Minimum reading allowed for pyro (insulation resistance)

mini2 · 16 Oct 2006

Minimum reading allowed for pyro (insulation resistance)

im getting 4.57/4.84

i was told anything aobve .5 is alright but must exceed 2meg in new installations

Maxxy · 16 Oct 2006

How longs the run? On a new installation you should be looking for better readings than that in my view

mini2 · 16 Oct 2006

1 meter

the readng ive been gettin are

45.7/48.4

had the point in the wrong plce

Adam_151 · 16 Oct 2006

Same as any other cable AFAIK

0.5 meg min, and under 2 meg you really ought to investigate it (and you really should be quite concerned IMHO quite a way before it gets as low as 2, lol)

securespark · 16 Oct 2006

Re-pot & re-test.

ricicle · 16 Oct 2006

Is it just an odd piece you are testing.Are the ends properly terminated or are they open and the cable has started to absorb moisture.Is it a very old piece that has a reduced Ins/Res

Ricicle

Adam_151 · 16 Oct 2006

Is there any truth to the rumour that modern MI has an additive to the MgO that makes it a lot less hydrosopic than the MI of old and what some people would have you believe?

plugwash · 16 Oct 2006

i saw one manufacturers website that said that, i dunno if its universal though.

mini2 · 16 Oct 2006

its just off cuts what was left from prvious jobs a while back which i found in my company office.

ricicle · 16 Oct 2006

Could be the reason for the low IR.By the way Adam it is Hygroscopic

Ricicle

mini2 · 16 Oct 2006

the legs are open yes

plus its old piece of mi

thanks

Jim2287 · 16 Oct 2006

if the MI dries out would the insulation improve again or is there some kind of reaction with the moisture and magnesium oxide?

being MgO, i guess no reaction

ricicle · 16 Oct 2006

I've heard the older guys say they used to dry MI cables out to improve IR by using a hand cranked megger.Any truth in that you more senior guys out there?

Ricicle

Jaymack · 16 Oct 2006

A method used for chasing out moisture in pyro.
After removing the pot, use the flame of a gas torch or blowlamp, starting about 2 metres from the end; and working towards the near pot end, retesting for the insulation value, if still low: - do the other end.

Jaymack

RF Lighting · 16 Oct 2006

Jaymack said:
A method used for chasing out moisture in pyro.
After removing the pot, use the flame of a gas torch or blowlamp, starting about 2 metres from the end; and working towards the near pot end, retesting for the insulation value, if still low: - do the other end.

Jaymack

We were shown this at college with an analogue megger connected to the potted end of the pyro, and then a blowtorch applied to the open, damp end.

The IR value steadily increased as the flame was brought nearer the end of the pyro.

I love pyro. What a good invention.

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Minimum reading allowed for pyro (insulation resistance)

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