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to the compressor. Typical oil temperature during normal
operation will be approximately 130 - 150°F.
For the first 2 minutes of operation, the oil temperature
safety is bypassed. After 2 minutes of operation, if the
oil temperature is above 225°F for more than 3 seconds,
the compressor will shut down.
An example of the High Oil Temp fault message is shown
below:
S Y S
1
H I G H
S Y S
2
H I G H
AUTOMATIC RESET SAFETIES
An Automatic Reset Safety will shut the entire chiller
down on a fault when the safety threshold is exceeded
and allows automatic restart after the condition causing
the shutdown clears. Restart will occur only after anti-
recycle timers are satisfied and demand requires.
A reset hysteresis is built in to each safety so repetitive
faulting and clearing will not occur in a short time period.
An example would be if ambient temperature dropped
below the cut-out, temperature would have to rise 5°F
above the cut-out before the fault lockout would clear
and restart can occur.
When the chiller is shut down on one of these safeties, a
message will appear on the STATUS display informing
the operator of the problem. This is accessible by press-
ing the STATUS key.
Details concerning each of the three Automatic Reset
Safeties follow.
Low Water Temperature Safety
The Low Water Temperature Safety assures that the
evaporator is not damaged from freezing due to improp-
erly set control points. Whenever the chilled liquid tem-
perature drops below the programmable cut-out, the chiller
will shut down. The chiller will be re-enabled and the fault
will clear when temperature rises 4°F above the cut-out
point.
The Low Water Temperature Safety Cut-out is program-
mable by the user (Page 91). An example of the Low
Water Temperature Fault display message is shown be-
low:
C H I L L E R
L O W
W A T E R
110
O I L
T E M P
O I L
T E M P
F A U L T :
T E M P
Low Ambient Temperature Safety
The Low Ambient Temperature Safety assures that the
chiller does not run in low ambients where potential dam-
age could result due to low system pressures. It can
also be used to shut down the chiller at a temperature
where continued running of the chiller is not economical
as compared to the use of free cooling.
The Low Ambient Cut-out is programmable by the user
(Page 89). If the outdoor ambient temperature drops 1°F
below the cut-out, the chiller will shut down. The fault will
clear when the temperature rises 1°F above the cut-out.
An example of the Low Ambient Temperature Fault dis-
play message is shown below:
C H I L L E R
L O W
A M B I E N T
High Ambient Temperature Safety
The High Ambient Temperature Safety assures that the
chiller does not run in ambients above 130°F where po-
tential malfunction of system mechanical and electrical
components may result.
The High Ambient Cut-out is programmable (Page 90)
and may be adjusted for cut-outs below 130°F. The cut-
out may be programmed to cut-out at temperatures from
100 - 130°F. Whenever the ambient rises more than one
degree F above the cut-out, the chiller will shut down.
Restart will occur when temperature drops one degree F
below the cut-out. An example of the High Ambient Tem-
perature Fault display message is shown below:
C H I L L E R
H I G H
A M B I E N T
AC Under Voltage Safety
The Under Voltage Safety assures that the system is not
operated at voltages where malfunction of the micropro-
cessor could result in system damage. Whenever the
microprocessor senses an onboard control power supply
failure while a compressor is running, the chiller is shut
down. The microprocessor circuitry is capable of operat-
ing at voltages 10% below the nominal 115VAC supply
to the panel.
Auto-restart of the chiller will occur when power is reap-
plied after a 2 minute start-up timer elapses. This timer
assures that the motor has a minimum of 2 minutes to
cool under any circumstances, allowing much of the in-
ternal heating due to starting to be dissipated before an-
other start occurs.
F A U L T :
T E M P
F A U L T :
T E M P
YORK INTERNATIONAL
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