Old printing machines, insulation resistance test fail.

[Brobat]

Hi , I've been testing some old ( prob 40 yrs plus) Heidelberg platen printing presses and on 3 of them I'm getting an IR reading of 0.10Mohms. These machines do have some electrical add ons that weren't on the standard machines. They're all 3 phase and earth and I'm testing them with a lead I've made with all 3 lives & the neutral connected together, so I'm testing them for earth bond and IR only. It seemed too much of a coincidence that 3 machines should show a 'fail' with the same reading. 

I wondered if anyone may have had some experience with this or something similar?

 Thanks

 

[Andy™]

might have surge protection

 

[Evans Electric]

Heidelberg  are probably  the best printing  machines in the  world  ,   the old ones specially are over engineered and run forever  ,  40 yrs old  has no bearing on it . 

Are these the  small one colour presses ?   Your not meggering  5 or 6 colour  presses are you ?     Are you meggering the control circuits  , CTE  transformers etc  .?      Do they have IR  driers attached ?  

I used to do a lot of work  at various printers and although I carried £5M  insurance   ,  other than installation  It is  best to leave those things to the specialists.  

I could imagine my megger beggering  up the drive electronics  on a 6 colour  .....probably cost me  the £5,000,000  in parts  & downtime .  

 

[Brobat]

No they’re not multicolour presses, as I put they’re platens, single colour, very mechanical . Basic single phase heater as it’s a hotfoiler. Old style contactors. No d.c control electronics. Also tried the test at 250v in case of surge protection with the same result.

 

[Sidewinder]

Need to understand where and how you are testing it.

At the supply end, right back to & through the machine?

At the machine end, back up the cable?

They are TPNE, have you isolated them from all other equipment and earth paths?

Locked to prevent being resurrected (again)