Page 7 - Changeover switch

ABB TRANSFER AND CHANGE-OVER SWITCHES 7
Source 1 Source 2
01
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Ensuring a constant power supply is critical

in typical change-over switch applications

01

Load

Source 1 Source 2 Source 1 Source 2 Source

Load Load Load 1 Load 2

Source 1 Source 2

Use in critical applications Typical generator Transformer
The most typical application for change- 2250kW / 11kV / 3P 12 / 16 MVA - 34,5 / 11 kV
over switches is utility and stand-by G G G G G
generating set applications where
change-over switches commutate
between two sources. Often the back-up MV-SG 11kV / 2000A
power source is a stand-by generator
set. These generator sets (Gen-sets)
are a fundamental part of many Critical MV-SG 11kV / 2000A MV-SG 11kV / 2000A
Power applications where a constant
and reliable source of electrical energy LV-SG 6000A / 400V LV-SG 6000A / 400V
is required. Load
LV-SG I 2500A / 400V LV-SG II 2500A / 400V
Ensuring back-up power
Change-over switches are used to switch
from the grid to the back-up in case of
a failure in the primary energy source.
They are typically dedicated switching
devices, consisting of two mechanically
interlocked switch-disconnectors and
a motor operator for electrical operation.
The switching device may also have Air handling unit (AHU) - Chiller - UPS - Secondary chiller water pump (SCHWP)
an integrated automatic control unit,
enabling fully automatic operations. Applications for change-over switches are not always between utility and generating set.
They are also used to provide secondary supply for e.g. air handling units, chillers and water pumps.