Control Test - Carrier 19EF Series Start Up & Operation Manual

Calibration can be checked by comparing the pressure read-
ings from the transducer against an accurate refrigeration gage.
These readings are all viewed or calibrated from the Sta-
tus01 table on the LID. The transducer can be checked and
calibrated at 2 pressure points. These calibration points are
0 psig (0 kPa) and between 225 and 275 psig (1551 and
1896 kPa). To calibrate these transducers:
1. Shut down the compressor.
2. Disconnect the transducer in question from its Schrader
fitting.
NOTE: If the cooler or condenser vessels are at 0 psig
(0 kPa) or are open to atmospheric pressure, the trans-
ducers can be calibrated for zero without removing the
transducer from the vessel.
3. Access the Status01 table, and view the particular trans-
ducer reading; it should read 0 psi (0 kPa). If the reading
is not 0 psi (0 kPa), but within ± 5 psi (35 kPa), the
value may be zeroed by pressing the SELECT softkey
while the highlight bar is located on the transducer, and
then by pressing the ENTER . The value will now go
to zero.
If the transducer value is not within the calibration range,
the transducer will return to the original reading. If the
LID pressure value is within the allowed range (noted above),
check the voltage ratio of the transducer. To obtain the
voltage ratio, divide the voltage (dc) input from the trans-
ducer by the supply voltage signal, measured at the PSIO
terminals J7-J34 and J7-J35. For example, the condenser
transducer voltage input is measured at PSIO terminals
J7-1 and J7-2. The voltage ratio must be between
0.80 vdc and 0.11 vdc for the software to allow calibra-
tion. Pressurize the transducer until the ratio is within range.
Then attempt calibration again.
4. A high pressure point can also be calibrated between 225
and 275 psig (1551 and 1896 kPa) by attaching a regu-
lated 250 psig (1724 kPa) pressure (usually from a ni-
trogen cylinder). The high pressure point can be calibrated
by accessing the transducer on the Status01 table,
highlighting the transducer, pressing the SELECT soft-
key, and then increasing or decreasing the value to the
exact pressure on the refrigerant gage. Press ENTER
to finish. High altitude locations must compensate the pres-
sure so that the temperature/pressure relationship is
correct.
If the transducer reading returns to the previous value and
the pressure is within the allowed range, check the volt-
age ratio of the transducer. Refer to Step 3 above. The
voltage ratio for this high pressure calibration must be
between 0.585 and 0.634 vdc to allow calibration. Change
the pressure at the transducer until the ratio is within the
acceptable range. Then attempt calibrate to the new pres-
sure input.
The PIC will not allow calibration if the transducer is too
far out of calibration. A new transducer must be installed
and re-calibrated.
TRANSDUCER REPLACEMENT — Since the transduc-
ers are mounted on Schrader-type fittings, there is no need
to remove refrigerant from the vessel. Disconnect the trans-
ducer wiring by pulling up on the locking tab while pulling
up on the weather-tight connecting plug from the end of the
transducer. Do not pull on the transducer wires. Unscrew
the transducer from the Schrader fitting. When installing a
new transducer, do not use pipe sealer, which can plug the
sensor. Put the plug connector back on the sensor and snap
into place. Check for refrigerant leaks.
Make sure to use a backup wrench on the Schrader fit-
ting whenever removing any transducer. The Schrader
fitting can be removed when the transducer is removed.
Serious injury can result.
Control Algorithms Checkout Procedure —
the LID Service menu, one of the tables is Control Algo-
rithm Status. This table contains 6 maintenance tables which
may be viewed in order to see how the particular control
algorithm is operating. The 6 tables are:
MAINT01 Capacity
Control
MAINT02 Override
Status
MAINT03 Surge/
HGBP
Status
MAINT04 LEAD/LAG
Status
OCCDEFM Time
Schedules
Status
WSMDEFME Water
System
Manager
Status
These maintenance tables are very useful in determining
how the control temperature is calculated, guide vane posi-
tion, reaction from load changes, control point overrides, hot
gas bypass reaction, surge prevention, etc.
Control Test —
The Control Test feature can check all
of the thermistor temperature sensors, including those on the
Options modules, pressure transducers, pumps and their as-
sociated flow switches, the guide vane actuator, and other
control outputs, such as hot gas bypass. The tests can help
to determine whether a switch is defective, or a pump relay
is not operating, among other useful troubleshooting tests.
During pumpdown operations, the pumps are energized to
prevent freeze-up and the vessel pressures and temperatures
are displayed. The lockout feature will prevent start-up of
the compressor when no refrigerant is present in the ma-
chine, or if the vessels are isolated. The lockout is then ter-
minated by the operator by using the Terminate Lockout table
after the pumpdown procedure is reversed and refrigerant is
added.
LEGEND FOR TABLE 9, A - N
1CR AUX — Compressor Start Contact
CA P — Compressor Current
CDFL — Condenser Water Flow
CHIL S S — Chiller Start/Stop
CMPD — Discharge Temperature
CRP — Condenser Pressure
ERT — Evaporator Refrigerant Temperature
EVFL — Chilled Water Flow
GV TRG — Target Guide Vane Position
LID — Local Interface Device
MTRB — Bearing Temperature
MTRW — Motor Winding Temperature
OILPD — Oil Pressure
OILT — Oil Sump Temperature
PIC — Product Integrated Control
PRS TRIP — Pressure Trip Contact
PSIO — Processor Sensor Input/Output Module
RLA — Rated Load Amps
RUN AUX — Compressor Run Contact
SPR PL — Spare Protective Limit Input
SMM — Starter Management Module
STR FLT — Starter Fault
TXV — Thermostatic Expansion Valve
V P — Line Voltage: Percent
V REF — Voltage Reference
54
This table shows all values that are used to
calculate the chilled water/brine control point.
Details of all chilled water control override val-
ues are viewed here.
The surge and hot gas bypass control algo-
rithm status is viewed from this screen. All val-
ues dealing with this control are displayed.
This screen indicates LEAD/LAG
operation status.
The Local and CCN occupied schedules are
displayed here in a manner that the operator
can quickly determine whether the schedule
is in the OCCUPIED mode or not.
The water system manager is a CCN module
which can turn on the chiller and change the
chilled water control point. This screen indi-
cates the status of this system.
In