Trane Voyager Commercial, Инструкция по установке, эксплуатации и обслуживанию

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108 RT-SVX34R-EN
Sequence of Operation
Mechanical Cooling Sequence Of
Operation
Time delays are built into the controls to increase
reliability and performance by protecting the
compressors and maximizing unit efficiency.
Units Without an Economizer
For 27.5 to 35 Ton units, when mechanical cooling is
required, the RTRM energizes the Compressor
Contactor (CC1) coil. When the CC1 contacts close, the
Compressor CPR1 and Outdoor Fan Motor (ODM1) will
start providing the 3 minute “off” time has elapsed.
ODM2 and ODM3 cycles off/on based on the outdoor
ambient temperature as measured by the Outdoor Air
Sensor (OAS). CPR1 cycles off as required providing
the 3 minute “on” time has elapsed.
With CPR1 operating for a minimum of 3 minutes. If
additional cooling is required, the RTRM energizes the
2nd compressor contactor (CC2) to bring on CPR2.
While CPR1 continues to run, CPR2 cycles on/off as
needed to meet the cooling requirements.
For 40 Ton constant volume and variable air volume
applications, once CPR1 has operated for a minimum
of 3 minutes, and additional cooling is required, the
RTRM cycles CPR1 off and energizes compressor
contactor CC2. If additional cooling is required, the
RTRM energizes compressor contactor (CC1) providing
CPR1 has been off for a minimum of 3 minutes. This
configuration will allow the dual circuit unit to operate
with three steps of cooling if CPR1 is the lead
compressor.
For 50 Ton constant volume and variable air volume
applications, once CPR1 has operated for a minimum
of 3 minutes, and additional cooling is required, the
RTRM cycles CPR1 off and energizes compressor
contactors CC2 and CC3 simultaneously. If additional
cooling is required, the RTRM energizes compressor
contactor (CC1) providing CPR1 has been off for a
minimum of 3 minutes. This configuration allow the
dual circuit unit to operate with three steps of cooling if
CPR1 is the lead compressor.
If the indoor Fan selection switch is set to the “AUTO”
position on constant volume applications, the RTRM
energizes the Indoor Fan Contactor (F) coil
approximately one second after energizing first stage
compressor contactor (CC1). When the cooling cycle is
complete and CC1 is de-energized, the RTRM keeps the
Fan on for approximately 60 seconds to enhance unit
efficiency. On variable air volume applications, the Fan
operates continuously.
Economizer Operation Based on Dry
Bulb
Standard economizer dry bulb change over has five
field selectable temperatures 55, 63, 67, 70, 73°F. Refer
to
Table 34, p. 59 for the proper potentiometer setting
for each temperature selection.
The economizer option allows cooling utilizing outdoor
air when the temperature is below the specified dry
bulb setpoint (73° ±2°F factory setting). The air is drawn
into the unit through modulating dampers. The ECA
modulates the economizer dampers from minimum
position to full open based on a 1.5°F control point
below either the space temperature setpoint for
constant volume applications or 1.5°F around the
supply air temperature setpoint for variable air volume
applications.
If the Mixed Supply Air Sensor (MAS) senses that
supply air temperature is too cold, the dampers are
held in their current position until the supply air
temperature rises, or begin to modulate toward the
minimum position if the supply air temperature
continues to drop.
The economizer control allows fully integrated cooling
operation between the compressor(s) and the
economizer when needed to satisfy the cooling
setpoint. The RTRM will not allow a compressor to
operate until the economizer dampers have been fully
open for at least three minutes. The RTRM evaluates
the rate of temperature change during this delay and
will energize compressor(s) as needed to maintain
temperatures within setpoint deadbands.
If a power exhaust option is installed:
• The power exhaust fan(s) comes on based on the
position of the of the exhaust fan setpoint
potentiometer on the RTOM (ReliaTel Options
Module). The setpoint is factory set at 25%. The
exhaust fan(s) will come on anytime the
economizer damper position is equal to or greater
than the exhaust fan setpoint.
• The exhaust dampers have provisions to limit the
amount of exhaust airflow by limiting the
maximum opening of the damper blades.
Barometric dampers have physical damper blade
stops. These stops (sliding brackets secured with
wing-nuts) are present under the rain hood on the
non-modulating power exhaust option. There is
one stop on each side of each damper. The practical
range of blade position control is between 1.5" and
4.0" blade opening. The damper is wide-open at
4.0". The stops on each side of a damper must be in
the same position, such that the damper blade
connecting member contacts the stops at the same
time.