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What does happen when an accidental connection of the conductor phase to the ground connection system of computer network and information technology (IT) systems occur?
Former Community Member
What does happen when an accidental connection of the conductor phase to the ground connection system of computer network and information technology (IT) systems occur? And What things can we do for preventing of this accidental ?
OK, so initially it behaves just like any other earth fault on a class I appliance - at the point of the fault the voltage goes up to something nasty (e.g. half Uo in the case of a TN system) and stays there until the protective device opens some tens, hundreds or even thousands of milliseconds later. Normally that'll provide adequate protection from electric shock.
The complication with IT systems is that you might have data connections referenced to the equipment's chassis earth. If it's just one item of equipment in isolation that's not too much of a problem - but if you have several items of equipmemet each with their own earth connection and earthed referenced data connections between them, you could see significant problems. Data circuits that expect to see a varying few volts d.c. suddenly have perhaps a hundred volts or more a.c. imposed on them - so physical damage is likely, and if the signal line happens to be in use at the time, data corrpution is probably inevitable. That said, earthed referenced data signals between equipment is getting rarer these days - most of the modern systems (e.g. twisted pair Ethernet) use a balanced system so are much more resilient on that count. Any sensible data centre will also have lots of supplementary bonding, duplicated c.p.c.s and by-pass earthing conductors (there's a separate standard for such things) which will significantly reduce the difference in earth potentials between different items of equipment.
OK, so initially it behaves just like any other earth fault on a class I appliance - at the point of the fault the voltage goes up to something nasty (e.g. half Uo in the case of a TN system) and stays there until the protective device opens some tens, hundreds or even thousands of milliseconds later. Normally that'll provide adequate protection from electric shock.
The complication with IT systems is that you might have data connections referenced to the equipment's chassis earth. If it's just one item of equipment in isolation that's not too much of a problem - but if you have several items of equipmemet each with their own earth connection and earthed referenced data connections between them, you could see significant problems. Data circuits that expect to see a varying few volts d.c. suddenly have perhaps a hundred volts or more a.c. imposed on them - so physical damage is likely, and if the signal line happens to be in use at the time, data corrpution is probably inevitable. That said, earthed referenced data signals between equipment is getting rarer these days - most of the modern systems (e.g. twisted pair Ethernet) use a balanced system so are much more resilient on that count. Any sensible data centre will also have lots of supplementary bonding, duplicated c.p.c.s and by-pass earthing conductors (there's a separate standard for such things) which will significantly reduce the difference in earth potentials between different items of equipment.
