Controls, Safety & Regulation
Type 5MA3-F - Wired thermal fuses, for insertion into 8.5mm I.D. pocket (thermowells)

Type 5MA3-F - Wired thermal fuses, for insertion into 8.5mm I.D. pocket (thermowells)

Controls, Safety & Regulation
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Protection against overheating of liquids heaters when dry run condition occurs.

These thermal cut outs are designed to fit the pockets with 8.5 ID mounted in standard in the liquids heaters.

It may be possible to replace them when they triggered, but it requires a prior full audit of all components of the heater because the important overheating due to lack of water may have damaged other components.

Technical features

Fusible pellet: Organic compound.

Mechanism: Movable pellet actuated of a spring released by the fusion of the pellet.

Protection: By electrical insulation silicone boot, dia. 8mm.

Locking in the pocket: By silicone grommet

Nominal current rating: 16A 250V

The nominal current rating is the maximum current the fuse can carry without opening or deteriorate when subjected to a temperature known as the “holding temperature” (Th) for a limited time.

Holding temperature (Th): The fuse must not open or be destroyed when subjected to a temperature equal to Th-6°C for a period of 168 hours under nominal voltage and current.

Rated functioning temperature (Tf): It is the opening temperature of the fuse in a calibration oven, when subjected to a current less than 10 mA, when temperature rises at a speed of 0.5 to 1°C / min. The opening temperature must not be lower than Tf-10°C or above Tf under these conditions. This is the operating temperature Tf which is printed on the fuse and the protective sheath external of the leads.

Maximum temperature (Tm): It is the maximum temperature withstood by the fuse after opening without losing its insulating and mechanical properties.

This feature is critical in liquids heaters application, to determine the right position of TCO to avoid its destruction and re-energization of the electrical circuit by high temperature overshoot.

Insulation voltage between open contacts: ≥ 500V

Insulation resistance between open contacts: ≥ 0.2 MΩ @ 500V

Lead lengths: 500mm.

Leads: FEP 300V primary insulation, 1mm² gauge (AWG18), in a polyolefin sheath.

In red in the datasheet: Standard temperatures available from stock.

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