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
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FORM 201.28-NM1.1<br />
ISSUE DATE: 8/29/2012<br />
The X indicates the system and YYYYYYY indicates<br />
the system is in a “FAULT” condition and will restart<br />
when the fault clears or “LOCKOUT” and will not restart<br />
until the operator clears the fault using the keypad.<br />
System Control Voltage Cutout Fault<br />
The System Control Voltage Cutout alerts the operator<br />
the 115VAC Control voltage to one of the systems is<br />
missing. This could be due to a system fuse that has<br />
been removed or is blown. The affected system will<br />
fault and shut down immediately when the 115VAC<br />
supply is lost.<br />
The safety will “not” shut down a system if the UNIT<br />
switch is OFF, which electrically removes the 115VAC<br />
to “all” systems. The safety is only used to indicate a<br />
situation where a single system is missing the 115VAC.<br />
The safety will not cause a lockout and the system fault<br />
will reset when power is returned. A sample message<br />
is shown below:<br />
SYS X YYYYYYYY CONTROL VOLTAGE<br />
The X indicates the system and YYYYYYY indicates<br />
the system is in a “FAULT” condition and will restart<br />
when the fault clears or “LOCKOUT” and will not restart<br />
until the operator clears the fault using the keypad.<br />
Eductor Clog Fault<br />
To sense a loss of oil return to the compressor, an eductor<br />
clog detection safety is utilized. The safety monitors<br />
the temperature of the line between the eductor<br />
and the suction line.<br />
SECTION 7 - OPERATION<br />
The control algorithm looks at the eductor line temperature<br />
once a second. At start, a clog timer is set at 600<br />
seconds. If the eductor line temperature is less than the<br />
saturated suction temperature plus 5.5°C (10°F) each<br />
time the control circuit looks at the temperature, the<br />
clog timer is reset to 600 seconds.<br />
If the eductor line temperatures is greater than the saturated<br />
suction temperature plus 5.5°C (10°F), the clog<br />
timer is decremented one second. If the temperature<br />
remains above the saturated suction temperature plus<br />
5.5°C (10°F) for 600 seconds, the clog timer will count<br />
to “0” and the system will shut down and lock out. The<br />
status fault will indicate an eductor clog fault.<br />
EDUCTOR CLOG FAULT<br />
Whenever this fault occurs, the eductor filter should be<br />
changed.<br />
The clog timer resets to 600 seconds whenever the control<br />
algorithm sees the eductor line temperature is less<br />
than the saturated suction pressure plus 5.5°C (10°F).<br />
This prevents nuisance eductor clog faults.<br />
JOHNSON CONTROLS 93<br />
7