Power Exhaust Control; (Tracking); Lead/Lag Control; Coil Frost Protection - Trane Voyager Commercial Installation, Operation And Maintenance Manual

S S t t a a r r t t u u p p
Figure 47. Transducer voltage output vs. pressure
input for building pressure
Power Exhaust Control (Tracking)
The power exhaust dampers proportionally track or
follow the fresh air (economizer) damper position. The
offset between the fresh air and the exhaust damper(s)
is adjustable, see figures beginning with
to Power Exhaust Fan Performance" tables beginning
with Table 53, p. 83.

Lead/Lag Control

Lead/Lag is a selectable input located on the RTRM. On
2 & 3 stage standard efficiency units, the RTRM is
configured from the factory with the Lead/Lag control
disabled. To activate the Lead/Lag function, simply
remove the jumper connection J3-8 at the RTRM Lead/
Lag input. When it is activated, each time the
designated lead compressor(s) is shut off due to the
load being satisfied, the lead compressor or
refrigeration circuit switches. On the 5 stage high
efficiency units, the RTRM is configured from the
factory with the Lead/Lag control enabled. With it
active, each time the designated lead compressor is
shut off due to the load being satisfied, the controls will
switch to the next staging sequence. When the RTRM is
powered up, i.e. after a power failure, the control will
default to the number one compressor.
Table 36. Capacity steps with lead/lag enabled - std
Efficiency
Unit Size
LEAD
TC*330
LAG
LEAD
TC*360
LAG
LEAD
TC*420
LAG
LEAD
TC*480 VAV
only
LAG
62
, p. 83. Refer
Step 1 Step 2 Step 3
48% 100%
52% 100%
50% 100%
50% 100%
47% 100%
53% 100%
40% 60%
100%
60% 100%
Table 36. Capacity steps with lead/lag enabled - std
Efficiency (continued)
Unit Size
LEAD
TC*600 VAV
only
LAG
Table 37. Capacity staging sequence - high Efficiency
& 40–50 tons std eff CV
Sequence
Unit Size
1
TC*330 2
3
1
TC*360 2
3
1
TC*420 2
3
1
TC*480 2
3
1
TC*600 2
3

Coil Frost Protection

The Frostat™ control monitors the suction line
temperature to prevent the evaporator from freezing
due to low operating temperatures whenever there is a
demand for cooling. When a closed circuit has
occurred for 5 seconds minimum, the RTRM turns off
all of the cooling outputs. The Supply Fan will be held
" " O O n n " " until the Frostat has been open for 5 continuous
seconds or for 60 seconds after the last compressor
was shut " " O O f f f f " " , whichever is the longest. The
compressor shutdown is communicated to Tracer, if
applicable. There is no local diagnostic for this
condition.

Modulating Hot Gas Reheat Frost

Protection

Two control schemes will be active on units configured
for Modulating Hot Gas Reheat. The first employs the
use of the Frostat function. The second scheme takes
precedence over Frostat. Operation will be as described
below.
The second scheme is in control during active hot gas
reheat or cooling and includes the use of an Entering
Step 1 Step 2 Step 3
32% 68%
100%
68% 100%
Steps
1 2 3 4
25 37 63 75
37 63 75
37 63 75
24 38 62 76
38 62 76
38 62 76
22 39 61 78
39 61 78
39 61 78
23 39 61 77
39 61 77
39 61 77
25 38 62 75
38 62 75
38 62 75
RT-SVX34R-EN
5
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100