Carrier 23XL Specifikace stáhnout pdf (Strana 69)

If the transducer value does not move to 0 psig (0 kPa),

the transducer will return to the original reading. If the

pressure is within the allowed range, check the voltage

ratio of the transducer. To obtain the voltage ratio, divide

the voltage (dc) input from the transducer by the supply

voltage signal, measured at the PSIO terminals J7-J34 and

J7-J35. For example, the condenser transducer voltage in-

put is measured at PSIO terminals J7-1 and J7-2. The volt-

age ratio must be between 0.80 vdc and 0.11 vdc 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 240

and 260 psig (1655 and 1793 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

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 0.536 and 0.634 vdc to allow calibration. Change

the pressure at the transducer until the ratio is within the

acceptable range. Then attempt to calibrate to the new

pressure 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 a transducer.

Control Algorithms Checkout Procedure — In

the LID Service menu, one of the tables is Control Algo-

rithm Status. This table contains 4 maintenance tables which

may be viewed in order to see how the particular control

algorithm is operating. The 4 tables are:

MAINT01 Capacity

Control

This table shows all values that are used

to calculate the chilled water/brine con-

trol point.

MAINT02 Override

Status

Details of all chilled water control over-

ride values are viewed here.

MAINT03 HGBP Status The hot gas bypass control algorithm

status is viewed from this screen.

All values dealing with this control are

displayed.

MAINT04

(PSIO

Software

Version 13

and higher)

LEAD/LAG

STATUS

This table shows the condition of LEAD/

LAG operation.

OCCDEFM Time

Schedules

Status

The Local and CCN occupied sched-

ules are displayed here in a manner

that the operator can quickly deter-

mine whether the schedule is in the OC-

CUPIED mode or not.

These maintenance tables are very useful in determining

how the control temperature is calculated, slide valve posi-

tioning reaction from load changes, control point overrides,

hot gas bypass reaction, 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, slide valve assembly, and other con-

trol outputs, such as hot gas bypass. The test can help to

determine whether a switch is defective, or a pump relay is

not operating, among other troubleshooting tests. During pump-

down 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 machine, or if the vessels are

isolated. The lockout is then terminated by the operator by

using the Terminate Lockout function after the pumpdown

procedure is reversed and refrigerant is added.

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