IEC60947-6-1 LV Switchover Directive

7/30/2019 IEC60947-6-1 LV Switchover Directive

1/3

DOES YOUR CURRENT CHANGEOVER SYSTEM

COMPLY WITH IEC 947-6-1?

THE LOW VOLTAGE DIRECTIVE FOR AUTOMATIC

TRANSFER SWITCHING AND ITS IMPLICATIONS ON

EMERGENCY POWER TRANSFER SYSTEMS

IntroductionThe low voltage directive was implemented to harmonise standards throughout

Europe. The section within this directive that relates to control gear and switchgear is

IEC 947. This document consists of the following individual standards that must

be complied with to obtain the CE mark on individual components : -

Part 1. General rules.Part 2. Circuit breakers.

Part 3. Switches, disconnectors, switch-disconnectors and fuse combination

units.

Part 4. Contactors and motor - starters.

Section 1 - Electromechanical contactors and motor - starters.

Part 5. Control circuit devices and switching elements.

Section 1 - Electromechanical control circuit devices.

Section 2 - Proximity switches.

Part 6. Multiple function equipment.

Section 1 - Automatic transfer switching equipment.

Part 7. Ancillary equipment.Section 1 - Terminal blocks and copper conductors.

This standard is now well understood and it is generally assumed that building a

complete switchboard or system from individual CE marked components will

constitute a complete CE approved system. This is correct in all cases other than

emergency power transfer systems or ATSE , which is a sub-assembly and has a

separate section within the standard.

Automatic Transfer Switching Equipment

The section of IEC 947 that is concerned with emergency power systems is

highlighted above i.e. IEC 947, Part 6, section 1

Automatic transfer switching equipment ( ATSE )

Defined as : - " Self acting equipment containing the transfer switch device(s) and

other necessary devices for monitoring supply circuits and transferring one or

more load circuits from one supply to another. "

( The above definition would have previously been known as a transfer or change-

over scheme. )

Page 1 of 3


2/3

Since the introduction of IEC 60947 any items used for the purpose of power transfer

must comply with IEC 947-6-1 and beclearly labelled as such.

To obtain compliance with IEC 947-6-1 a specific test regime must be adhered to. In

the case of Contactors and Circuit Breakers a different test regime is required by IEC

947.

e.g. : - IEC 947-4-1 ( Contactors )

IEC 947-2 ( Circuit Breaker)

The above devices (if used in a transfer scheme) need not be re-tested if their

individual test regime is at least as arduous as that of IEC 947-6-1 but even then

some special requirements are specified for ATSE duty : -

e.g. :-

"Contactors shall comply with the following utilisation categories (IEC 947-4-1)".

1) For ATSE with contact transfer time of 50ms or less : AC-4

2) For ATSE with contact transfer time longer than 50ms : AC-3

Testing to comply with IEC 947-6-1

The testing regime for different devices used as an ATSE will depend upon the

classification andutilisation category : -

Class PC: ATSE that is capable of making and withstanding, but is not intended forbreaking short-circuit currents.

Class CB : ATSE provided with over current releases and the main contacts of which

are capable of making and are intended for breaking short-circuit currents.

Utilisation Category A: ATSE intended for frequent operations.

Utilisation Category B: ATSE intended for infrequent operations.

Taking into consideration Class and Utilisation Category, a number of tests must be

carried out on thecomplete transfer system to establish performance :-

No of operations (on load and off)

Overload performance

Short-circuit performance ( make , break + withstand )

Over voltage performance

Dielectric properties

Temperature rise

Once these tests have been successfully completed the device can be labelled

IEC 947-6-1.

Labels shall clearly state : -

Page 2 of 3


3/3

a) The manufacturers name or trade mark.

b) Type designation or serial number.

c) Number of this standard if the manufacturer claims compliance.

d) Class of equipment : PC or CB.

e) Rated operational voltage(s).f) Utilisation category : A or B.

g) Rated frequency.

h) Rated short-circuit making capacity for Class PC and rated short-time

withstand current where applicable.

i) Rated conditional short-circuit current where applicable.

Conclusion

It is the responsibility of the manufacturer of thecomplete transfer system or ATSE

to

ensure compliance with IEC 947-6-1.A transfer scheme put together by an assemblerdoes not comply with the

requirements of IEC 947-6-1 unless it has been tested to IEC 947-6-1 as a complete

assembly and is labelled as such.

The EMC Directive became EEC Law on 1st January 1996, anyAutomatic Transfer Switching equipment installed in andmanufactured for the EEC market after that date must fullycomply with its technical requirements.

EEC Requirements:

Low Voltage Directive: 73/23/EEC

EMC Directive: 89/336/EEC

CE Marking Directive: 93/68/EEC

Applicable Standards:

EN60364 Electrical Installations of Buildings

EN60947 Low Voltage Switchgear and Controlgear

For further details please contact:

ASCO Power Technologies Limited

Fourth Avenue

Globe Park

Marlow

Buckinghamshire. SL7 1YG

Tel: 01628-403872

Fax: 01628-403867

Page 3 of 3

Documents

IEC60947-6-1 LV Switchover Directive