Page 18 - SACE Tmax XT - Catalogue

1/14 SACE TMAX XT LOW VOLTAGE MOLDED CASE CIRCUIT-BREAKERS

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Construction characteristics

All the SACE Tmax XT molded case circuit-breakers are built in
accordance with the following constructional characteristics.

Double insulation Positive operation
The Tmax XT circuit-breaker has double insulation The operating lever always indicates the precise
between the live power parts (excluding the position of the moving contacts of the cir-
terminals) and the front parts of the apparatus cuit-breaker, thereby guaranteeing safe and reli-
where the operator works during normal opera- able signals, in compliance with IEC 60073 and
tion. The seat of each electrical accessory is com- IEC 60417-2 Standards (I = Closed; O = Open;
pletely segregated from the power circuit, pre- yellow-green line = open due to protection trip).
venting any risk of contact with live parts. The The circuit-breaker operating mechanism has a
operating mechanism especially is completely free release regardless of the pressure on the le-
insulated from the powered circuits. ver and the speed of operation. Protection trip-
Furthermore, the circuit-breaker has oversized ping automatically opens the moving contacts: to
insulation, both between the live internal parts close them again, the operating mechanism must
and near the connection terminals. Furthermore, first be reset by pushing the operating lever from
the distances exceed those required by the IEC the intermediate position to the lowest open po-
Standards and fully comply with the prescriptions sition.
of the UL 489 Standard.

Insulation behaviour Tropicalization
In the open position, the circuit-breaker guaran- Circuit-breakers and accessories in the Tmax XT
tees insulation distances in compliance with the series are tested in compliance with the IEC
IEC 60947-2 Standard, thus preventing leakage 60068-2-30 Standard, carrying out 2 cycles at 55 °C
currents to flow between the input and output with the “variant 1” method (clause 7.3.3).
terminals. The suitability of the Tmax XT series under the
most severe environmental conditions is further
ensured with the hot-humid climate according to
climatograph 8 in the IEC 60721-2-1 Standards
thanks to:
• molded insulating cases made of synthetic
resins reinforced with glass fibers;
• anti-corrosion treatment of the main metallic
parts;
• Fe/Zn 12 zinc-plating (ISO 2081) protected by a
conversion layer, free from hexavalent chromium
(ROHS-compliant), with the same corrosion re-
sistance guaranteed by ISO 4520 class 2C;
• application of anti-condensation protection for
electronic overcurrent releases and relative
accessories.