High Country Tek emc-3 - Manual (Page 10)

Page 10 of 39
emc-3 Controller Module
User Guide – Rev A
Reverse Mode Operation
A Reverse Cycle may be initialized either Manually or Automatically.
initiation of a Manual Reverse Cycle is done by momentarily toggling the
Reverse Input at any time that the Ignition Switch is “On”. A Manual Reverse
Cycle Request is considered valid if the Reverse Input pulse is between 500mS
and 3.0S in duration. Pulses of less than 500mS will be ignored. Pulses lasting
longer than 3 seconds will be considered a fault and cancel the Reverse Cycle.
This prevents a shorted switch from holding the fans in reverse.
The Auto Reverse feature will initiate a reverse cycle at a period determined by
the “Auto Reverse Interval Minutes” set point. When set to 0, the Auto Reverse
Feature is disabled. When the “Auto Reverse Interval Minutes” is set, the Auto
Reverse Cycle timer is reset each time an Auto Reverse Cycle is initiated. This
means that each Auto Reverse Cycle is run within the period for the next cycle.
Valid Auto Reverse Intervals are 2 to 500 Minutes (8 hours).
NOTE:
Momentarily toggling the Reverse Input during any active Reverse Cycle will
cancel that Reverse Cycle.
Expiration of the Auto Reverse Interval Timer or toggling the Reverse Input
anytime the System is enabled will cause a reverse cycle. During a Reverse
Cycle, the following sequence takes place;
1. The “Fans in Reverse Output begins flashing at ≈ 1 Hz
2. All the fans freewheel for the period determined by the “Reverse Dwell
Seconds” set point. (all Banks set to “Bank n Off DYCY”)
3. The Reverse signal is sent to all Fan Banks, “Bank n Reverse DYCY”
4. All Banks remain in Reverse for the period determined by the “Reverse
Cycle Seconds” Set point.
5. The “Fans in Reverse Output stops flashing
6. All fans banks resume normal operation.