System Fault (Safety) Status Messages - York MILLENNIUM YCAS Installation Operation & Maintenance

Micropanel
115VAC Under Voltage Cut-Out:
U N I T
1 1 5 V A C U N D E R
The Under Voltage Safety assures that the system is
not operated at voltages where malfunction of the mi-
croprocessor could result in system damage. Whenever
the microprocessor senses an on-board control power
supply failure while a compressor is running, the chiller
is shut down. The microprocessor circuitry is capable
of operating at voltages 10% below the nominal 115VAC
supply to the panel. Auto-restart of the chiller occurs
after a 2 minute start-up timer has elapsed from the
time when power is re-applied, if the AUTO RESTART
ON POWER FAILURE is enabled. Otherwise the
chiller must be manually reset. See Section 8.2 (page
139).
Flow Switch Open:
S Y S # N O
S Y S # N O
Closure of the flow switch(es) is monitored to check that
flow is present in the evaporator when a compressor is
running. Any external cycling devices fitted by the cus-
tomer are connected in series with the flow switch(es).
YCAS 2-system chillers have a single flow switch wired
to the control panel. YCAS 3-system chillers have two
flow switches mounted together with one wired to each
control panel. YCAS 4-system chillers have two flow
switches, one mounted in the flow from each evaporator
and wired to the associated control panel. If the flow
switch opens, all systems controlled by the panel it is con-
nected to will shut down and a NO RUN PERM (Per-
missive) message will be displayed. Closing of the flow
switch, when flow is present, will cause the message to
disappear and auto-restart to occur.
Never bypass a flow switch. This will
cause damage to the chiller and void
any warranties.
2.6 SYSTEM FAULT (SAFETY)
STATUS MESSAGES
A System Fault will shut the affected system down
whenever a preset safety threshold is exceeded for 3
seconds. Automatic restart will occur after the first 2
shutdowns when the anti-recycle timer times out and
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F A U L T
V O L T A G E
R U N P E R M
R U N P E R M
temperature demand exists. After any combination of 3
Manual Reset Safeties in a 90 minute time period, the
affected system will shut down and lock out on the last
fault. When one or more systems are shut down on one
of these safeties, a message will appear on the Status
display informing the operator of the problem.
The High Motor Current Safety is a
unique safety which will lock out a
system after only a single fault.
To reset a locked-out system, turn the System Switch
for the affected system to the OFF position, then back
to the ON position (see Section 1.11, Fig. 28 for switch
locations).
Before returning a locked-out system
to service, a thorough investigation of
the cause of the fault should be made.
Failure to repair the cause of the fault
while manually allowing repetitive re-
starts may cause further expensive
damage to the system.
High Discharge Pressure Cutout:
S Y S # H I G H
S Y S # H I G H
The Discharge Pressure Safety prevents system pres-
sure from exceeding safe working limits. This safety is
a backup for the mechanical High Pressure Cutout in
each system. The Discharge Pressure Safety is pro-
grammable for a range of values below the system up-
per limit (see Section 8.2 / Page 136, High Discharge
Pressure Cutout for more details).
High Discharge Temperature Cutout:
S Y S # H I G H
S Y S # H I G H
This safety protects the compressor rotors from dam-
age due to overheating, expansion, and breakdown of
the oil film seal between the rotors. It also protects
against excessive oil temperature in the discharge oil
separator.
For the first 4 seconds of operation discharge tempera-
ture is ignored. After 4 seconds of operation the com-
D S C H P R E S
D S C H P R E S
D S C H T E M P
D S C H T E M P
YORK INTERNATIONAL