The Siemens SENTRON 18 VA bell transformer is an intermittent-duty signaling transformer for residential and commercial building applications. It steps down 230-240 V AC mains to safe 8 V or 12 V SELV secondary voltages — powering electromechanical doorbells, chimes, gongs, buzzers, and electric door opener mechanisms. An integrated PTC thermistor provides self-resetting short-circuit and overload protection, eliminating the need for external fusing and enabling maintenance-free operation in distribution boards. As a bell transformer per EN 61558-2-8, it is rated for short-duration intermittent operation — the standard duty cycle for doorbell and signaling applications.

Key Features

• 18 VA intermittent-duty rating — sized for residential and light commercial signaling
• Selectable 8 V / 12 V SELV secondary — compatible with standard bell products
• Built-in PTC auto-reset protection — no fuse replacement required
• Safety class II — no earth connection needed
• 4 kV primary-to-secondary isolation for reliable SELV separation
• Compact modular DIN rail housing for standard distribution boards

Technical Data

Applications

Residential and commercial building signaling: doorbell systems in single and multi-family homes, apartment intercom buzzers, office paging and alert systems, hotel room door chimes, and electric gate/door opener control circuits. Suitable for surface-mounted or flush-mounted distribution boards alongside circuit breakers and residual current devices.