Office Building Solution

BU I LDI NG SOLUT IONS

9

— Power quality

— Interruptions are characterized in terms of duration.

— Accidental power outages

Long duration outages depend on permanent faults occurring in public distribution networks or within the user’s facility. The duration can vary from a few minutes to several hours in the most critical cases. European standard EN 50160 defines short interruptions as those lasting less than three minutes. Micro-interruptions are linked to faults occurring on the distributor’s networks that are eliminated by automatic reclosure operations. The duration is normally less than one second. Micro-interruptions do not have a regulatory definition.

All elements of an electrical system are sensitive, in different ways, to long or short voltage interruptions.

Voltage dips are commonly characterized in terms of amplitude and duration.

In addition to the events already mentioned that directly result in a power failure, a load can also be disturbed by events that occur on other lines in the same system, causing voltage drops on the power system. The magnitude of the disturbance may vary within wide limits depending on the distance between the point where the event occurs and the cabin busbars or the switchboard.

∆ U 10 ms < ∆ t < 60 s > 0,99 0,1< U n

U U n

Interruzioni brevi Long interruptions

Interruzioni lunghe Short interruptions

∆ t

∆ U

∆ U

U U n

> 0,99

> 0,99

U n

U n

1

∆ U U n

∆ t > 3 min

∆ t < 3 min

1

t

t

Schematic representation of a voltage dip.

∆ t

Voltage fluctuations cause undesired effects in all those users that require a stable power supply for proper operation. It is worth mentioning among others the whole IT world.

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