General Information
RT-SVX058B-EN
7
Unit Description
Before shipment, each unit is leak tested, dehydrated,
charged with refrigerant and compressor oil, and run
tested for proper control operation.
Direct-drive, vertical discharge condenser fans are
provided with built-in thermal overload protection.
The stages of capacity control for these units are achieved
by starting the Economizer Control Actuator (ECA).
Economizer Control Actuator
Electromechanical Control
The ECA monitors the mixed air temperature, return air
temperature, minimum position setpoint (local or
remote), power exhaust setpoint, CO
2
setpoint, CO
2
, and
ambient dry bulb/ enthalpy sensor or comparative
humidity (return air humidity against ambient humidity)
sensors, if selected, to control dampers to an accuracy of
±5 percent of stroke. The actuator is spring returned to the
closed position any time that power is lost to the unit. It is
capable of delivering up to 25 in·lb of torque and is
powered by 24 Vac.
JADE Economizer Control (For Low Leak
Economizer (LLE) Only)
The JADE controller is a standalone economizer controller
that provides outdoor air dry-bulb economizer control
standard. With optional Sylk Bus sensors, the controller
can provide comparative or reference enthalpy control.
Dampers are controlled to an accuracy of ±3.2 percent of
stroke. The actuator is spring returned to the closed
position any time that power is lost to the actuator. It is
capable of delivering up to 44 in·lb of torque and is
powered by 24 Vac.
System Input Devices &
Functions
The unit must have a thermostat input in order to operate.
The descriptions of the following basic input devices used
within the unit are to acquaint the operator with their
function as they interface with the various features.
Refer to the unit’s electrical schematic for the specific
device connections. The following controls are available
from the factory for field installation.
Drain Pan Condensate Overflow Switch
(Optional)
This input incorporates the Condensate Overflow Switch
(COF) mounted on the drain pan. When the condensate
level reaches the trip point, the COF relay energizes and
opens the 24VAC control circuit, disabling the unit. A delay
timer prevents the unit from starting for 3 minutes.
Phase Monitor
The Phase Monitor is a three-phase line monitor module
that protects against phase loss, phase reversal and phase
unbalance. It is intended to protect compressors from
reverse rotation. It has an operating input voltage range of
190–600 Vac, and LED indicators for ON and FAULT. There
are no field adjustments and the module will automatically
reset from a fault condition.
Discharge Line Thermostat Control
The high pressure controls and discharge line thermostats
are wired in series between the thermostat signal and the
compressor contactors. If the high pressure control switch
or the discharge line thermostat open, the 24VAC signal
from the thermostat is interrupted and the compressor is
disabled. There is no automatic lockout.
Power Exhaust Control (Optional)
The power exhaust fan is started whenever the position of
the economizer dampers meets or exceed the power
exhaust setpoint when the indoor fan is on.
The setpoint panel is located in the return air section and
is factory set at 25% (50% for LLE).
To configure the LLE controller, set EXH1 SET (or EXH1 L
& EXH1 H with two-speed fan) in the SETPOINTS menu. 2-
speed fan mode requires AUX2 I set as W.
Evaporator Frost Control (Optional)
This input incorporates the Frostat™ control (FOS)
mounted in the indoor coil and can be activated by closing
a field supplied contact installed in parallel with the FOS.
If this circuit is open before the compressor is started, the
compressor will not be allowed to operate. Anytime this
circuit is opened for 5 continuous seconds during
compressor operation, the compressor for that circuit is
immediately turned “Off”. The compressor will not be
allowed to restart for a minimum of 3 minutes should the
FOS close.
Sensors
High Temperature Sensor (BAYFRST003*)
This sensor connects to the Emergency Stop Input on the
LTB and provides high limit “shutdown” of the unit. The
sensor is used to detect high temperatures due to fire in
the air conditioning or ventilation ducts. The sensor is
designed to mount directly to the sheet metal duct. Each kit
contains two sensors. The return air duct sensor
(X1310004001) is set to open at 135°F.
The supply air duct sensor (X1310004002) is set to open at
240°F. The control can be reset after the temperature has
been lowered approximately 25°F below the cutout
setpoint.
