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McQuay OM 751 37
Description of Operation
External Binary Inputs
The UVC is provided with three binary inputs that provide the functions described below.
Figure 24: Binary inputs
These inputs each allow a single set of dry contacts to be used as a signal to the UVC. Multiple
units can be connected to a single set of dry contacts. For wiring examples, see MicroTech II
Unit Ventilator Controller IM 747.
Note – Not all of the functions listed can be used at the same time. The UVC is provided with
configuration parameters that can be adjusted to select which function is used for these
inputs where multiple functions are indicated below.
External Binary Input 1
This input can be configured as an unoccupied (default) or dew point/humidity signal.
Unoccupied Input Signal
This input allows a single set of dry contacts to be used to signal the UVC to go into
unoccupied or occupied mode. When the contacts close, the UVC goes into unoccupied mode.
When the contacts open, the UVC goes into occupied mode. Additional variables can effect
occupancy mode and override this binary input. See “Occupancy Modes” on page 24.
External Binary Input 2
This input can only be used for remote shutdown.
Remote Shutdown Input Signal
This input allows a single set of dry contacts to be used to signal the UVC to go into shutdown
mode. When the contacts close (shutdown), the UVC goes into shutdown mode. When the
contacts open. the UVC returns to normal operation. See “Special Purpose Unit Modes” on
page 21.
External Binary Input 3
This input can be configured as a ventilation lockout (default) or exhaust interlock signal.
Ventilation Lockout Input Signal
This input allows a single set of dry contacts to be used to signal the UVC to close the OA
damper. When the contacts close (ventilation lockout signal), the UVC closes the OA damper.
When the contacts open, the UVC returns to normal OA damper operation.
Binary Inputs
3 sets of dry contacts to signal UVC
Input 1: Unoccupied (default)
Input 2: Remote shutdown
Input 3: Ventilation lockout (default)
or
Exhaust interlock system