York YCAZ33BA3, Руководство пользователя, Страница: 49 / 88

FORM 150.44-NM4
49
YORK INTERNATIONAL
LOADING AND UNLOADING
LEAVING WATER TEMPERATURE CONTROL
In leaving water temperature control, loading and un-
loading will take place as needed to keep water tem-
perature in the CONTROL RANGE between the TAR-
GET and LOW LIMIT WATER TEMPERATURE. As men-
tioned earlier in this manual, the CONTROL RANGE is
the temperature range of leaving water temperature that
is acceptable to the user and has been previously pro-
grammed into memory using the CHILLED LIQUID
TEMP RANGE KEY. Usually this is a window of water
temperatures of about 2 - 3°F. The micro will cause load-
ing and unloading actions to occur as needed to keep
leaving water temperatures in the lower half of this range.
Refer to Fig. 17 to aid in understanding the loading and
unloading scheme performed by the microprocessor.
Within the lower half of the CONTROL RANGE, the
micro-processor will not call for any further loading or
unloading unless the Rate Sensitivity is exceeded. If
temperature drop exceeds 1X the Rate Sensitivity, the
micro will unload the chiller to prevent overshoot.
If leaving water temperature should fall into the tem-
perature range “BELOW THE CONTROL RANGE”
which is below the programmed Low Limit WATER
TEMPERATURE, the microprocessor will unload the
chiller in 20 sec. intervals until water temperature rises
back into the CONTROL RANGE.
If temperature is in the upper half of CONTROL RANGE
or in the RATE CONTROL RANGE, the microprocessor
will continue loading the chiller as needed in 150 sec.
intervals until temperatures pass into the lower half of the
CONTROL RANGE. If the rate of drop in water tempera-
ture exceeds 2X the programmed Rate Sensitivity, no fur-
ther loading or unloading will result since the micro sees
the temperature dropping at an excessive rate anticipat-
ing temperature will soon fall into the CONTROL RANGE.
When temperatures are in the temperature range ABOVE
THE RATE CONTROL RANGE, the micro will load the
chiller in intervals of 30-150 sec. to bring the temperature
down as quickly as possible. The micro is capable of pro-
viding 5, 7, or 10 steps of loading/unloading although 10
steps is not available with the compressors utilized. The
chiller MUST be programmed for the number of steps
which were ordered. Otherwise, improper operation and
water temperature control problems will result.
NOTE: The micro controls loading and unloading re-
sponses on a 10 step scale regardless of the
number of stages present. Therefore, loading and
unloading responses on 5 & 7 step chillers may
appear delayed (time between steps increased)
when missing steps are activated or de-activated
by the micro, 5 STEP CONTROL IS STANDARD.
Fig. 18 shows the loading and unloading sequences
for 5 and 7 steps of control.
TEMPERATURE
RISE LOAD UNLOAD
5. LEAD COMP +1 STEP, LAG COMP + 1 STEP _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ __ _ _ _ _ _ _ _ __ _ _ _ _ _ _
4. LEAD COMP +1 STEP, LAG COMP UNLOADED _ _ _ _ _ _ _ LEAD COMP +1 STEP, LAG COMP UNLOADED
3. LEAD COMP UNLOADED, LAG COMP UNLOADED _ _ _ _ _ _ _ LEAD COMP UNLOADED, LAG COMP UNLOADED
2. LEAD COMP +1 STEP, LAG COMP OFF _ _ _ _ _ _ _ LEAD COMP +1 STEP, LAG COMP OFF
1. LEAD COMP UNLOADED, LAG COMP OFF _ _ _ _ _ _ _ LEAD COMP UNLOADED LAG COMP OFF
LEAD COMP OFF, LAG COMP OFF _ _ _ _ _ _ _ LEAD COMP OFF, LAG COMP OFF
TEMPERATURE
FALL
TEMPERATURE
RISE LOAD UNLOAD
7. LEAD COMP +2 STEPS, LAG COMP +2 STEPS _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ __ _ _ _ _ _ _ _ __ _ _ _ _ _ _
6. LEAD COMP +2 STEPS, LAG COMP +1 STEP _ _ _ _ _ _ _ LEAD COMP +2 STEPS, LAG COMP +1 STEP
5. LEAD COMP +1 STEP, LAG COMP + 1 STEP _ _ _ _ _ _ _ LEAD COMP +1 STEP, LAG COMP +1 STEP
4. LEAD COMP +1 STEP, LAG COMP UNLOADED _ _ _ _ _ _ _ LEAD COMP +1 STEP, LAG COMP UNLOADED
3. LEAD COMP +2 STEPS, LAG COMP OFF _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ __ _ _ _ _ _ _ _ __ _ _ _ _ *
2. LEAD COMP +1 STEP, LAG COMP OFF _ _ _ _ _ _ _ LEAD COMP +1 STEP, LAG COMP OFF
1. LEAD COMP UNLOADED, LAG COMP OFF _ _ _ _ _ _ _ LEAD COMP UNLOADED LAG COMP OFF
LEAD COMP OFF, LAG COMP OFF _ _ _ _ _ _ _ LEAD COMP OFF, LAG COMP OFF
TEMPERATURE
FALL
5 STEP (STANDARD)
7 STEP (OPTIONAL)
FIG. 18 – LEAVING WATER CONTROL LOADING / UNLOADING
* This step is skipped on a temperature drop.
ABOVE THE RATE CONTROL RANGE
RATE CONTROL TEMP RANGE
UPPER LIMIT OF
CONTROL RANGE
CONTROL RANGE (CR) TARGET
LOW LIMIT WATER
TEMPERATURE
BELOW THE CONTROL RANGE
FIG. 17 – LEAVING WATER TEMPERATURE CONTROL