Hoffman Controls 905-347/480 Power Switch

The Hoffman Controls 905-347/480 is a high-performance, single-phase SCR power switch specifically engineered for resistive heating applications within industrial and commercial HVACR systems. Operating at 347/480V with a 28A capacity, this unit utilizes advanced zero-firing logic to connect resistive loads to line voltage while significantly reducing radio frequency interference (RFI). Designed as a direct, electrically compatible upgrade for the legacy 900 series, it incorporates an optimized H-type heat sink profile with vertical fins to maximize thermal convection and maintain component stability under heavy duty cycles. This single-phase power switch is often deployed in electric duct heater configurations, providing precision control when paired with 901-D or 901-DP series logic interfaces. The 905-347/480 features 12 AWG line leads and 22 AWG control leads, facilitating a straightforward 4-wire flying lead installation. For enhanced system protection, the unit includes thermal cutout monitoring capability to safely disable the switch if temperatures exceed rated limits, ensuring long-term reliability in high-voltage environments.

• EMI/RFI Reduction: Employs zero-voltage crossing firing to minimize electrical noise during high-current switching.
• Thermal Management: Features a high-efficiency aluminum heat sink designed for vertical mounting to ensure optimal heat dissipation.
• Retrofit Compatibility: Provides a 100% electrical match for older 900 series switches, utilizing the same mounting hole positions.
• Versatile Application: Suitable for single-phase or multi-phase arrangements, including In-line, Delta, or Wye configurations.

• How do I wire the control signal? Connect the W1(+) control signal to the 24VAC OUT 4 terminal and the W2(-) signal to the 24VAC OUT 3 terminal of your 901-D series logic.
• Can this handle higher current loads? While this specific model is rated for 28A at 480V, the 905 series chassis can accommodate up to 48 Amps depending on the specific branch circuit protection and ambient temperature de-rating.
• Does this require a new cabinet cutout? Yes, when upgrading from the 900 series, a new 2.0" wide by 4.5" high rectangular access hole is required for the larger 905 series footprint.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.