Orion System SA E-BUS Controller - Manual (Page 53)

SA E-BUS Controller Technical Guide
Sequence of Operations
53
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 E-BUS Controller relay and analog outputs can be user-over-
ridden 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 us-
ing 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 com-
municating with the SA E-BUS 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 E-BUS Controller is designed to communicate with Orion
VAV/Zone Controllers. The SA E-BUS Controller can be confi gured to
broadcast its Internal Schedule, Time, and Date, Fan and Heat Status, and
Supply Air Temperature. The SA E-BUS 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 Unoc-
cupied Heating and Cooling calls to the SA E-BUS Controller based
on Setbacks.
If you are using another manufacturer’s VAV Terminal Unit Controllers,
the SA E-BUS Controller can activate a relay to inform the VAV/Zone
Controllers that the SA E-BUS Controller is operating in Warm-up Mode.
No other information can be passed between the SA E-BUS Control-
ler and the other manufacturer’s VAV Terminal Unit Controllers. This
means that Overrides or Unoccupied Heating and Cooling calls cannot
activate the SA E-BUS 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 E-BUS Controller goes into the Occupied Mode, it initiates
Morning 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 E-
BUS Controller. Once Morning Warm-up has been satisfi ed, the SA E-
BUS 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 E-BUS Controller and the VAV/Zone
Controllers 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 E-BUS 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 E-BUS Controller sets the HVAC Mode
Enable to the Entering Air Temperature Sensor as soon as communica-
tion is acquired with the MiniLink Polling Device. If the VAV/Zone
controllers are confi gured for Voting, the MiniLink Polling Device totals
the Heating and Cooling demands and determines which HVAC Mode
the SA E-BUS Controller should be in. The MiniLink Polling Device
broadcasts a forced Heating, Cooling, or Vent Mode of operation to
the SA E-BUS Controller. Once the SA E-BUS Controller receives the
broadcast to set the HVAC Mode, it operates as previously described in
the SA E-BUS Controller Sequence of Operations. If communications
are lost, the SA E-BUS 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