TYPE TESTED ASSEMBLY (TTA)

IEC 60439-1, defines a TTA as:

 

‘A low-voltage switchgear and controlgear assembly conforming to an established type or

system without deviations likely to significantly influence the performance, from the typical

ASSEMBLY verified to be in accordance with this standard.’

 

This means:

• The generic design of the Assembly including all the various elements used in its

construction have completed the Type Tests detailed in the Standard.

• Deviations from the tested configuration are permitted, but they will be very

minor and not ‘likely to significantly influence the performance’ e.g. a functional unit

may have been short circuit tested in the top of the Assembly and in service be

located lower down.

• Design verification must be via stringent testing, and does not rely on subjective

assessments, calculations, safety margins and engineering judgements.

• The Assembly will consist of a series of standardized elements including

interconnections, all of which have previously been proven by tests in the Type

Tested Assembly(s), but may be configured differently to suit the application.

• Assemblies may be built by licensed assemblers under strict controls.

 

(BEAMA Installation)