12 Enclosed Switching Products 0115 ABB Low Voltage

Enclosed automatic transfer switches

General information

Automatic transfer switches

Automatic transfer switches comply with the standards listed below.

• IEC 60947-1:

Low voltage switchgear and control gear Part 1: General rules

• IEC 60947-3:

Low voltage switchgear and control gear Part 3: Switches,

disconnectors, switch-disconnectors and fuse-combination

• IEC 60947-6-1-PC: Low voltage switchgear and control gear

Part 6: Multiple function equipment – Transfer switching equipment

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

Design & safety

Automatic transfer switches are available as 3 or 4 pole versions.

All three positions I, 0 and II shall be stable and keep its positions in

case of supply failure or mechanical shocks.

The switch mechanism is located on the left hand side to the

switch’s power poles. The operating mechanism is of “quick make /

quick break” construction. The position indication markings on the

mechanism shall always show reliably the true position of the main

contacts. Automatic transfer switchs can be operated by direct

mounted handle and the handle shall be showing reliably the real

position of the main contacts of the transfer switch. The handle will

allow the switch to be padlocked in the off position.

The automatic transfer switch is constructed with a motor operator.

The motor operator is protected against overloads with a separate

overload fuse (160A to 1600A). The fuse is situated at the bottom

of the Motor. The 40A to 125A motor is protected by a resettable

overload button.

The accessories, i.e. terminal shrouds and auxiliary contacts shall be

mountable without any special tools (i.e. snap on mounting).

The terminals of the 160A to 1600A automatic transfer switch it

is possible to connect two parallel cables for easier installation

and space saving. All the terminals shall be finger protected with

or without separate terminal shrouds. All the metal parts shall be

protected against corrosion. The contact surfaces shall be silver-

plated to minimise contact resistance. The automatic transfer

switches meet the ROHS requirements and only recyclable material

is used. The current carrying plastic parts shall have high thermal,

mechanical and electrical properties and have V0 classification.

The voltage sensing wiring from the switch’s power poles to the

automatic control unit is done by the automatic transfer switch

manufacturer. Voltage sensing wires are double insulated.

Enclosed automatic transfer switches

with current ratings 40A … 1600A. The

enclosure complies with IP65 EN 60529

and finished in a RAL 7035 colour.

The ATS enclosures are designed to allow

adequate cabling space to allow installers

to terminate oversized cables.