Individual Start Inhibit Safeties - York MILLENNIUM YCAR0315 Installation Operation & Maintenance

Micro Panel
Low Ambient Temperature Cutout:
U N I T
L O W A M B I E N T
The Low Ambient Temperature Safety protects the
chiller from running in very low temperatures which
could cause damage due to low system pressures. This
feature is programmable and can also be used to shut
down the chiller at a temperature where continued run-
ning of the chiller is not economical compared to the
use of "free" cooling techniques (see also Section 9
[8.2]/ Low Ambient Temperature Cutout [page 144]).
The fault will clear when ambient temperature rises 1°C
(2°F) above the cutout.
High Ambient Temperature Cutout:
U N I T
H I G H A M B I E N T
The High Ambient Temperature Safety protects the
chiller from running in ambients above 54°C (130°F)
where potential malfunction of system mechanical and
electrical components may result. The High Ambient
Cutout is programmable and can be set for lower limit
values if required (see also Section 9 [8.2]/ High Am-
bient Temperature Cutout [page 144]). The fault will
clear when ambient temperature drops 1°C (2°F) be-
low the cutout.
Low Leaving Chilled Liquid Temperature
Cutout:
U N I T
L O W L I Q U I D
The Low Water Temperature Safety assures that the
evaporator is not damaged from freezing due to improp-
erly set control points. It also attempts to protect the
chiller from freezing, if the flow switch should fail.
Whenever the chilled liquid temperature drops below
the programmable cutout, the chiller will shut down (see
also Section 9 [8.2] / Leaving Water Temperature Cut-
out, page 145). The chiller fault will clear when tem-
perature rises 2°C (4°F) above the cutout, and cooling
demand exists.
115VAC Under Voltage Cutout:
U N I T
1 1 5 V A C U N D E R
118
F A U L T
T E M P
F A U L T
T E M P
F A U L T
T E M P
F A U L T
V O L T A G E
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 9 (8.2, page
146).
Flow Switch Open (No Run Permissive):
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 should be connected in series with the flow switch.
If the flow switch opens, all systems controlled by the
panel it is connected to will shut down and a NO RUN
PERM (Permissive) 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 INDIVIDUAL START INHIBIT SAFETIES

System start inhibits prevent a system from starting if
the inhibit value is exceeded. This prevents damage to
the compressor, which should not start under the given
conditions. Inhibits can only prevent a system from op-
erating and cannot shut a system off. Inhibits are not
logged in the History buffer.
When the chiller is shut down on one of these safeties,
a message will appear on the STATUS display inform-
ing the operator of the problem. This is accessible by
pressing the STATUS key.
FORM 150.52-NM2 (1001)
R U N P E R M
R U N P E R M
YORK INTERNATIONAL