Can You Help Me Out Here, Please?

[securespark]

Does anybody know what one of these is?

A switch for disconnection from the electricity supply, having a contact separation in all poles that provide full disconnection under overvoltage category III conditions.

Can't find it in the regs.

 

[martinxxxxxx]

PER IEC1010 OVERVOLTAGE INSTALLATION CATEGORY

OVERVOLTAGE CATEGORY I
Equipment of OVERVOLTAGE CATEGORY I is equipment for connection to circuits in
which measures are taken to limit the transient overvoltages to an appropriate low level.
Note – Examples include protected electronic circuits.

OVERVOLTAGE CATEGORY II
Equipment of OVERVOLTAGE CATEGORY II is energy-consuming equipment to be
supplied from the fixed installation.
Note – Examples include household, office, and laboratory appliances.

OVERVOLTAGE CATEGORY III
Equipment of OVERVOLTAGE CATEGORY III is equipment in fixed installations.
Note – Examples include switches in the fixed installation and some equipment for
industrial use with permanent connection to the fixed installation.

OVERVOLTAGE CATEGORY IV
Equipment of OVERVOLTAGE CATEGORY IV is for use at the origin of the installation.
Note – Examples include electricity meters and primary over-current protection equipment

 

[martinxxxxxx]

http://ecmweb.com/content/does-your-meter-safety-measure

 

[JohnW2]

Can't find it in the regs.

See Table 44.4 of BGB - these appear to be based on the definitions in EIC/EN 60364.

Kind Regards, John

 

[securespark]

Thanks guys.

But what is FULL DISCONNECTION?

Is it something more than plain old disconnection?

 

[PrenticeBoyofDerry]

But what is FULL DISCONNECTION?

A contact separation in a pole so as to ensure the equivalent of basic insulation between the supply mains and those parts intended to be disconnected

 

[JohnW2]

Thanks guys. But what is FULL DISCONNECTION? Is it something more than plain old disconnection?

Dunno - does it perhaps mean 'all-pole' disconnection?

Kind Regards, John

 

[JohnW2]

But what is FULL DISCONNECTION?

A contact separation in a pole so as to ensure the equivalent of basic insulation between the supply mains and those parts intended to be disconnected

Fair enough - but, as securespark implicitly was asking, what lesser form of 'disconnection' could there be? Do I take it that air is an acceptable insulator in this regard?

Kind Regards, John

 

[PrenticeBoyofDerry]

Well relates to the contact gap, so I would say yes air was acceptable, providing it is equivalent to the basic insulation.

 

[JohnW2]

Well relates to the contact gap, so I would say yes air was acceptable, providing it is equivalent to the basic insulation.

Thanks - so we're still stuck with the question of what "non-full" disconnection would/might be - any ideas?

Kind Regards, John

 

[Spark123]

A semiconductor device does not provide disconnection??

 

[EFLImpudence]

Thanks - so we're still stuck with the question of what "non-full" disconnection would/might be - any ideas.

I don't think 'full disconnection' is as dubious as is being made out.

Doesn't it relate to the 3mm. clearance that is often quoted in MIs.

I presume that for higher voltage this distance is greater so the 'full disconnection' will be whatever is appropriate for the device and voltage - either nominal or over.
(Although I can't find anything stating the different values.)

The categories relate to the insulation of the device (as in our test equipment).

 

[JohnW2]

I don't think 'full disconnection' is as dubious as is being made out. Doesn't it relate to the 3mm. clearance that is often quoted in MIs.

Maybe - you tell me!

I never said that 'full disconnection' is 'dubious' - if anything were dubious, I would have thought it would be 'non-full disconnection' (and I wonder what that would be deemed acceptable for)!

I presume that for higher voltage this distance is greater so the 'full disconnection' will be whatever is appropriate for the device and voltage - either nominal or over.
(Although I can't find anything stating the different values.)

That would certainly make sense.

Kind Regards, John

 

[EFLImpudence]

I never said that 'full disconnection' is 'dubious' - if anything were dubious, I would have thought it would be 'non-full disconnection' (and I wonder what that would be deemed acceptable for)!

I think you're splitting hairs.

Perhaps a better term to use would be 'safe disconnection' but you would then be asking what 'unsafe disconnection' was to which the answer would be - disconnection which was not safe enough for all possible scenarios.

 

[JohnW2]

I never said that 'full disconnection' is 'dubious' - if anything were dubious, I would have thought it would be 'non-full disconnection' (and I wonder what that would be deemed acceptable for)!

I think you're splitting hairs.
Perhaps a better term to use would be 'safe disconnection' but you would then be asking what 'unsafe disconnection' was to which the answer would be - disconnection which was not safe enough for all possible scenarios.

No, I'm not (at least, not deliberately) splitting hairs - I'm confused, and am really just echoing securespark's question. Are you saying that the word 'full' (which is, after all, what he was asking about) is essentially superfluous, so that your answer to his question is that the phrase 'full disconnection' simply means 'disconnection' which is (as one would probably assume, even without the 'full' word) satisfactory/safe? (a bit like the situation if I talked about 'full tests for dead'?)

Kind Regards, John