STI-8.5x31.5-2, 2-pole fuse holder A9N15650

Design and Operating Parameters

The Acti9 STI fuse base is a two-pole fuse disconnector designed for 8.5 × 31.5 mm fuse links. The device is mounted on a DIN rail with a width of 36 mm (corresponding to two standard modules), and its installation depth is 44 mm - its compact dimensions facilitate installation even in densely populated switchboards.

The rated operating voltage is 400 V AC, while the insulation voltage reaches 500 V AC. The rated current ranges from 2-10 A, allowing its use in circuits with moderate loads. The short-circuit breaking capacity reaches 20 kA - sufficient to effectively protect the installation from the effects of faults in industrial and commercial environments.

The base supports two classes of fuse links:

• gG (general-purpose fuse) - protects against overload and short circuits, suitable for typical distribution circuits;
• aM (for motor circuits) - protects only against short circuits, resistant to high inrush currents of motors and transformers.

The enclosure provides an IP20 degree of protection at the terminals; when placed in a modular switchboard enclosure, it reaches IP40. The product complies with insulation class II.

Indication and Locking

A snap-in indicator on the front or bottom terminal indicates the presence of a fuse in the base. An optional neon lamp indicates a blown fuse - it remains off during normal operation and lights up red after the fuse has blown (version for operating voltage up to 400 V).

The device is equipped with additional space for a spare fuse and the ability to lock the switch with a padlock - the maximum pin diameter of the padlock is 8 mm.

Electrical Connection

The base uses screw-clamp terminals that support:

Wire Type	Cross-Section
Solid / Stranded	0.75-10 mm²
Flexible / Ferruled	0.33-6 mm²

The tightening torque is 2 N·m, and the wire stripping length is 12 mm.

Application and Compatibility

The STI base is suitable for applications where the installation requires a high breaking capacity while maintaining isolation function. Unlike conventional disconnectors, it should not be used as a stand-alone switch - its role is to disconnect the circuit by visibly (mechanically) opening the contacts by tilting the fuse carrier.

In a two-pole configuration, the base simultaneously disconnects both the phase and neutral poles - the factory sequence ensures that the phase opens before the neutral and the neutral closes before the phase.

Accessories are available for the base to extend its functionality:

• Link bar - for quick connection of several bases of the same type;
• Busbar connection - for supplying busbars up to a cross-section of 25 mm²;
• Device lock - for immobilizing the switch with a padlock;
• Snap-in terminal markers.

Standards and Operating Conditions

The product meets the requirements of the following standards:

• IEC EN 60947-3 - low-voltage switchgear and controlgear;
• IEC 60269-1/2 - low-voltage fuses;
• NF C 60-200 / NFC 63-210.

The degree of environmental pollution is 3. The operating temperature range is from -20°C to +60°C, and the storage temperature ranges from -40°C to +80°C.

The maximum power loss in the fuse link for the 8.5×31.5 mm size is 3 W.

The packaging contains at least 70% recycled cardboard - Schneider Electric uses secondary cardboard wherever logistically possible; however, some orders may contain primary cardboard until existing stock is depleted.