Installation and Maintenance Manual

Controls
76 SCXG-SVX01H-EN
BCI-Points List
Refer to ACC-SVP*-EN
Phase Monitor
Unit is equipped with phase monitor in control box.The
phase monitor will protect against phase loss, imbalance
and reversal of line voltage. If a fault occurs, the red LED
will energize. While the fault condition is present, the
phase monitor interrupts the 115V control circuit. If no
faults are observed, a green LED will be energized.
Unit Control Components
The Modular Series IntelliPak self-contained unit is
controlled by a microelectronic control system that
consists of a network of modules.These modules are
referred to as unit control modules (UCM). In this manual,
the acronym UCM refers to the entire control system
network.
These modules perform specific unit functions using
proportional/integral control algorithms.They are
mounted in the unit control panel and are factory wired to
their respective internal components. Each module
receives and interprets information from other unit
modules, sensors, remote panels, and customer binary
contacts to satisfy the applicable request; i.e.,
economizing, mechanical cooling, heating, ventilation.
Following is a detailed description of each module’s
function.
RTM Module Board - Standard on all Units
The RTM responds to cooling, heating, and ventilation
requests by energizing the proper unit components based
on information received from other unit modules, sensors,
remote panels, and customer supplied binary inputs. It
initiates supply fan, exhaust fan, exhaust damper, variable
frequency drive output, and airside economizer operation
based on that information.
Reference the RTM points list.
Note: Emergency stop and external auto/stop, stop the
unit immediately, emergency stop generates a
manual reset diagnostic that must be reset at the
unit human interface. External auto-stop will return
the unit to the current operating mode when the
input is closed, so this input is auto reset.
RTM Remote Economizer Minimum Position
The remote minimum position potentiometer,
BAYSTAT023A, provides a variable resistance (0-270
ohms) to adjust the economizer minimum position from 0
to 100% when connected to the economizer remote
minimum position input of the RTM. The RTM must be
selected as the source for economizer minimum position.
If the RTM is the selected source for economizer minimum
position, and if a valid resistance per Table 43, p. 76 is
provided to the RTM remote minimum position input, the
OA cfm compensation function will not operate, even if
enabled. “Default” is the only possible source for
economizer minimum position when using the OA cfm
compensation function.
RTM Analog Outputs
The RTM has two 0-10 vdc outputs: one for the supply fan
and one for the economizer option.These outputs provide
a signal for one or two damper actuators.There are no
terminal strip locations associated with these wires.They
go directly from pins on RTM circuit board to actuator
motor.
RTM Binary Outputs
The RTM has an output with pressure switch proving
inputs for the supply fan. There is a 40 second delay from
when the RTM starts the supply fan until the fan proving
input must close.A fan failure diagnostic will occur after 40
seconds.This is a manual reset diagnostic, and all heating,
cooling, and economizer functions will shut down. If this
proving input is jumped, other nuisance diagnostics will
occur. If the proving input fails to close in 40 seconds, the
economizer cycles to the minimum position.This is a
manual reset diagnostic. External control of the fan is not
recommended.
VAV Drive Max Output
This is a single-pole, double-throw relay rated at a
maximum voltage of 24 vac, two amps.The relay contacts
of this relay switch when the unit goes from the occupied
mode to the unoccupied mode by means of the occupied
binary input. The contacts will stay switched during the
unoccupied and morning warmup mode.They will return
to the position shown on the unit wiring diagram when the
unit returns to the occupied mode.This binary output
signals the VAV boxes or other terminal devices to go full
open.
RTM Alarm Relay
This is a single pole, double throw relay rated at a
maximum voltage of 24 vac, two amps max. Relay
contacts can be programmed from the unit human
interface.This relay can be programmed to pick up on any
one or group of diagnostics from the unit human interface.
Table 43. Economizer remote minimum position input
resistance
Input resistance Economizer min. position
0 - 30 ohms 0 %
30 - 240 ohms 0-100 % (linear)
240 - 350 ohms 100 %
> 350 ohms N/A
(a)
(a) A resistance greater than 350 ohms is assumed to be an open
circuit. The system will use the default minimum position value.