The Siemens SENTRON 4AC3740-1 is the most versatile member of the 40 VA safety transformer family, offering three selectable secondary voltages — 12 V, 16 V, and 24 V AC. Where the standard 4AC3740-0 provides 12 V and 24 V, the -1 variant adds the 16 V tap commonly required by specific Insta contactor models and European building automation standards. This makes it a universal stocking item for panel builders who encounter diverse control voltage requirements. Insulation class F construction handles higher thermal stress for continuous-duty applications.

Key Features

• Triple output voltages: 12 V, 16 V, and 24 V AC — one transformer for any SELV control need
• 40 VA continuous-duty rating — the workhorse power class for relay and contactor panels
• Insulation class F — higher thermal endurance than class E equivalents
• Built-in PTC auto-reset protection — maintenance-free operation
• Safety class II, 4 kV isolation, EN 61558-2-6 certified
• 3-module (54 mm) DIN rail format

Technical Data

Applications

Universal building automation panels: Insta contactor installations requiring 16 V, mixed-voltage control cabinets with 12 V and 24 V devices, stairwell lighting automation with diverse relay types, and HVAC control panels serving multiple subsystems. The three-voltage output eliminates the need to stock separate transformers for each control voltage.