell you what the rated current is although presumably the manufacturer would have that detail on line for whichever fan you have.|
My fan was from a Rover 400 (scrapyard). I run it with a 15A blade fuse. I tried a 10A but it occasionally blew that one, - I suspect the start up current was momentarily exceeding the 10A.
|Thanks Guy - appreciated. Searched for a nameplate/label but I suspect it went AWOL decades ago!|
|I reckon around 10 amps running, say 15/ 20A fuse to allow for starting current.|
|I'm behind again, I amended and stole this from elsewhere, as with Bill -|
if the fan is rated at 10 amps this is typically the running current, at start up fans can draw more amps by a good margin, typically a good starting point is 50% more amps in the fuse then round up to next size.
|Hm....I use a 20A fuse and that's the one that recently blew. Can't remember the make of the fan. Yes the ammeter shows 10 when running.|
|L B Rose|
|My logic was to start with a lowish value fuse, and if it blew, then move up one in size until I got a stable situation. This works if you can reasonably assume that the fan (or whatever else you are setting up) is working correctly, is in good condition and not undergoing any unusual stresses that might raise its current demand above normal. |
But yes, you do need to allow for higher starting current on motor start-up.
|Could be wiring problem or perhaps fan problem.
I'd think unless the fan has a very big draw a 20 amp fuse would take a lot to burn out so there'd have to be a sustained drag on the fan, unless of course the fan has died entirely and pulled the fuse.
If the fan works it might be an idea to check it whilst its turning to make sure there are no sticking or impact points, that the blades are clear of debris and not bent or buckled.
A large month stopped my fan this summer, I guess it got caught between the fan blade and rad, how it got in there I don't know as it was bigger than the rad grille holes.
If there's some sort of electrical short then 20 amps could go instantly.
Could you make up some test wires and go straight from your battery posts to the fan to test it to eliminate all wires and switches and then work back from there.
Is your fan operating through a relay?
I've copied this from previous thread to confirm my memory, Bill put -
>>Blown fuse for the fan relay circuit.<<
I rolled the relay in as a switch on my direct battery test.
Was that quote from Bill? Or was that a mistake?
I was asking Les about his.
|When this Bill fitted blade fuses to his midget he/I put a ten Amp fuse in the fan line.|
It ran fine with that until a couple of years ago on the Bridges run I lost the cooling fan in traffic.
The ten amp fuse had blown so I added a fifteen amp one in the car park of a Macdonalds in someplace in London.
It still has that fuse in it now, so I vote that 15A is the way to go.
I checked the circuit diagram for my Mondeo of the day.
That ran 15A in the fan circuit too.
|Guy sorry that quote was from Les.|
I was so pleased with myself remembering the relay I forgot the correct name!
I was going to put I've no idea why I put Bill but now realise I'm physic, pity I've missed the Euro draw I'll do tomorrow's numbers instead, 1, 15 and 20 will be included.
|the fuse in a circuit is there to protect the cable not what its running so you should not put a fuse in bigger than the cable can take.|
|True, I think we're on a 20+ amp dedicated cable.|
The 10 amp running taking out a 20 amp fuse, depending on fuse type and how quick it took to go, suggests a serious issue with the fan or circuit.
|If its any help, the instructions for my Kenlowe kit say the following:|
"Direct connection to fuse box, glass enclosed fuses, use either 25 or 35 amp rating. Porcelain open fuses use 16 amp rating".
Why there should be a difference I don't know, but it does not mention blade fuses.
It also says if in doubt, run a direct line to the battery, and check current draw.
with the fuses it's the difference between the running and blow rate, best example is the original, rather modern, glass fuses at 17 continuous 35 blow (as described in the Driver's Handbook).
This thread was discussed between 12/01/2018 and 13/01/2018
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