it being school holidays and too cold for the garden i have returned to cleaning some records using the HW17  in conjunction with the US cleaner from Owen Y.
the HW 17 is 110v. i was using a little 100w transformer which really struggled when the vacuum was in use so when a 1000w came up recently i grabbed it. wow! the suction was superb. but after an hour or 2 of use the vacuum stopped working, but not the table turner or fluid pump. strange. then a couple of hours later it worked just fine.

and today that process happened again, and my guess is the transformer is too big and the vacuum pump motor is getting hot and turning itself off. the machine is rated 300w and ideally i would have got a 500w transformer. is this what i should do? colinf - any thoughts?

My thoughts are you hit the nail on the head. On a vaguely and yet somehow completely unrelated topic, the idiot I work for thought he'd buy the biggest spa pool he could find to impress all his friends with. Thought he'd just whack a 10amp plug onto some 50amp heating elements and plug 'er into a wall socket... Oh dear.

Jul 11, 2017 15:01:37 GMT 12 rocl said:

it being school holidays and too cold for the garden i have returned to cleaning some records using the HW17  in conjunction with the US cleaner from Owen Y .
the HW 17 is 110v. i was using a little 100w transformer which really struggled when the vacuum was in use so when a 1000w came up recently i grabbed it. wow! the suction was superb. but after an hour or 2 of use the vacuum stopped working, but not the table turner or fluid pump. strange. then a couple of hours later it worked just fine.

and today that process happened again, and my guess is the transformer is too big and the vacuum pump motor is getting hot and turning itself off. the machine is rated 300w and ideally i would have got a 500w transformer. is this what i should do? colinf - any thoughts?

I researched the use of step down transformers recently, and what I learnt is that they transform voltage and not frequency.  Thus your HW17 is designed to run at 110V/60Hz, but what it is getting from the SDT is 110V/50Hz.  According to the experts that means a device designed to run at 60Hz will run a little hotter when receiving 50Hz, so that could be part of the problem.  A small motor driving a vacuuming action would likely turn itself off if it overheats after a prolonged period of use.  I'm not sure if using a 1000W transformer is the problem - I understand that the rating means the transformer will run continuously delivering a wattage a little less than 1000, so "should" only deliver full watts when demanded.  However, I am sure Owen Y can explain it better.

I anticipate a question you may ask - what about using SDTs with audio devices, which is a common enough practice?  The answer, is that except for many TT motors, audio devices run on DC, and their power supply converts AC to DC, thus frequency does not enter the equation.  At least, that is what I have understood from my reading/research.

Using a transformer with a greater rated wattage than is required will not cause a problem. It will only supply the current that the device will draw. A good example of this is a Geddon PSU which uses an overated 500w transformer to power a piddling little 3w turntable motor.
I think Sub is correct, the issue is the 50hz instead of the 60hz causing the vacuum motor to overheat. If this is a synchronous motor it will also be running about 15% slower on 50hz so if it has a cooling fan attached this will be less efficient also.
Bugger !!

sub and Graham - thank you for the replies. they have helped me understand what is happening. what had thrown me was that with the 100w SDT it hadn't happened even though i had used it for longer periods than the 1000w SDT. obviously it wasn't providing enough power to make the vacuum motor hot.

I agree, the vacuum pump could be running hotter on 50hz (depending on the motor's inductance, up to 20% hotter) so that the high temperature cutout could be clicking in. Most of them are set to trip at 70c, in some cases 90c. The reset temperature would be 55c (from 70c) or 70c (from 90c). So you'd have to wait for a while while the motor temperature comes back down to the reset temperature.
Having it operate from a large 115v stepdown transformer would ensure that the motor is running hotter, as the voltage from a smaller stepdown would sag slightly when the vacuum was on. If you run it from a smaller stepdown transformer, make sure it has a VA rating equal or more to the motor rating. Or the transformer could overheat too, and most stepdowns I've seen don't incorporate a temperature cutout.
To fix all this you could try running it at lower voltage, perhaps on a 100v stepdown transformer designed for Japanese domestic equipment. Or using it on a variable transformer. Try borrowing one first to see if that'll work.

AMR-iFi R&D

In my old Nitty Gritty, I increased the ventilation (drill some holes if necessary) - ie. help the motor stay cool.
The ventilation inside these boxes is a little vent or nil, so that doesn't help.

DarkLantern blog - darklanternforowen.wordpress.com

Adding ventilation would be good! Although that means modifying it.

AMR-iFi R&D