S66AA-1C Johnson Controls SPEED Control

Overview

The Johnson Controls S66AA-1C is a professional-grade electronic fan speed controller and motor controller designed to modulate the speed of single-phase permanent split capacitor (PSC) or shaded pole motors approved for speed control by the manufacturer. It varies the motor speed in direct response to a 0–10 VDC analog input signal supplied by external sources referencing temperature, pressure, humidity, or flow. This controller is essential for maintaining efficient system operation in commercial HVAC systems and low ambient conditions, helping to prevent liquid slugging and evaporator freeze-ups by adjusting airflow across the coil.

Features

• Built-in hard start feature provides a brief burst of full voltage for approximately 1–2 seconds during startup if the signal is below the 50% threshold, ensuring the motor overcomes initial inertia.
• Integrated radio frequency interference (RFI) suppression for reduced electrical noise.
• Multi-tap voltage capability reduces stocking requirements by supporting multiple applications in a single unit.
• Transient protection with 320 V surge suppression exceeding IEEE 587 standards.
• Durable cold-rolled steel case and built-in cooling fins designed for effective heat dissipation.

Specifications

• Brand: Johnson Controls
• Model / MPN: S66AA-1C
• Line Voltage Range: 120 / 208 / 240 / 277 VAC, 60 Hz
• Input Signal: 0–10 VDC analog input signal (1–10 VDC operational range)
• Low Voltage Input: 20–30 VAC, Class 2
• Signal Input Impedance: 10,000 ohms
• Enclosure Type: NEMA 1 indoor-rated housing
• Mounting Orientation: Vertical only, with cooling fins clear of obstructions
• Full Load Amperes (FLA): 9.8 A at 120 VAC, 9.3 A at 208 VAC, 8.0 A at 240 VAC, 6.9 A at 277 VAC
• Locked Rotor Amperes (LRA): 24 A across line voltages

Applications

• Designed for controlling single-phase permanent split capacitor (PSC) or shaded pole condenser fan motors in commercial HVACR applications.
• Used to regulate fan speeds in commercial air handling units, fan coil units, and variable air volume (VAV) box controllers to meet exact CFM requirements.
• Seamlessly integrates with Building Automation Systems (BAS) and Direct Digital Control (DDC) controllers for centralized speed and head pressure management.