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System Input Devices &
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 se-
lected to interface with the RTRM.
The descriptions of the following basic In-
put Devices used within the RTRM net-
work are to acquaint the operator with
their function as they interface with the
various modules. Refer to the unit's elec-
trical 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 can be connected
to sense indoor fan operation:
FFS (Fan Failure Switch) If air flow
through the unit is not proven by the dif-
ferential pressure switch connected to the
RTOM (factory set point 0.07 " w.c.
(17.4 Pa)) within 40 seconds nominally,
the RTRM will shut off all mechanical op-
erations, lock the system out, send a di-
agnostic to ICS, and the SERVICE out-
put will flash. The system will remain
locked out until a reset is initiated either
manually or through ICS.
6
General Information
Clogged Filter Switch (Optional)
The unit mounted clogged filter switch
monitors the pressure differential across
the return air filters. It is mounted in the fil-
ter 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.(124.5 Pa). The contacts will auto-
matically open when the pressure differ-
ential across the filters decreases to ap-
proximately 0.4" w.c.(99.6 Pa). 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 con-
tinue to operate regardless of the status
of the filter switch.
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 compres-
sor 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.
Low Pressure Control
ReliaTel Control
When the LPC is opened for 1 continu-
ous second, the compressor for that cir-
cuit is turned off immediately. The com-
pressor 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 di-
agnostic communicated to ICS
cable, and a manual reset will be required
to restart the compressor.
High Pressure Control
ReliaTel Control
The high pressure controls are wired in
series between the compressor outputs
on the RTRM and the compressor
contactor coils. If the high pressure control
switch opens, the RTRM senses a lack
of current while calling for cooling and
locks the compressor out.
On dual circuit units, if the high pressure
control opens, the compressor on the af-
fected circuit is locked out. A manual reset
for the affected circuit is required.
Lead/Lag Control (Dual Circuit Only)
ReliaTel Control
Lead/Lag is a selectable input located on
the RTRM. The RTRM is configured from
the factory with the Lead/Lag control
disabled. To activate the Lead/Lag
function, simply cut the wire connected to
J3-8 at the RTRM. When it is activated,
each time the designated lead compres-
sor is shut off due to the load being
satisfied, the lead compressor or refrigera-
tion circuit switches. When the RTRM is
powered up, i.e. after a power failure, the
control will default to the number one circuit
compressor.
if appli-
TM
T_C-IOM-2A
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