Orion System SA Controller - Manual (Page 51)

SA Controller Technical Guide
Sequence of Operations
51
Force Modes or Overrides
Warning: No equipment protection is available during the
Force Mode of operation. That means you could start a compressor
without running the Supply Fan or could create other conditions
that WILL damage the equipment. WattMaster Controls assumes
no responsibility or liability for the misuse of Overrides that cause
damage to the equipment!
The SA Controller relay and analog outputs can be user-overridden if
the Modular Service Tool or the Prism Computer Front-End Software
is used. The System Manager cannot be used for these Force Modes.
The Modes of operation for the relays are as follows:
0 = Normal Operation
1 = Forced ON
2 = Forced OFF
The Analog Outputs are Forced when you specify a value between 0.0
and 10.0 VDC. To cancel the Force Mode, you must enter a value less
than zero, such as -1.0 VDC.
When the Analog Outputs are Forced, the display on the Modular Service
Tool or Prism program can be interpreted as the actual voltage. During
normal operation, the display indicates the percentage signal applied
based on the user-defi ned voltage limits. For example, if you defi ne a
2.0 VDC to 10.0 VDC range, then 50% would be 6.0 VDC instead of
the 5.0 VDC applied when the range is 0.0 VDC to 10.0 VDC.
As previously mentioned, Force Modes can only be activated when
using either the Modular Service Tool or the Prism Computer Front-
End Software. Furthermore, the Override condition can only remain in
effect as long as one of these Operator Interface devices is connected
and communicating with the SA Controller. That means that you cannot
Force an Override condition and then walk away from the equipment
with the Override still active. The loss of communications, removal,
or shutdown of the Operator Interface will automatically terminate the
Override within 10 minutes. This protects the equipment and prevents
an Override condition from remaining active indefi nitely, resulting in
ineffi cient or dangerous operation of the equipment.
VAV Terminal Unit Controller
Compatibility
The SA Controller is designed to communicate with Orion VAV/Zone
Controllers. The SA Controller can be confi gured to broadcast its
Internal Schedule, Time, and Date, Fan and Heat Status, and Supply
Air Temperature. The SA Controller can also broadcast Force to Max
or Force to Fixed Position during Morning Warm-up. The Orion VAV/
Zone Controllers broadcast Push-Button Overrides from Unoccupied to
Occupied. The controllers can also generate Unoccupied Heating and
Cooling calls to the SA Controller based on Setbacks.
If you are using another manufacturer’s VAV Terminal Unit Control-
lers, the SA Controller can activate a relay to inform the VAV/Zone
Controllers that the SA Controller is operating in Warm-up Mode. No
other information can be passed between the SA Controller and the other
manufacturer’s VAV Terminal Unit Controllers. This means that Over-
rides or Unoccupied Heating and Cooling calls cannot activate the SA
Controller. If you need any of these capabilities, you must use only Orion
VAV/Zone Controllers for controlling all of your VAV Terminal Units.
VAV/Zone System
When the SA Controller goes into the Occupied Mode, it initiates Morn-
ing Warm-up if the Entering Air Temperature is below the Morning
Warm-up Target Temperature Setpoint. During Morning Warm-Up, the
VAV/Zone Controllers will modulate open if the Space Temperatures
are too cold. They can also move to their Maximum Airfl ow or Fixed
Airfl ow Position Setpoint if they receive this broadcast from the SA
Controller. Once Morning Warm-up has been satisfi ed, the SA Controller
enters the Cooling Mode and the VAV/Zone Controllers will modulate
to satisfy their Space Temperature Setpoints. If the Space Temperature
falls below the Heating Setpoint, staged or modulating Reheat can be
activated to warm the space.
Communications between the SA Controller and the VAV/Zone Control-
lers are handled by the MiniLink Polling Device. Alarm Polling and
Tenant Overrides are also monitored by the MiniLink Polling Device.
Tenant Overrides are overrides generated by the Space Temperature Sen-
sor’s push button. The MiniLink Polling Device records the start and stop
times and total run times of the overrides on a daily and monthly basis.
A computer running Prism Computer Front-End Software is required to
retrieve all data acquired by the MiniLink Polling Device.
Zoning System
The SA Controller automatically confi gures itself for Voting Control
when the MiniLink Polling Device is installed and is confi gured as a
Voting System. The SA Controller sets the HVAC Mode Enable to the
Entering Air Temperature Sensor as soon as communication is acquired
with the MiniLink Polling Device. If the VAV/Zone controllers are con-
fi gured for Voting, the MiniLink Polling Device totals the Heating and
Cooling demands and determines which HVAC Mode the SA Controller
should be in. The MiniLink Polling Device broadcasts a forced Heating,
Cooling, or Vent Mode of operation to the SA Controller. Once the SA
Controller receives the broadcast to set the HVAC Mode, it operates as
previously described in the SA Controller Sequence of Operations. If
communications are lost, the SA Controller returns to its own control and
will maintain the HVAC Mode Enable Setpoints by using the Entering
Air Temperature Sensor as the Controlling Sensor.
VAV Applications