Supply Voltage Variations And Supply Voltage Dips - Siemens SINAMICS G130 Engineering Manual

1.2.8

Supply voltage variations and supply voltage dips

General
The voltage of the power supply systems is usually not constant but rather susceptible to noticeable changes, as a
result of load variations, switching operations and individual occurrences, such as short circuits. The connected
SINAMICS units are inevitably affected by these changes and show different reactions to them, depending on the
magnitude and duration as well as on the operating conditions of the drive. These reactions range from entirely
unaffected operation over operation with certain restrictions to the complete drive shut-down.
The following paragraphs deal with the most important types of supply voltage changes, their causes, magnitude and
duration. Afterwards the behaviour of SINAMICS units during supply voltage variations and supply voltage dips will
be explained.
Supply voltage variations are relatively slow, long-term increases or decreases of the RMS value (root mean
square value) of the supply voltage, which usually occur as a result of load variations in the power supply system, the
switching of the transformer tap changers and other operational adjustments in the power supply system.
According to EN 61000-2-4, it is possible, in European interconnected supply systems, to assume the following
typical variations in the nominal supply voltage V
Supply voltage dips are characterized by a sudden decrease in the supply voltage, followed by a restoration shortly
afterward. Supply voltage dips are usually associated with the emergence and disappearance of short-circuits or
other very large current increases in the supply (e.g. the starting of relatively large motors directly at the supply with
correspondingly high starting currents). Supply voltage dips vary quite a lot with regard to their depth and duration.
The depth of a supply voltage dip depends on the location of the short circuit and the current increase. If this occurs
close to the unit's connection point, the dip will be large, if it occurs far away from the connection point, it will be
small. The duration of the dip depends, when short circuits occur in the supply system, how quickly the protection
device, such as fuses or circuit breakers, respond and clear the short circuit.
In European interconnected supply systems, it is possible, according to EN 50160, to assume the following
approximate values for supply voltage dips:
The following diagram shows supply voltage dips in a typical, European interconnected supply system over a time
period of two months. The supply voltage dips are in the range of 0.5 • V
50 ms and 200 ms, whereby very large dips occur very seldom.
Supply voltage dips in a typical European interconnected supply system
Outside Europe, larger and longer supply voltage dips can occur more frequently, particularly in states with fewer
closely connected power supply systems, such as those in the USA, Russia, China or Australia. Here supply voltage
dips which last a second or longer must be expected.
Fundamental Principles and System Description
:
N
·
0.90 • V ≤ V
N
·
0.85 • V ≤ V
N
0.01 • V ≤ V ≤ V (very short-term, i.e. 10 ms to approx. 1 s)
N Line N
≤ 1.1 • V (continuously)
Line N
≤ 0.9 • V (short-term, i.e. < 1 min)
Line N
≤ V
N
SINAMICS Engineering Manual – November 2015
Engineering Information
≤ V with a duration of between
Line N
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