SmartFan Inversion, a fan-speed control board, combines an ac-to-dc power supply and a dc fan control/alarm. This provides the convenience and benefits of ac input power and dc output control. Speed-controlled dc fans use 40% to 60% less power at reduced speeds compared to similar ac fans. The voltage-versus-flow curve of a dc fan is also more linear, increasing the accuracy of speed control. The board's supply input range is 95 to 240 V ac. It controls 24- or 48-V dc fans up to 4 A. Variable fan speed is based on temperature or a control signal input (4 to 20 mA, 2 to 10 V dc). Price ranges from $80 to $142, depending on volume and configuration.
Control Resources Inc.