PARTIALLY TYPE TESTED ASSEMBLY (PTTA)

IEC 60439-1, defines a PTTA as: ‘A low-voltage switchgear and controlgear assembly, containing both type-tested and nontype- tested arrangements provided the latter are derived (e.g. by calculation) from type tested arrangements which have complied with the relevant tests’.   This means: • The assembly will be derived from a Type Tested Assembly. • Deviations...

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...

Current ratings

Rated current (In)   value of current, declared by the ASSEMBLY manufacturer taking into consideration the ratings of the components, their disposition and application, which can be carried without the temperature-rise of various parts of the ASSEMBLY exceeding specified limits under specified conditions   Rated peak withstand current (Ipk) value of peak short-circuit...

Voltage ratings

Rated voltage (Un) (of the ASSEMBLY) The ASSEMBLY manufacturer shall state the rated voltage(s) necessary for correct functioning of the ASSEMBLY.   Rated operational voltage (Ue) (of a circuit of an ASSEMBLY)   If different from the rated voltage of the ASSEMBLY, the ASSEMBLY manufacturer shall state the appropriate rated operational voltage of the circuit....

IEC 61439 series

For the new re-structured IEC 61439 series, the following parts are envisaged: – IEC 61439-1: General rules – IEC...

Electrical checks

Functional tests consist in checking the correct functioning of all the circuits (electrical and electromechanical) by simulating, as far as possible, the different service conditions of the assembly. For example, tests on current and voltage circuits can be carried out by supplying the secondary circuits of the CTs and VTs, without disconnecting the CTs from the circuit....

Mechanical checks

They shall be carried out complying with the relevant documents, making reference to the following specifications: - correct assembling of the equipment (connections and, on a random basis, proper tightening of the connections); - positioning and tightening of nuts and bolts; - mechanical locks and controls (rack-in locking devices, mechanical interlocks, key interlocks...

Further checks during testing

Visual inspections They are carried out visually taking into account: a) compliance of the assembly with diagrams, designations, drawings and type of enclosures, number and characteristics of equipment, cross-sectional area of conductors and presence of identification marks on cables and devices (initialing, inscriptions on plates, etc.); b) presence of components...

Routine verifications in compliance with

Routine verifications represent the final technical intervention of the assembly manufacturer before the delivery of the switchgear assembly completed and before invoicing and shipment to the customer. The Standard describes the verifications in the following order: - Degree of protection IP provided by an assembly enclosure It represents the first routine test prescribed...

Protection against direct contact

Protection against direct contact can be obtained both by means of the assembly construction itself as well as by means of complementary measures to be used during installation. The protective measures against direct contact are: - Protection by insulation of live parts Live parts shall be completely covered with an insulation which can only be removed by destruction....

Classification of assemblies

Assemblies may be classified according to different Factors : by the constructional typology, by the external design, by the installation conditions, by the function carried out.   Open-type and enclosed assemblies   According to the constructional typology the Standard IEC 61439-1 distinguishes between open-type and enclosed assemblies. -  Enclosed...

UL Standards (Electrical enclosures)

Industrial Control Panel Enclosures Products Listed under this category include enclosures that are intended to house open type industrial control panels. The basic standards used to investigate this category is UL 508A, the Standard of Safety for Industrial Control Panels, UL 508, the Standard of Safety for Industrial Control Equipment, and UL 50, the Standard of Safety for Enclosures for Electrical...