Birth of the Bruce

[matt_Hellyar]

Re: Birth of the Bruce

I have noticed something interesting on my last few roasts, some how there is some current coming through the shaft of my wiper motor into my roaster.

I get a slight tingle if i touch the drum with anything metal.

this might be one for Mal.

It is not coming directly from my power supply as the connections I have made are safe and no bare wires are in contact with any metal part of the motor or anything like that.

these last few roasts have tasted exceptionally good so there might be something to this... not. (no taste difference)

[coffeelust]

Re: Birth of the Bruce

Careful what you write here, Matt. Any talk of current coming through the metal and AMll red card you and you wont be allowed to roast at all until a qualified person has checked it out.
(Just kidding; hes probably stopped many a coffee widow from becoming a real widow )

[A_M]

Re: Birth of the Bruce

I have noticed something interesting on my last few roasts, some how there is some current coming through the shaft of my wiper motor into my roaster.

I get a slight tingle if i touch the drum with anything metal.

this might be one for Mal.

It is not coming directly from my power supply as the connections I have made are safe and no bare wires are in contact with any metal part of the motor or anything like that.

these last few roasts have tasted exceptionally good so there might be something to this... not. (no taste difference)

It would be unlikley for DC leakage to give you a tingle....

It is not winter..... And I doubt that your silk knickers will be a cause of static...  But posiable..

It could be the Powersupply (Can you provide details... lots of wires... was all I could see) breaking down and leakage internally to the output..

I can think of a number of ways to test... But as usual it can be dangerious.

Note: Even a tingle can KILL...  If you have a medical condition, a cut, low skin resistance, pacemaker etc etc a tingle can be the death of you.... or OTHERS

As  quick test... Not conclusive.... If ya have a good DVM...  You could run it with beans (exclusion zone and keep every one away) and at  diferent times try to take a measurement...  The issue here is getting a true and correct reading on both DC and AC...

You should have it tested correctly by a qualified person......

If it was the toaster or washing machine or TV most wold replace or call a service person in ASAP... It does not matter that the product is yours or you can not see how somthing might happen... 240V does not cARE HOW IT GETS TO GROUND AND WILL KILL YOU...

[reubster]

Re: Birth of the Bruce

It is not coming directly from my power supply as the connections I have made are safe and no bare wires are in contact with any metal part of the motor or anything like that.

As AM says, what type of supply are you using?

Assuming your powersupply is the only powersource connected to the roaster [ie no other AC connections for fan or lights]
It HAS to be comming from [or through] the powersupply.

It probably not a fault with your connections though,
It is more likely that your powersupply is putting out an induced high voltage on its terminals [ie The HV sits on top of the 12VDC]

The powersupply is connected to the motor and [I assume] the metal shaft of the motor is connected to the drum.
So you have an electrical path across the system.

Unfortunately, we live in a cost driven world: many "modern" powersupplies such as switchmode plug packs etc are designed to be used with double insulated products ......hence these supplies are not designed with a view to eliminate or properly isolate the very high voltages created inside them.
These high voltages can be "coupled" to the PS outputs.

This is just a theory as the most likely explanation, we really need to know what PS you are using.
I would certainly consider earthing the exposed metal, parts of your roaster

[matt_Hellyar]

Re: Birth of the Bruce

the PS is a big Computer style one.

I am running the motor in reverse, would that cause this?

[A_M]

Re: Birth of the Bruce

PS would be my guess....

[A_M]

Re: Birth of the Bruce

PS would be my guess....

How is the unit wired up... A quick look hints of lots of wires..

Are you using 12 or 24 volts ???


It realy should not matter..... But could explain some DC issues as to the + and - supply...

Earthing the drum etc will not fix the problem... But may protect you if you have an ELCB installed... Depending on the leakage.. It could just trip right now or at some stage in the future..

Get it checked out ASAP.

iBreack hell

[matt_Hellyar]

Re: Birth of the Bruce

Im using 12V and it is wired directly to the motor (I bypassed the plug on the motor)

the motor itself has two leads a red and a black, I have to wires coming from the PS, one + and one -, the PS is not earthed. (I could try earthing it)

I also have another motor for my new roaster that I have used a few times and have not experienced this problem with

[A_M]

Re: Birth of the Bruce

Im using 12V and it is wired directly to the motor (I bypassed the plug on the motor)

the motor itself has two leads a red and a black, I have to wires coming from the PS, one + and one -, the PS is not earthed. (I could try earthing it)

I also have another motor for my new roaster that I have used a few times and have not experienced this problem with

Two wires + and - , would suggest you have the system wired incorrectly ??

What colour wires linked / joined ?

+12  +5   Ground  -5  -12  thus   if  +12 and -5 = 17V   or +5 and -5 =10V 0r even a total of +24V

Have you confirmed the DC voltage being applied to teh motor ?

Depending on the wiring and earthing you could be experiencing any number of issues...

Check the voltage being developed on teh system  (roaster) as stated previously...

If AC then you have leakage and the PS is faulty.. This is dangerious...

[Dimal]

Re: Birth of the Bruce

If AC then you have leakage and the PS is faulty.. This is dangerious...

This could also originate from the inverter which typically operate in the 20+KHz range. A quick check of the frequency between the unit and earth will tell you. And yes, the PSU should be earthed.... Via the mains power cord. Do you have an Electrical Safety Switch Matt? If so and it is working correctly, leakage that you can actually feel should be enough to trip it, if it (the leakage) is arising from the mains supply.

In all honesty, I think you should arrange to visit your local qualified and licensed electrician and have him/her check it out for you; especially if there is a possibility that the leakage is originating from the mains power supply. Cant be too careful mate....
Mal.

[matt_Hellyar]

Re: Birth of the Bruce

Ok, I also think it is the PS.
I got the multi meter out yesterday arvo to do some checking and, of course, no problem. I could not feel the current anywhere (different parts of the roaster have a stronger tingle that others).
I have a good look at earthing the PS, but it does not have an earthing terminal. all it has is two AC in points (like screw down clamps) and four dc outs (two + and two -). It has a stainless body so I was thinking that i could just attach an earth to its casing and see what happens.

BTW, after no tingle in the arvo I did a roast last night and it had returned.

[matt_Hellyar]

Re: Birth of the Bruce

ok, it was the PS.
I didnt end up taking any readings with my multi meter, but I did try a different PS and no more tingles.

Problem solved.

and now back to Bruce, sorry Luwaks.

Matt