Trane CVGF-SVU02B-E4 Operation And Maintenance Manual page 59

CH530 and Wye-Delta
Starter Control Circuits
(Sequence of Operation)
Logic Circuits within the various
modules will determine the
starting, running, and stopping
operation of the chiller. When
operation of the chiller is
required the chiller mode is set
at ''Auto." Using customer-
supplied power, the chilled water
pump relay (5K1) is energized by
the 1A5 Module output at 1A5-
J2-4, and chilled water flow must
be verified within 4 minutes 15
seconds by the 1A6 module. The
main processors logic decides to
start the chiller based on the
differential to start setpoint. With
the differential to start criteria
met module 1A5 then energizes
the condenser water pump relay
(5K2) using customer-supplied
power at 1A5 J2-1.
CVGF-SVU02B-E4
Control System
Components
Based on the restart inhibit
function and the differential to
start setpoint, oil pump (4M3)
will be energized by 1A9 module
(1A9-J2-7). The oil pressure
switch must be closed for 30
continuous seconds and
condenser water flow verified
within 4 minutes 15 seconds for
the compressor start sequence
to be initiated.
When less than 5 seconds
remain before compressor start,
a starter test is conducted to
verify contactor state prior to
starting the compressor. The
following test or start sequence
is conducted for "Wye-Delta"
starters:
1. Test for transition complete
contact open (1A23X or
2A1-J12-2) –160 to 240 msec.
An MMR diagnostic will be
generated if the contact is
closed.
2. Delay time - 20 msec.
3. Close start contactor (2K1)
and check for no current - 500
msec. If currents are detected,
the MMR diagnostic ''Starter
Fault Type I'' is generated and
closes for one second.
4. Delay time - 200 msec.
(Opens 2K1).
5. Close shorting contactor,
(2K3) and check for no current
(1A23 or 2A1 J4-1) for one
second. If currents are
detected the MMR diagnostic
''Starter Fault Type II'' is
generated. (Starter Integrity
test)
6. If no diagnostics are
generated in the above tests,
the stop relay (2A1- J10) is
closed for two seconds and
the start relay (2A1-J8) is
closed to energize the start
contactor (2K1).
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