General Information
8
RT-SVX26R-EN
System Input Devices and
Functions
The RTRM must have a zone sensor or thermostat input in
order to operate the unit. The flexibility of having several
mode capabilities depends upon the type of zone sensor or
thermostat selected to interface with the RTRM.
The descriptions of the following basic Input Devices used
within the RTRM network are to acquaint the operator with
their function as they interface with the various modules.
Refer to the unit’s electrical schematic for the specific
module connections. The following controls are available
from the factory for field installation.
Supply Fan Failure Input (Optional)
The Fan Failure Switch (FFS) can be connected to sense
indoor fan operation. If air flow through the unit is not
proven by the differential pressure switch connected to the
RTOM (factory set point 0.07“ w.c.) within 40 seconds
nominally, the RTRM will shut off all mechanical
operations, lock the system out, send a diagnostic to ICS,
and the SERVICE output will flash. The system will remain
locked out until a reset is initiated either manually or
through ICS.
Drain Pan Condensate Overflow Switch
(Optional)
This input incorporates the Condensate Overflow Switch
(COF) mounted on the drain pan and the ReliaTel Options
Module (RTOM). When the condensate level reaches the
trip point for 6 continuous seconds, the RTOM will shut
down all unit function until the overflow condition has
cleared. The unit will return to normal operation after 6
continuous seconds with the COF in a non-tripped
condition. If the condensate level causes the unit to
shutdown more than 2 times in a 3 day period, the unit will
be locked-out of operation. A manual reset of the
diagnostic system through the Zone Sensor or Building
Automation System (BAS) will be required. Cycling unit
power will also clear the fault.
Clogged Filter Switch (Optional)
The unit mounted clogged filter switch monitors the
pressure differential across the return air filters. It is
mounted in the filter section and is connected to the
RTOM. A diagnostic SERVICE signal is sent to the remote
panel if the pressure differential across the filters is at least
0.5” w.c.
The contacts will automatically open when the pressure
differential across the filters decreases to approximately
0.4” w.c.
The clogged filter output is energized when the supply fan
is operating and the clogged filter switch has been closed
for at least 2 minutes. The system will continue to operate
regardless of the status of the filter switch.
Please note that on units equipped with factory installed
MERV 13 filters, a clogged filter switch with different
pressure settings will be installed. This switch will close
when the differential pressure is approximately 0.8” w.c.
and open when the differential falls to 0.7” w.c.
Compressor Disable (CPR1/2)
This input incorporates the low pressure control (LPC) of
each refrigeration circuit and can be activated by opening
a field supplied contact installed on the LTB.
If this circuit is open before the compressor is started, the
compressor will not be allowed to operate. Anytime this
circuit is opened for 1 continuous second 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
contacts close.
If four consecutive open conditions occur during the first
three minutes of operation, the compressor for that circuit
will be locked out, a diagnostic communicated to the
remote panel (if installed), and a manual reset will be
required to restart the compressor.
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.
Low Pressure Control ReliaTel Control
When the LPC is opened for 1 continuous second, the
compressor for that circuit is turned off immediately. The
compressor will not be allowed to restart for a minimum
of 3 minutes.
If four consecutive open conditions occur during the first
three minutes of operation, the compressor will be locked
out, a diagnostic communicated to ICS™ if applicable, and
a manual reset will be required to restart the compressor.
Discharge Line Thermostat ReliaTel
Control
The high pressure controls and discharge line thermostats
are wired in series between the compressor outputs on the
RTRM and the compressor contactor coils. If the high
pressure control switch or discharge line thermostat open,
the RTRM senses a lack of current while calling for cooling
and locks the compressor out. This is an auto reset lockout.
If the circuit is open three consecutive times when the
contactor coil should be on, the RTRM sets a manual
lockout for that compressor.
