66 RT-SVX34C-EN
Startup
Phase Monitor
The Phase Monitor is a 3 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
This input incorporates the low pressure cutout of each refrigeration circuit and can be activated
by opening a field supplied contact.
If this circuit is open before a compressor(s) is started, neither compressor in that circuit will be
allowed to operate.
Anytime this circuit is opened for 5 continuous seconds, the compressor(s) in that circuit are turned
off immediately. The compressor(s) 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(s) in that circuit will be locked out, a diagnostic communicated to Tracer, and a manual
reset will be required to restart the compressor(s).
The dehumidification option has one reheat low pressure cutout (RLP). The RLP is located on the
reheat circuit.
Dehumidification Low Pressure Control
The RLP has been added to insure proper refrigerant management during active modulating hot
gas reheat operation.
The RLP will be ignored for the first 10 minutes of compressor run time during active hot gas reheat
operation. Anytime this circuit is opened for 5 continuous seconds, the compressor(s) in that circuit
are turned off immediately. The compressor(s) will not be allowed to restart for a minimum of 3
minutes. If four consecutive open conditions occur during active dehumidification, the
compressor(s) in that circuit will be locked out.
High Pressure Cutout and Temperature Discharge Limit
The high pressure controls and temperature discharge limit are wired in series between the
compressor outputs on the RTRM and the compressor contactors. On 27.5, 30, and 35 Ton units,
if the high pressure safety switch or temperature discharge limit opens, the RTRM senses a lack of
current while calling for cooling and locks both compressors out with an auto reset. On 40 and 50
Ton units, if the high pressure safety or temperature discharge limit opens, the compressor(s) on
the affected circuit is locked out. If the compressor output circuit is opened four consecutive times
during compressor operation, the RTRM will generate a manual reset lockout.
Power Exhaust Control (Standard)
The power exhaust fan is started whenever the position of the economizer dampers meets or
exceed the power exhaust setpoint when the supply fan is on.
The setpoint potentiometer is on the RTOM and is factory set at 25%.
Space Pressure Control--Statitrac
A pressure transducer is used to measure and report direct space (building) static pressure. The
user-defined control parameters used in this control scheme are Space Pressure Setpoint and
Space Pressure Deadband. As the Economizer opens, the building pressure rises and enables the
Exhaust Fan. The Exhaust dampers will be modulated to maintain Space Pressure within the Space
Pressure Deadband.
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