YVAA Style A Air-Cooled Screw Liquid Chillers ... - Johnson Controls
YVAA Style A Air-Cooled Screw Liquid Chillers ... - Johnson Controls
YVAA Style A Air-Cooled Screw Liquid Chillers ... - Johnson Controls
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
SECTION 7 - OPERATION<br />
(250°F). A system will also be inhibited from starting if<br />
the discharge temperature is above 93°C (200°F). The<br />
Status display fault message for this safety is shown<br />
below:<br />
92<br />
SYS X YYYYYYYY HIGH DISCHARGE TEMP<br />
The X indicates the system and YYYYYYY indicates<br />
the system is in a “FAULT” condition and will restart<br />
when the 120 second anti-recycle timer times out or<br />
“LOCKOUT” and will not restart until the operator<br />
clears the fault using the keypad.<br />
Low Discharge Superheat Cutout Fault<br />
The Low Discharge Superheat safety helps protect the<br />
compressor from liquid floodback through the economizer<br />
line due to a high flashtank level. It also helps<br />
protect the compressor from excessive oil in circulation<br />
due to excess oil charge in the system.Excessive<br />
oil in circulation brings back liquid refrigerant which<br />
is entrained in the oil. The liquid then drops out once it<br />
enters the compressor.<br />
The safety is ignored for the first 10 minutes of operation<br />
if the system economizer feed valve is closed<br />
(0%) and for 5 minutes of operation if the economizer<br />
feed valve is open greater than 0%. If the discharge superheat<br />
falls below 2.8°C (5.0°F) for 5 minutes under<br />
either condition, the system will shut down.<br />
The X indicates the system and YYYYYYY indicates<br />
the system is in a “FAULT” condition and will restart<br />
when the 120 second anti-recycle timer times out or<br />
“LOCKOUT” and will not restart until the operator<br />
clears the fault using the keypad.<br />
Sensor Failure Cutout Fault<br />
The Sensor Failure Cutout prevents the system from<br />
running when a critical sensor (transducer, level sensor,<br />
or motor winding temp sensor) is not functioning<br />
properly and reading out of range. This safety is<br />
checked at startup and will prevent the system from<br />
running if one of the sensors has failed.<br />
The sensor failure safety will also fault and shutdown<br />
a system while in operation, if a safety threshold is exceeded<br />
or a sensor reads out of range (high or low).<br />
Following is the Status display fault message.<br />
SYS X YYYYYYYY SENSOR FAILURE:<br />
ZZZZZZZZZZZZ<br />
FORM 201.28-NM1.1<br />
ISSUE DATE: 8/29/2012<br />
The X indicates the specific system.<br />
YYYYYYYY will either indicate the system<br />
is in a “FAULT” condition and will restart<br />
when the fault clears, or “LOCKOUT”<br />
after 3 faults and will not restart until the<br />
operator clears the fault using the keypad.<br />
ZZZZZZZZZZZ indicates the failed sensor below:<br />
• SUCT PRESS<br />
• OIL PRESS<br />
• DSCH PRESS<br />
• MOTOR TEMP X *<br />
* The Unit Setup Mode allows a specific motor temperature sensor<br />
to be ignored, if it fails.<br />
The start inhibit thresholds for each sensor are shown<br />
in the following table.<br />
TABLE 8 - START INHIBIT SENSOR THRESHOLDS<br />
SENSOR<br />
SUCTION<br />
TRANSDUCER<br />
OIL<br />
TRANSDUCER<br />
DISCHARGE<br />
TRANSDUCER<br />
MOTOR TEMP.<br />
SENSOR<br />
LOW<br />
THRESHOLD<br />
HIGH<br />
THRESHOLD<br />
0.3VDC 4.7VDC<br />
0.3VDC 4.7VDC<br />
0.3VDC 4.7VDC<br />
0°C (0ºF) 116°C (240ºF)<br />
High Motor Temperature Cutout Fault<br />
The High Motor Temperature Cutout prevents a compressor<br />
from running when its motor temperature is too<br />
high. A system will fault and shut down when any compressor<br />
motor temperature sensor rises above 121°C<br />
(250°F). The system will be inhibited from starting if<br />
its motor temperatures sensors indicate temperatures<br />
above 116°C (240°F). If any single temperature sensor<br />
is being ignored under the Unit Set-up Mode, that<br />
sensor will not be utilized when evaluating motor temperature.<br />
Below is a sample Status display fault message:<br />
SYS X YYYYYYYY HIGH MOTOR TEMP<br />
JOHNSON CONTROLS