York Millennium YCAS 310, Установка, эксплуатация и обслуживание

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FORM 201.10-NM3
71
YORK INTERNATIONAL
This type of oil failure will not be picked up by the High
Oil Differential Safety since no flow will cause the dif-
ferential through the oil piping to drop to zero.
The Low Oil Differential Safety is activated after 1 minute
of compressor operation when the oil pressure differen-
tial must be greater than 10 PSID. After two minutes it
must be greater than 20 PSID, after three minutes, 30
PSID, after four minutes, 40 PSID, and from five minutes
of operation and onwards, oil pressure must remain higher
than 50 PSID or the system will be shut down.
The micro computes “differential oil pressure”, for this
safety by measuring oil pressure as sensed by the oil
transducer and subtracting suction pressure as sensed
by the suction transducer (Oil – Suction = Oil PSID).
There is presently no display which allows the opera-
tor to view the oil pressure differential.
High Oil Temperature Cutout:
The safety assures oil temperature does not exceed a
safe operating temperature which could damage a com-
pressor. Typical oil temperature during normal opera-
tion will be approximately 130 - 150°F.
The High Oil Temperature Safety is activated after two
minutes of compressor operation, after which if oil tem-
perature is above 225°F (107.2°C) for more than three
seconds, the compressor will shut down.
Low Suction Pressure Cutout:
The Low Suction Pressure Cutout protects the evapo-
rator from damage due to ice build up caused by op-
eration at low refrigerant suction pressure or restricted
refrigerant flow. A number of transient timer features
prevent nuisance trips during start-up, compressor load-
ing, etc. The Low Suction Pressure Safety is program-
mable (See Section 8.2 / Low Suction Pressure Cutout
for more details).
After the compressor starting pump down cycle is com-
pleted (pump down to cutout or 30 seconds, which-
ever comes first), suction pressure is monitored as long
as the compressor runs. For the first 270 seconds of
running, suction pressure can be lower than the pro-
grammed cutout, but must be greater than:
S Y S # H I G H O I L T E M P
S Y S # H I G H O I L T E M P
S Y S # L O W S U C T I O N
S Y S # L O W S U C T I O N
This cutout value increases with time until after 270
seconds, it equals the programmed cutout value. If
suction pressure falls below the calculated cutout value
before 270 seconds, the system will be shut down.
After 270 seconds a transient timer system prevents
short term fluctuations in suction pressure from caus-
ing shutdown as follows: If suction pressure drops be-
low the cutout point, a 90 second transient timer be-
gins, during which the suction pressure must be greater
than:
Programmed
x
Run Time / 3 + 10
Cutout
100
Example: If Programmed Cutout = 44 PSIG
and Run-Time = 60 seconds
New Cutout = 44 x 60 / 3 + 10 = 13.2 PSIG
100
The transient timer cutout value also 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 system 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. If 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
required 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.
Programmed
x 100 - transient time left
Cutout
100
Example: If Programmed Cutout = 44 PSIG
and the timer has run 30 seconds:
New Cutout = 44 x
100 - 60
= 17.6 PSIG
100
S Y S # P H A S E R O T A T I O N
S Y S # P H A S E R O T A T I O N