Trim Refrigerant Charge; Scheduled Maintenance; Run Times; Inspect The Power Panel - Carrier AquaEdge 19MV Start-Up, Operation And Maintenance Instructions Manual

Trim Refrigerant Charge

If to obtain optimal chiller performance it becomes necessary to
adjust the refrigerant charge, operate the chiller at design load and
then add or remove refrigerant slowly until the difference between
the leaving chilled water temperature and the evaporator refriger-
ant temperature reaches design conditions or becomes a mini-
mum. Do not overcharge. Use evaporator sight glasses to visually
determine optimum charge. Look at evaporator approach and dis-
charge superheat compared with design. With LTD being at design
condition, stop adding charge when discharge superheat starts to
drop.
To remove any excess refrigerant, follow the procedure in "Trans-
fer the Refrigerant from Chiller to Pumpout Storage Tank" on
page 34.

SCHEDULED MAINTENANCE

Establish a regular maintenance schedule based on your actual
chiller requirements such as chiller load, run hours, and water
quality. The time intervals listed in this section are offered as
guides to service only.

Run Times

The HMI will display Compressor Starts Number, Compressor
Running Hours, and After Service Hours on the Main Menu 
Run Times screen. The After Service Hours should be reset to
zero by the service person or the operator each time major service
work is completed so that the time between service events can be
viewed and tracked. Previous values and associated dates should
be logged for future reference prior to resetting.

Inspect the Power Panel

Maintenance consists of general cleaning and tightening of con-
nections. Vacuum the control cabinets to eliminate dust build-up.
If the chiller control malfunctions, refer to the Troubleshooting
Guide section on page 41 for control checks and adjustments.
WARNING
Ensure power to the starter is isolated when cleaning and tight-
ening connections inside the starter enclosure. Failure to dis-
connect power could result in electrocution.

Changing Refrigerant Filters

Change the refrigerant main EXV strainer cartridge and motor
cooling filter drier on an annual basis or when the chiller is opened
for repairs. The filters can be isolated so they can be changed with
refrigerant remaining in the chiller. Change strainers/filters by
closing isolation valves and recover the trapped refrigerant. The
EXV filter cartridge can be replaced by opening the bolted end of
the strainer housing. Similarly the motor cooling in-line filter can
be replaced by slowly opening the flare fitting with a wrench and
back-up wrench to relieve pressure and then replacing with new
in-line filter. Follow good service practice and evacuate the dis-
turbed areas after filter/strainer replacement.

Inspect Safety Relief Devices and Piping

The relief device on this chiller protects the system against the po-
tentially dangerous effects of overpressure. To ensure against
damage to the equipment and possible injury to personnel, these
devices must be kept in peak operating condition.
As a minimum, the following maintenance is required.
1. At least once a year, disconnect the vent piping at the
valve outlet and carefully inspect the relief valves for any
evidence of internal corrosion or rust, dirt, scale, leakage,
etc. Verify that vent piping has a section leaning away
from the relief valves to avoid the valve outlet becoming a
trap for dirt, condensation etc.
2. If corrosion or foreign material is found, do not attempt to
repair or recondition. Replace the safety relief device.
3. If the chiller is installed in a corrosive atmosphere or the
relief devices are vented into a corrosive atmosphere,
inspect the safety relief devices at more frequent intervals.

Compressor Bearing Maintenance

The biggest risk to the 19MV compressor is damage incurred
from contact between the shaft and auxiliary roller bearings at
high rotational speeds. The number of high-speed drops that oc-
cur is kept in the MBC menu (MBC Drop Counter), and should
be checked regularly to detect when any new high-speed shaft
contact has occurred. If the PIC detects an increase in fast con-
tact revolutions, it will automatically conduct a clearance check
on the next unit startup. A clearance check can also be manually
initiated any time from the MBC home screen (so long as the
unit is not running). See Fig. 38. For more detailed information,
it may be necessary to access the MBC board directly. See
Fig. 39 for details regarding accessing the MBC cavity. A desic-
cant packet is mounted to the inside of the MBC cavity cover to
protect the electronic control boards from potential humidity that
may enter the cavity. If the cover is removed for maintenance the
packet should be replaced.
Maintaining a dry environment inside of the MBC cavity is
important to protect the MBC board electronics. Any time it is
necessary for the MBC cavity to be opened, replace the
desiccant pack.
If drop count is exceeded, the auxiliary bearings will need to be re-
placed immediately. When the drop counter is within 2000 revolu-
tions of its limit contact Carrier service engineering to schedule
maintenance to avoid unexpected down time. Ensure to revise the
drop count limits to keep track of bearing wear. The drop counter
monitors the number of full revolutions the motor shaft makes
while it is in contact with the auxiliary bearings. It increments
when the shaft is rotating at over 2675 rpm while de-levitated.
New auxiliary bearings are rated for 7000 revolutions.
Fig. 38 — MBCCFG - MBC Configuration Screen
38
CAUTION