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