Advice Please

[ajones17]

I don't really know anything about PAT testing but our in-house PAT tester has tested 4 PCs and failed all of them as he said startup was drawing between 80 and 100VA and they're only allowed 50VA. As these are all Pentium 4 machines with 300-400W power supplies I would expect them to draw quite a lot of power but he said 'but they're not kettles, you don't leave a kettle switched on all day!' Can anyone throw any light on whether these machines are really dangerous and what would be normal for that type of machine?

 

[wh666-666]

Did he test them beyond startup?

PC's always draw a lot of power while starting up, they're designed to do so, the very essence of TDP. Once booted, they won't draw the same amount of power as they do at startup and only come close to drawing the same amount of power at full load, so his very anaology about a kettle is flawed. You cant blame him however, he's an electrician and not a PC hardware engineer.



Have you tested the PSU's yourself though with a voltometer or a PSU tester? Old or stock/OEM PSU's tend to be unstable and get moreso over time including how much they draw and what voltages they kick out to the hardware.

I would suggest this first. A P4 PC should be able to pass PAT even when booted up fresh.

 

[nellyp]

I can't see what what any of that has to do with PAT testing. The purpose of which is visual inspection, continuity, insulation and functional checks.

Has he said he'll dispose of the PC's for you?

 

[ajones17]

One machine was reading 100VA even after installling a brand new power supply, when the 4-pin CPU supply was unplugged from the motherboard the reading dropped but the reading stayed the same when all the hard drives were unplugged. I'm not sure how competent the tester is so I'm wondering if he's misinterpreting the results somewhere.

 

[Adam W]

... he said startup was drawing between 80 and 100VA and they're only allowed 50VA....

Maybe I've been doing PAT wrong but I've never heard that before - surely 100VA would only be drawing half an amp, at startup? I've never heard of a maximum permitted startup power consumption of 50VA either, or ever at all, nor would it be something I would test for.

... And in a move I should have made before I posted that, I'm off to check the COP.

 

[ajones17]

I can't see what what any of that has to do with PAT testing. The purpose of which is visual inspection, continuity, insulation and functional checks.

Has he said he'll dispose of the PC's for you?

Apparently he's saying everything should read 50VA or less, although he ignores if it's around 55. He's not trying to get hold of the equipment himself, we scrap items ourselves so they wouldn't be given to anyone but the scrap man. I'm just trying to understand what these results mean and what could be causing them in a machine with a brand new 400W PSU.

 

[ian.settle1]

Not taking efficency of the PSU into account then 50VA roughly eqautes to 50 watts which is a lot less than the 500 watts PSU.

I would say to him he is talking through his backside.

 

[Des 56]

You could bin the 4 pcs or alternatively bin the pat tester

 

[topquark]

Depends on what devices the machine has (extra hard disks, graphics cards etc). Nothing wrong with it drawing 100VA to start per se, but it should settle down a bit after POST has completed and the OS has finished boot up.

 

[ajones17]

Depends on what devices the machine has (extra hard disks, graphics cards etc). Nothing wrong with it drawing 100VA to start per se, but it should settle down a bit after POST has completed and the OS has finished boot up.

Trouble is he says his testing machine only measures for 5 seconds, and that's not enough time for the machine to load Windows. I am wondering whether there's an issue over decimal places here, whether the machine's set at 0.05 when it should be 0.5 or something, but I don't know how they work and whether he could be interpreting things incorrectly.

 

[ian.settle1]

Trouble is he says his testing machine only measures for 5 seconds, and that's not enough time for the machine to load Windows. I am wondering whether there's an issue over decimal places here, whether the machine's set at 0.05 when it should be 0.5 or something, but I don't know how they work and whether he could be interpreting things incorrectly.

Is he failing them or is the machine?

 

[ajones17]

Is he failing them or is the machine?

I don't know really, I think he's saying the machine's set at 0.05 so if it's 0.1 it fails.

 

[acat]

The only real issue is with the pat tester, when you consider everything inside a PC when it starts up everything is wanting power much the same as a motor starting up once everything is loaded it will settle down. How much power it draws is not relevant as previous posters have stated all he should be testing is for safety of use nothing else.

As previoulsy stated bin the pat tester problem solved.


Chris

 

[pattester]

I dont think think there is anything wrong with the pc's they always pull more on startup, his machine is probably not set to the right fields. As an "in house" pat tester does he do this all the time or just a couple of days per year?

 

[DurhamSparky]

sounds like a fool..

Contimuity OK
IR OK
Visual OK
Polarity OK

no obvious problems...!!

bin him

 

[ajones17]

I dont think think there is anything wrong with the pc's they always pull more on startup, his machine is probably not set to the right fields. As an "in house" pat tester does he do this all the time or just a couple of days per year?

Yes, I'm wondering whether the machine's set right, he does PAT testing all year round, we have around 400 computers plus various other equipment over several sites. He's done the training course but says the machine is set at what it's set at and he's inherited it from the previous guy (who's now in Aus). We also have several other electricians but the ones I've spoken to haven't trained in PAT testing so don't know how his machine works. I've intimated I don't think the machines are faulty and he's agreed to have another look at the situation on Monday, meanwhile 4 staff can't use their PCs

 

[pattester]

100VA is nothing, cant understand the failure

 

[Adam W]

Do you know what make and model of tester it is?
Personally i use one with 5 buttons and a switch on it so I wouldn't be much help, but maybe someone else could.