21
will be lit. An alarm with an ID of "dhs_alarm" will be
generated.
FIRE/SHUTDOWN INPUT (FSD) — This is a normally
closed input, which when opened, all control outputs are im-
mediately turned off, including the fan, the alarm output will
close and the red alarm lamp will be lit. An alarm with an ID of
"fire_alarm" will be generated.
CONDENSER WATER FLOW (CDWF) — This is an op-
tional switch that can be used with the Omnizone™ controller.
A thermal dispersion flow switch detects water flowing past
the sensor element and closes normally open contacts that ener-
gize a relay with normally open contacts to the unit controller.
A configuration set point is used to indicate if this switch is in-
stalled and disable alarms from the flow switch. When the flow
switch is installed, the controller will check for water flow
when flow is requested for unit operation and if flow is not de-
tected, compressor operation will be disabled. The controller
will also test or to see if there is water flow when the unit is not
operating. If there is no flow when the unit is operating or if
there is flow when the unit is not operating, the alarm output
will close and the red alarm lamp will be lit. An alarm with an
ID of "cdwf_alrm" will be generated.
DIRTY FILTERS SWITCH INPUT (DFS) — This optional
air pressure switch may be factory-installed in the 50XJ unit to
detect the pressure differential pressure across the return air fil-
ters. This switch is normally open, with manually adjustable
setting at the switch between 0.5 and 1.5 in. wg. Upon closure,
controller should wait to assure closure for minimum 1 minute,
and then the alarm output will close and the red alarm lamp
will be lit. An alarm with an ID of "flts_alarm" will be generat-
ed. However, all other unit operation should remain normal.
PHASE LOSS/REVERSAL INPUT (PRM) — A power
monitor may be installed in the unit to detect over-voltage, un-
der-voltage conditions, phase loss and/or phase reversal. Upon
switch closure a pilot relay is engaged and the input to the con-
troller is closed. In adverse power conditions, all controller out-
puts will be forced off, the alarm output will close and the red
alarm lamp will be lit. An alarm with an ID of "prm_alarm"
will be generated.
ECONOMIZER COIL FREEZE PROTECTION — This in-
put can be either a dry contact input or an averaging thermistor
sensor. This protection is installed in the 50XJ unit when the
economizer coil is provided. In the event the freeze protection
switch contacts open or the sensed economizer temperature
falls below 37 F, or the sensed economizer temperature sensor
fails, the ventilation request output will be closed, the pump
output will be closed, the compressor outputs will be opened,
the alarm output will close, the water economizer valve will
open to 100%, and the red alarm lamp will be lit. This will
maintain condenser water flow through the coil to prevent
freezing the coil while stopping all other operations that could
have contributed or will be affected by the freeze condition. An
alarm with an ID of "eco_freeze" will be generated.
If the freeze condition is maintained for 15 minutes, the sup-
ply fan will be stopped. The optional factory-installed switch is
a manually reset device. The optional factory-installed thermis-
tor will automatically reset when the return-air temperature ex-
ceeds 42 F.
COMPRESSOR
STATUS
—
Compressor status is deter-
mined from the compressor relay (CRx) inputs to the control-
ler. If a compressor input is off for several seconds while that
compressor is commanded on, the compressor output will be
shut down. After five minutes, the controller will attempt to re-
start the compressor, provided there is a call for cooling. If the
compressor fails again, the controller will shut down the com-
pressor and attempt to restart it 10 minutes later. If the com-
pressor fails again, the controller will shut down the compres-
sor and attempt to restart it 15 minutes later, assuming there is
still a call for cooling. On a third failed attempt to run the
compressor, the compressor will be locked out pending a pow-
er reset or the end of the cooling cycle (no cooling demand).
When a compressor is locked out or the controller detects
compressor operation with no call for that compressor, the
alarm output will close and the red alarm lamp will be lit. An
alarm with an ID of "dx#_alarm" will be generated, where "#"
designates which compressor (numbers 1 through 4) is locked
out. This alarm is only maintained while the controller is call-
ing for a compressor and compressor operation is not detected
or while compressor operation is detected and the controller is
not calling for operation.
An alarm with ID of "dx#_lockout" is generated when it be-
comes locked out after three run attempts.
SUPPLY FAN STATUS — Supply fan status is determined
by duct static pressure sensor. If the fan is operating and a fan
speed signal is sent to the VFD, the duct static pressure must
become greater than the supply fan proof level (minsps_sp) for
the supply fan status software point to turn on. When the duct
static pressure becomes lower than the supply fan status low set
point, the supply fan status will indicate OFF.
SUPPLY FAN FAILURE (OFF) — If the supply fan status is
off for 4 minutes while the fan output is on, the alarm output
will close and the red alarm lamp will light. An alarm with an
ID of "sf_fail" is generated. This alarm does not directly affect
unit operation; however, the cooling, heating and other outputs
require the fan status to be on before they can be engaged.
SUPPLY FAN FAILURE (ON) — If the supply fan status is
on for 4 minutes while the fan output is off, the alarm output
will close and the red alarm lamp will be lit. An alarm with an
ID of "sfs_alarm" will be generated. This error does not affect
unit operation.
REFRIGERANT PRESSURE TRANSDUCER (PRES) —
If the optional head pressure control option is enabled and the
pressure transducer input exceeds 420 psig or falls below
-6.7 psig, head pressure control will be disabled, the alarm out-
put will close and the red alarm lamp will be lit. An alarm with
an ID of "ref_pres_alarm" will be generated.
INDOOR AIR QUALITY SENSOR ALARM (IAQ) — If
an indoor air quality sensor is field-installed and configured,
the controller will consider the IAQ input invalid if the level
falls below 0 ppm or exceeds 2000 ppm, then the alarm output
will close and the red alarm lamp will be lit. An alarm with an
ID of "iaq_sns_alarm" will be generated and the control point
will show 0 ppm. This error disables demand ventilation, but
has no other effect on unit operation.
INDOOR RELATIVE HUMIDITY SENSOR ALARM
(IRH) — If an indoor relative humidity sensor is field-installed
and configured, the controller will consider the IRH input in-
valid if the level falls below 0 or exceeds 100 %, then the alarm
output will close and the red alarm lamp will be lit. An alarm
with an ID of "irh_sns_alarm" will be generated and the control
point will show 0% rh. This error disables humidity control,
but has no other effect on unit operation.
SPACE STATIC PRESSURE ALARM (BLDG PRES-
SURE) — If a building pressure sensor is field-installed and
configured, the controller will consider the pressure input in-
valid if the level falls below the configured low range set point
or exceeds the low range set point plus the sensor range. In this
case the alarm output will close and the red alarm lamp will be
lit. An alarm with an ID of "spstatic" will be generated and the
control point will show 0 in. wg. This error disables space
(building) static pressure control, but has no other effect on unit
operation.
SPACE TEMPERATURE SENSOR FAILURE (SPT) — If
a space temperature sensor (SPT) is field-installed and config-
ured, the controller will consider the SPT input invalid if the in-
put temperature falls below 2 F or exceeds 180 F for a continu-
ous 10 seconds, then the alarm output will close and the red
alarm lamp will be lit. An alarm with an ID of "spt_alarm" will
