Functionality & features
As industrial processes and IT applications
diversify, a secure power supply is becoming
an increasingly important asset in the drive
to cut production and maintenance costs.
In emergency situations, the system logic
of power distribution can become complex
with mechanical devices looking after the
making, breaking, conducting and isolating
of power. Loads may sometimes need to
be transferred from one supply to another
— this will be the case when energy use
is restricted or when the supply source is
overloaded.

Application
The automatic transfer switch is managing different power supplies
to one or more load circuits and guarantees the continuity of
performance. The automatic transfer switch ensures the switching
and isolation between the primary network supply and the alternate
network supply or a standby generator. Type of operation is open
transition, i.e. break-before-make.
The automatic transfer switches can be operated in three ways,
local manual operation with handle, local manual operation with
the automatic control unit or full automatic operation done by
the automatic control unit. Manual operation, using a handle is
the simplest type of operation. Local manual operation with the
control unit enables to operate the switch electrically. Full automatic
operation ensures that loads are transferred automatically to the
secondary source in case of mains failure. Both local operation with
the control unit and full automatic operation enables a short switch-off
time between the normal and the alternative supply.
Automatic transfer switches shall be used for switching I, 0 and II
positions following types of loads:
• Off load application (AC 20A)
• Resistive loads (AC 21 or AC31)
• Mixed resistive and inductive loads (AC 22)
• Motor loads