Carrier 19XRV Specifications download pdf (Page 117)

117

NOTE: If the cooler or condenser vessels are at

0 psig (0 kPa) or are open to atmospheric pressure, the

transducers can be calibrated for zero without remov-

ing the transducer from the vessel.

3. Access the HEAT_EX screen and view the particular

transducer reading (the EVAPORATOR PRESSURE or

CONDENSER PRESSURE parameter on the HEAT_EX

screen). To calibrate oil pressure or liquidside flow

device, view the particular reading (CHILLED WATER

DELTA P and CONDENSER WATER DELTA P on the

HEAT_EX screen, and OIL PUMP DELTA P on the

COMPRESS screen). 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 set to zero by pressing the

softkey while the appropriate transducer parameter is

highlighted on the ICVC screen. Then press the

softkey. The value will now go to zero. No high end

calibration is necessary for OIL PRESSURE DELTA P or

flow devices.

If the transducer value is not within the calibration

range, the transducer returns to the original reading. If

the pressure 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

transducer by the TRANSDUCER VOLTAGE REF

supply voltage signal (displayed in CONTROL TEST

menu in the PRESSURE TRANSDUCERS screen) or

measure across the positive (+ red) and negative

(– black) leads of the transducer. For example, the

condenser transducer voltage reference is measured

at CCM terminals J2-4 and J2-6, the condenser trans-

ducer voltage input. The input to reference voltage

ratio must be between 0.80 and 0.11 for the software to

allow calibration. Pressurize the transducer until the

ratio is within range. Then attempt calibration again.

4. A high pressure point can also be calibrated between 25

and 250 psig (172.4 and 1723.7 kPa) by attaching a regu-

lated 250 psig (1724 kPa) pressure (usually from a

nitrogen cylinder). The high pressure point can be

calibrated by accessing the appropriate transducer param-

eter on the HEAT_EX screen, highlighting the parameter,

pressing the softkey, and then using the

or softkeys to adjust the

value to the exact pressure on the refrigerant gage. Press

the softkey to finish the calibration. Pressures at

high altitude locations must be compensated for, so the

chiller temperature/pressure relationship is correct.

The PIC II does not allow calibration if the transducer is too

far out of calibration. In this case, a new transducer must be in-

stalled and re-calibrated. If calibration problems are encoun-

tered on the OIL PRESSURE DELTA P channel, sometimes

swapping the compressor oil discharge pressure transducer and

the oil sump pressure transducer will offset an adverse trans-

ducer tolerance stack up and allow the calibration to proceed.

Control Algorithms Checkout Procedure — One

of the tables on the ICVC SERVICE menu is CONTROL AL-

GORITHM STATUS. The maintenance screens may be

viewed from the CONTROL ALGORITHM STATUS table to

see how a particular control algorithm is operating.

These maintenance screens are very useful in helping to de-

termine how the control temperature is calculated and guide

vane positioned and for observing the reactions from load

changes, control point overrides, hot gas bypass, surge preven-

tion, etc. The tables are:

Control Test — The Control Test feature can check all the

thermistor temperature sensors, pressure transducers, pumps

and their associated flow devices, the guide vane actuator, and

other control outputs such as tower fans, shunt trip relay, oil

heater, alarm relay, and hot gas bypass. The tests can help to

determine whether a switch is defective or a pump relay is not

operating, as well as other useful troubleshooting issues. Dur-

ing pumpdown operations, the pumps are energized to prevent

freeze-up and the vessel pressures and temperatures are dis-

played. The Pumpdown/Lockout feature prevents compressor

start-up when there is no refrigerant in the chiller or if the ves-

sels are isolated. The Terminate Lockout feature ends the

Pumpdown/Lockout after the pumpdown procedure is reversed

and refrigerant is added.

Control Modules

The ICVC and CCM modules perform continuous diagnos-

tic evaluations of the hardware to determine its condition.

Proper operation of all modules is indicated by LEDs (light-

emitting diodes) located on the circuit board of the ICVC and

CCM.

There is one green and one red LED located on the CCM

and ICVC boards.

RED LED (Labeled as STAT) — If the red LED:

• blinks continuously at a 2-second interval, the module is

operating properly

SELECT

ENTER

SELECT

INCREASE

DECREASE

ENTER

CAPACITY Capacity

Control

This table shows all values used

to calculate the chilled water/brine

control point.

OVERRIDE Override

Status

Details of all chilled water control

override values.

SURG_PREV Surge/

HGBP

Status

The surge and hot gas bypass

control algorithm status is viewed

from this screen. All

values dealing with this control

are displayed.

HEAT_EX Heat

Exchanger

Points

Status

All sensor inputs and calculated

values related to the heat

Exchangers. Also some of the

surge control points are shown.

LL_MAINT LEAD/LAG

Status

Indicates LEAD/LAG operation

status.

OCCDEFCM Time

Schedules

Status

The Local and CCN occupied

schedules are displayed here to

help the operator quickly deter-

mine whether the schedule is in

the “occupied” mode or not.

WSMDEFME Water

System

Manager

Status

The water system manager is a

CCN module that can turn on the

chiller and change the chilled

water control point. This screen

indicates the status of this sys-

tem.

ISM_HIST ISM Alarm

History

Displays ISM values at last fault.

LOADSHED Loadshed

Status

Displays Loadshed (Demand

Limit) status.

CUR_ALARM Current

Alarm Status

Displays current chiller alarms.

SURGPREV Surge Pre-

vention Sta-

tus

Displays all information used or

supplied by the surge prevention

algorithm.

CAUTION

Turn controller power off before servicing controls. This

ensures safety and prevents damage to the controller.

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