9
MINUTES OFF TIME (DELY, Configuration mode under
sub-mode OPT2) — This user-configurable time period is
used by the control to determine how long unit operation is
delayed after power is applied/restored to the unit. Typically,
this time period is configured when multiple machines are
located on a single site. For example, this gives the user the
ability to prevent all the units from restarting at once after a
power failure. A value of zero for this variable does not mean
that the unit should be running.
LOADING SEQUENCE — The 30GXN,GXR,HX compres-
sor efficiency is greatest at full load. Therefore, the following
sequence list applies to capacity control.
1. The next compressor is not started until all others are
running at 100%.
2. The second unloading stage is only used during initial
capacity staging of the unit at start-up.
3. Whenever a compressor is started in a circuit, the loaders
in the circuit are deenergized for 15 seconds before the
compressor is started. The loaders are energized 90 sec-
onds after the compressor is started.
CLOSE CONTROL (CLS.C, Configuration mode under
sub-mode OPT2) — When configured for Close Control, the
control is allowed to use any loading/capacity control devices
required to maintain better leaving fluid temperature
regulation. All stages of unloading are available. See
Appendix B for an example.
LEAD/LAG DETERMINATION (LLCS, Configuration
mode under sub-mode OPT2) — This
is
a
configurable
choice and is factory set to be automatic. The value can be
changed to Circuit A or Circuit B leading, as desired. Set at
automatic, the circuit with the lowest hours is started first.
Changes to which circuit is the lead circuit and which is the lag
are made when shutting off compressors.
On 30HX206-271 and 30GXN,R204-350 units set for
staged loading, the control fully loads the lead circuit before
starting the lag circuit and unloads the lag circuit first. When
these units are set for equal loading, the control maintains
nearly equal capacities in each circuit when the chiller is load-
ing and unloading.
CAPACITY SEQUENCE DETERMINATION (LOAD,
Configuration mode, under sub-mode OPT2) — This is con-
figurable as equal circuit loading or staged circuit loading with
the default set at staged. The control determines the order in
which the steps of capacity for each circuit are changed. This
control choice does NOT have any impact on machines with
only 2 compressors.
L1
L2
L3
T1
T1
T3
3
2
1
1
2
3
4
6
5
COMPRESSOR JUNCTION BOX
JUMPER BARS
COMPRESSOR CONTACTOR
1
2
3
21
22
23
TERMINAL BLOCK
1
2
3
4
5
6
1
2
3
T1
T1
T1
T2
T2
T2
T3
T3
T3
S
2M
1M
L3
L3
L3
L2
L2
L2
L1
L1
L1
1
2
3
22
21
23
TERMINAL BLOCK
COMPRESSOR STARTER ASSEMBLY
COMPRESSOR JUNCTION BOX
21
22
23
4
6
5
Fig. 5 — Across-the-Line (XL) Compressor Wiring
Fig. 6 — Wye-Delta Compressor Wiring
