SQ4 - Four-Step Sequencer
Electronic Technician Assistant (ETA)

  The high cost of energy today makes proportional control of HVAC systems a necessity, not a luxury. With proportional control you use only the energy needed to get the job done.
   Proportional control is easy for water valves and air dampers, but more complex and cost prohibitive for electric heat units, fans and refrigeration systems. The SQ4 module simplifies the job by sequencing multiple on-off devices based on a single analog output from the controller. Now items such as cooling towers with multiple two-speed fans, staged electric heat units and multi-compressor chillers can be controlled to provide the utmost efficiency and consistency for the load at hand – all at a reasonable price.
   Each SQ4 module provides four NO/NC output relays that trigger at four fixed voltages across the 0-5 or 0-10 control voltage range. Two SQ4 modules can be cascaded to provide eight independent output stages. When closed, each output relay provides 24 VDC at 120 mA. In addition, sequencer modules are available that provide a rotational sequence as well as contact monitoring and alarm output.

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