Trane CVGF-SVU02B-E4 Operation And Maintenance Manual page 60

The shorting contactor (2K3)
has already been energized
from (F) above. The
compressor motor (4M1) starts
in the "Wye" configuration, an
auxiliary contact (2K1-AUX)
locks in the start contactor
(2K1) coil.
7.After the compressor motor
has accelerated and the
maximum phase current has
dropped below 85 percent of
the chiller nameplate RLA for
1.5 seconds, the starter
transition to the "Delta"
configuration is initiated.
8.The transition contactor (2K4)
is closed through relay 2A1-J2,
placing the transition resistors
(2R1, 2R2, and 2R3) in parallel
with the compressor motor
windings.
9.The shorting contactor (2K3) is
opened through the opening
of relay 2A1-J4 100 msec after
the closure of the transition
relay 2A1-J2.
60
Control System
Components
10. The run contactor (2K2) is
closed through relay 2A1-J6,
shorting out the transition
resistors 260 milliseconds
after the opening of the
shorting relay 2A1-J4. This
places the compressor motor
in the "Delta" configuration
and the starter module waits
to look for this transition for
2.35 seconds through the
closure of the transition
complete contacts 2K2- AUX
at module 2A1-J12 input.
11. The starter module must now
confirm closure of the
transition complete contact
(2K2- AUX) within 2.32 to
2.38 seconds after the run
relay (2A1-J6) is closed.
Finally, the transition relay
(2A1-J2) is opened de-
energizing the transition
contactor (2K4) and the
compressor motor starting
sequence is complete.
An MMR diagnostic will be
generated if the transition
complete contacts (2K2-AUX) do
not close.
Now that the compressor motor
(4M1) is running in the "Delta"
configuration, the inlet guide
vanes will modulate, opening
and closing to the chiller load
variation by operation of the
stepper vane motor actuator
(4M2) to satisfy chilled water
setpoint. The chiller continues to
run in its appropriate mode of
operation: Normal, Softload,
Limit Mode, and so forth
CVGF-SVU02B-E4