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Again, this cutout value increases with time until after 90
seconds it equals the programmed cutout value. If the
suction pressure now rises to more than 5 psi above the
programmed cutout value, the 90 second timer will be
reset. If the suction pressure does not rise to more than
5 psi above the cutout, the timer will remain at zero and if
the pressure then falls below the cutout again the sys-
tem will shut down on low pressure fault.
If the Dip Switch on the microprocessor board is set for
Water Cooling (See Section 3.7), the cutout is pro-
grammable between 44-70 PSIG for R-22 models, 19-
36 for R-134a models. In this mode settings of 44 PSIG
for R-22 and 19 PSIG for R-134a are recommended. If
the Switch is set for Brine Cooling (glycol) the cutout
is programmable between 20-70 PSIG for R-22 mod-
els, 4.5-36 PSIG for R-134a models. In this mode, the
cutout should be set to the saturated refrigerant pres-
sure equivalent to 18°F below the freezing/sludge tem-
perature of the chilled liquid. This programmable value
is password protected.
To program the Suction Pressure Cutout, key in the re-
quired setting and press the Enter key to store the value
into memory and scroll to the next display.
Incorrect Phase Rotation Cutout:
The Phase Rotation Safety prevents the compressor
from running in the wrong direction potentially causing
damage. The micro will shut the compressor down af-
ter four seconds of operation if the phasing of the in-
coming power wiring is incorrect.
Motor Current Imbalance Cutout:
The Motor Current Imbalance Safety checks that the
current balance between each of the three phases is
within an acceptable limit. This protects against motor
overheating and damage due to loss of one of the main
phases of the main supply phases, a faulty or worn con-
tactor, loose wiring or a fault in the motor winding.
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After 1 second of operation, the current of any phase
must be / 40% of the average current of the
three phases. If a phase current is outside these limits
for more than three seconds the system will be shut down.
High Oil Temperature Cutout:
This safety assures that oil temperature does not ex-
ceed a safe operating temperature due to a system prob-
lem in the oil cooling circuit which could cause damage
to the compressor. Typical oil temperature during nor-
mal operation will be approximately 130 - 150ºF.
For the first two minutes of operation, the oil tempera-
ture safety is bypassed. After two minutes of operation,
if the oil temperature is above 225ºF for more than three
seconds, the compressor will shut down.
High Compressor Motor Current Cutout:
The High Motor Current Safety shuts a system down
and locks it out after only a single occurrence of a rise
in average motor current above the cutout point. Motor
current is monitored using 3 Current Transformers
(C.T.s) per motor, one on each phase.
Average motor current is monitored after five seconds
(Across-The-Line Starters) or 20 seconds (Wye-Delta
Starters) of compressor operation. In the first two sec-
onds of monitoring, the system will be shut down if av-
erage motor current exceeds 120% FLA. After the first
2 seconds current is monitored, the system will be shut
down if average motor current exceeds 115% FLA for
more than 3 seconds.
NOTE: FLA (full load amps) is approximately 1.2 x RLA
(rated load amps). RLA is specified on the mo-
tor / chiller nameplate and is typical current de-
mand under rated operating conditions in a fully
loaded system. When a system is fully loaded
typical motor currents may be at 60 - 85% FLA
depending on operating conditions.
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Содержание Millennium YDAS 410
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